197 Sentences With "gravitational attraction"

How to use gravitational attraction in a sentence? Find typical usage patterns (collocations)/phrases/context for "gravitational attraction" and check conjugation/comparative form for "gravitational attraction". Mastering all the usages of "gravitational attraction" from sentence examples published by news publications.

It's a collapsing cloud of gas, creating stars from the gravitational attraction.
That is because of the additional gravitational attraction from the mass of the mountain.
G relates the gravitational attraction between two objects to their masses and the distance between them.
It's just that it exerts and almost gravitational attraction for you if it passes in front of you.
Stuff in the early solar system had a gravitational attraction to other stuff such that it "fell" together.
Since an object's gravitational attraction is directly related to how massive it is, this device essentially weighs nearby material.
Before the neutron stars merge, each one pulls on the other via gravitational attraction, like the moon creating tides on Earth.
Woodward says inertia results through the gravitational attraction of all the objects in the universe, whose gravitational force is related to their mass.
The cluster pointed out above is a gravitational anomaly known as the Great Attractor, and its brightness is due to its gravitational attraction.
Why it matters: Davos is a small town, where plutocrats and heads of state eddy around each other, each with their own gravitational attraction.
Normally, when two galaxies collide, the supermassive black holes at their centers start to orbit one another, moving closer and closer together in an inescapable gravitational attraction.
As for the utility of a world-eating Jimmy, it would be hard to harness any radiation he emits due to the strength of his gravitational attraction.
Or, at a fixed height, it could sense the gravitational attraction of what is below; solid bedrock would give a different reading from an oil-and-gas pocket.
Romantic love for Lisa Yuskavage is something we can deride as unrealistic, yet its sweet, naïve simplicity reminds us of a youthful ideal that still exerts its gravitational attraction.
NEOs "have been nudged by the gravitational attraction of the giant planets in our solar system into orbits that allow them to enter Earth's neighborhood," according to space scientists.
Because of the complexity of the changing gravitational attraction throughout an orbit, it was thought that stability could not be achieved and any planet would be tossed out of the system.
This law, central to both Newton's and Einstein's descriptions of the force, is that the gravitational attraction between two bodies is inversely proportional to the square of the distance between them.
She suspects there is an undiscovered particle that links gravitational attraction with nature's other forces, and is planning an experiment that uses a special satellite to try to track it down.
Some flooding is common during the so-called astronomical high tide, when Earth, the moon and the sun are aligned and the gravitational attraction among these celestial bodies generate strong tidal forces.
But maybe the gravitational attraction of big money — which has completely captured the G.O.P., and has arguably kept Democrats from moving as far left as the electorate really wants — is too great.
The sea level is, for example, slightly higher above a seamount—an ocean-floor protuberance that does not make it to the surface—because the water feels the gravitational attraction of its mass.
One plan involves using sheer force to push the asteroid in a new direction, while others call for manipulating gravitational attraction or developing high-powered lasers to send the rock in a new direction.
If we're talking pancake flat, gravity would be an immediate problem: gravitational attraction goes as G(m1*m22)/r^23, where G is the gravitational constant, m21 & m22 are two masses, and r is distance.
Dr Tyler and Dr Sabaka therefore built a computer model which tried this approach on one reasonably well-understood form of oceanic displacement, the twice-daily tidal movement caused by the gravitational attraction of the moon.
At some point, the two black holes are so close to each other, that their mutual gravitational attraction starts to deform them, which brings them even closer until the two black holes merge and become one peanut-shaped object.
Such forces would, for instance, cause the gravitational attraction between the objects in question to deviate from Newton's inverse-square law, which states that the gravitational force between two bodies is inversely proportional to the square of the distance between them.
" For one thing, New York happens to be sinking for mostly unrelated geological reasons; for another, said Horton, "gravitational attraction between water and large ice sheets" means that "what's happening thousands of kilometers away, in Antarctica will have the greatest impact along the Atlantic seaboard.
It tells us a great many facts about the mathematically describable structure of physical reality, facts that it expresses with numbers and equations (e = mc2, the inverse-square law of gravitational attraction, the periodic table and so on) and that we can use to build amazing devices.
Patryk Lykawka of Kobe University claimed that the gravitational attraction of an unseen large planetary object, perhaps the size of Earth or Mars, might be responsible.
Eddington's photograph of a solar eclipse General relativity (GR) is a theory of gravitation that was developed by Einstein between 1907 and 1915. According to general relativity, the observed gravitational attraction between masses results from the warping of space and time by those masses. General relativity has developed into an essential tool in modern astrophysics. It provides the foundation for the current understanding of black holes, regions of space where gravitational attraction is so strong that not even light can escape.
For example, this happens at the equinoxes in the case of the interaction with the Sun. This can be seen to be since the near and far points are aligned with the gravitational attraction, so there is no torque due to the difference in gravitational attraction. Although the above explanation involved the Sun, the same explanation holds true for any object moving around the Earth, along or close to the ecliptic, notably, the Moon. The combined action of the Sun and the Moon is called the lunisolar precession.
Not all deformations originate within the Earth. Gravitational attraction from the Moon or Sun can cause the Earth's surface at a given point to vary by tenths of a meter over a nearly 12-hour period (see Earth tide).
The method will function due to the spacecraft's and asteroid's mutually gravitational attraction. When the spacecraft counters the gravitational attraction towards the asteroid by the use of, for example, an ion thruster engine, the net effect is that the asteroid is accelerated, or moved, towards the spacecraft and thus slowly deflected from the orbital path that will lead it to a collision with Earth. While slow, this method has the advantage of working irrespective of an asteroid's composition. It would even be effective on a comet, loose rubble pile, or an object spinning at a high rate.
Pan is a contact binary, composed of two lobes in mutual contact, held together only by their weak gravitational attraction, and typically show a dumbbell-like shape (also see 4769 Castalia). A large number of near-Earth objects are thought to be contact binaries.
The relationship of an astronomical body's size, to its distance from another body, strongly influences the magnitude of tidal force. The tidal force acting on an astronomical body, such as the Earth, is directly proportional to the diameter of that astronomical body and inversely proportional to the cube of the distance from another body producing a gravitational attraction, such as the Moon or the Sun. Tidal action on bath tubs, swimming pools, lakes, and other small bodies of water is negligible. Figure 3: Graph showing how gravitational attraction drops off with increasing distance from a body Figure 3 is a graph showing how gravitational force declines with distance.
The measurable inertia and gravitational attraction of a body in a given frame of reference is determined by its relativistic mass, not merely its invariant mass. For example, photons have zero rest mass but contribute to the inertia (and weight in a gravitational field) of any system containing them.
Extract of page 45 Gravitational attraction is inversely proportional to the square of the distance from the source. The attraction will be stronger on the side of a body facing the source, and weaker on the side away from the source. The tidal force is proportional to the difference.
The strength of the gravitational attraction between two massive objects over the distance between them represents a negative amount of gravitational potential energy in the field which attracts them. As the distance between them approaches infinity, the gravitational attraction approaches zero from the positive side of the real number line and the gravitational potential energy approaches zero from the negative side. Therefore, as two massive objects move towards each other, the motion accelerates under gravity causing an increase in the (positive) kinetic energy of the system and an increase of the same amount in the (negative) gravitational potential energy. This is because the law of conservation of energy requires that the net energy of the system will not change.
Atmospheric tides are also produced through the gravitational effects of the Moon.. Lunar (gravitational) tides are much weaker than solar thermal tides and are generated by the motion of the Earth's oceans (caused by the Moon) and to a lesser extent the effect of the Moon's gravitational attraction on the atmosphere.
This discrepancy may be due to the gravitational attraction of Jupiter, which acts as a kind of barrier, trapping incoming comets and causing them to collide with it, just as it did with Comet Shoemaker–Levy 9 in 1994. An example of typical Oort cloud comet could be C/2018 F4.
Dwarf ellipticals may be primordial objects. Within the currently favoured cosmological Lambda-CDM model, small objects (consisting of dark matter and gas) were the first to form. Because of their mutual gravitational attraction, some of these will coalesce and merge, forming more massive objects. Further mergers lead to ever more massive objects.
In theoretical general relativity, a geon is a nonsingular electromagnetic or gravitational wave which is held together in a confined region by the gravitational attraction of its own field energy. They were first investigated theoretically in 1955 by J. A. Wheeler, who coined the term as a contraction of "gravitational electromagnetic entity".
The Dwellers respond with devastating blows on his fleet. Luseferous flees under Mercatoria pursuit. Taak returns from his journey with his memory partly erased. He is still able to piece together the secret from the remaining clues: every massive body has a region of zero net gravitational attraction at its exact centre.
A charged black hole is a black hole that possesses electric charge. Since the electromagnetic repulsion in compressing an electrically charged mass is dramatically greater than the gravitational attraction (by about 40 orders of magnitude), it is not expected that black holes with a significant electric charge will be formed in nature.
In some places on Earth, there is only one high tide per day, whereas others such as Southampton have four, though this is somewhat rare. The notional tidal bulges are carried ahead of the Earth–Moon orientation by the continents as a result of Earth's rotation. The eccentric mass of each bulge exerts a small amount of gravitational attraction on the Moon, with the bulge on the side of Earth closest to the Moon pulling in a direction slightly forward along the Moon's orbit (because Earth's rotation has carried the bulge forward). The bulge on the side furthest from the Moon has the opposite effect, but because the gravitational attraction varies inversely with the square of distance, the effect is stronger for the near-side bulge.
Stars lose much of their mass when it is ejected late in their lifetimes, and sometimes thereafter as a result of a neutron star merger, thereby increasing the abundance of elements heavier than helium in the interstellar medium. When gravitational attraction causes this matter to coalesce and collapse new stars and planets are formed.
PDF (page 32) Smaller bodies colliding with one another would not have sufficiently great impact velocity to produce the pressures and temperatures required to produce shock effects, due to their lesser gravitational attraction for one another. High instantaneous pressures, in excess of 5 GPa (1 GPa = 10,000 atmospheres), are necessary to produce shock metamorphism.
The Spiderweb Galaxy (PGC 2826829, MRC 1138-262) is an irregular galaxy with a redshift of 2.156, which is 10.6 billion light years away. It has been recently imaged by the Hubble Space Telescope. It is formed from dozens of smaller galaxies that were seen in the process of merging through mutual gravitational attraction.
The geocentric gravitational constant – the product of the mass of the Earth times the Newtonian gravitational constant – can be measured to high precision from the orbits of the Moon and of artificial satellites. The ratio of the two masses can be determined from the slight wobble in the Earth's orbit caused by the gravitational attraction of the Moon.
Helium production is expected to decline along with natural gas production in these areas. Helium, which is the second-lightest chemical element, will rise to the upper layers of Earth's atmosphere, where it can forever break free from Earth's gravitational attraction. Approximately 1,600 tons of helium are lost per year as a result of atmospheric escape mechanisms.
This polar motion should not be confused with the changing direction of the Earth's rotation axis relative to the stars with different periods, caused mostly by the torques on the Geoid due to the gravitational attraction of the Moon and Sun. They are also called nutations, except for the slowest, which is the precession of the equinoxes.
The first observation testing this prediction was made in 1919. During a solar eclipse, Arthur Eddington observed that the light from stars passing close to the Sun was bent. The effect is due to the gravitational attraction of light by the Sun. The observation confirmed that the energy carried by light indeed is equivalent to a gravitational mass.
Because the perturbing force is different in direction and magnitude on opposite sides of the orbit, it produces a change in the shape of the orbit. In astronomy, perturbation is the complex motion of a massive body subject to forces other than the gravitational attraction of a single other massive body.Bate, Mueller, White (1971): ch. 9, p. 385.
In physics, a gravitational coupling constant is a constant characterizing the gravitational attraction between a given pair of elementary particles. The electron mass is typically used, and the associated constant typically denoted . It is a dimensionless quantity, with the result that its numerical value does not vary with the choice of units of measurement, only with the choice of particle.
NGC 3597 is the product of a collision between two galaxies. It is evolving into a giant elliptical galaxy. It is widely accepted that the merging of smaller galaxies due to gravitational attraction plays a major role in shaping the growth and evolution of elliptical galaxies. Such major galactic mergers are thought to have been more common at early times.
The free-fall time is the characteristic time that would take a body to collapse under its own gravitational attraction, if no other forces existed to oppose the collapse. As such, it plays a fundamental role in setting the timescale for a wide variety of astrophysical processes—from star formation to helioseismology to supernovae—in which gravity plays a dominant role.
Current space telescopes, including NASA's Hubble Space Telescope, can accurately measure mass for some types of stars, but not all. Estimates put the range for stellar mass somewhere between 8% the mass of the Sun and in excess of 60 times the mass of the Sun. The entire study was to focus on binary star systems, stars coupled through a mutual gravitational attraction.
Here Newton used what became his famous expression Hypotheses non fingo, "I formulate no hypotheses", in response to criticisms of the first edition of the Principia. ("Fingo" is sometimes nowadays translated "feign" rather than the traditional "frame"). Newton's gravitational attraction, an invisible force able to act over vast distances, had led to criticism that he had introduced "occult agencies" into science.Edelglass et al.
Variation of tides over a day Tidal power is taken from the Earth's oceanic tides. Tidal forces are periodic variations in gravitational attraction exerted by celestial bodies. These forces create corresponding motions or currents in the world's oceans. Due to the strong attraction to the oceans, a bulge in the water level is created, causing a temporary increase in sea level.
A2142 has attracted attention because of its potential to shed light on the dynamics of mergers between galaxies. Clusters of galaxies grow through gravitational attraction of smaller groups and clusters. During a merger the kinetic energy of colliding objects heats the gas between subclusters, causing marked variations in gas temperature. These variations contain information on the stage, geometry and velocity of the merger.
The Sun's gravitational attraction on the Moon pulls it toward the plane of the ecliptic, causing a slight wobble of about 9 arcmin within a 6-month period. In 2006, the effect of this was that, although the 18.6-year maximum occurred in June, the maximum declination of the Moon was not in June but in September, as shown in the third diagram.
Each of the members of a close binary system raises tides on the other through gravitational interaction. However the bulges can be slightly misaligned with respect to the direction of gravitational attraction. Thus the force of gravity produces a torque component on the bulge, resulting in the transfer of angular momentum (tidal acceleration). This causes the system to steadily evolve, although it can approach a stable equilibrium.
The electrostatic force between two charged elementary particles is vastly greater than the corresponding gravitational force between them. The gravitational attraction among elementary particles, charged or not, can hence be ignored. Gravitation dominates for macroscopic objects because they are electrostatically neutral to a very high degree. has a simple physical interpretation: it is the square of the electron mass, measured in units of Planck mass.
In physics, gravitational acceleration is the free fall acceleration of an object in vacuum — without any drag. This is the steady gain in speed caused exclusively by the force of gravitational attraction. At given GPS coordinates on the Earth's surface and a given altitude, all bodies accelerate in vacuum at the same rate. This equality is true regardless of the masses or compositions of the bodies.
Right ascension and declination are spherical coordinates analogous to longitude and latitude, respectively. Locations of objects in space can also be represented using Cartesian coordinates in an ECI frame. The gravitational attraction of the Sun and Moon on the Earth's equatorial bulge cause the rotational axis of the Earth to precess in space similar to the action of a top. This is called precession.
Maskelyne took the opportunity to note that Schiehallion exhibited a gravitational attraction, and thus all mountains did; and that Newton's inverse square law of gravitation had been confirmed. An appreciative Royal Society presented Maskelyne with the 1775 Copley Medal; the biographer Chalmers later noting that "If any doubts yet remained with respect to the truth of the Newtonian system, they were now totally removed".
Satellite systems, like planetary systems, are the product of gravitational attraction, but are also sustained through fictitious forces. While the general consensus is that most planetary systems are formed from an accretionary disks, the formation of satellite systems is less clear. The origin of many moons are investigated on a case by case basis, and the larger systems are thought to have formed through a combination of one or more processes.
Atmospheric pressure is caused by the gravitational attraction of the planet on the atmospheric gases above the surface, and is a function of the mass of the planet, the radius of the surface, and the amount and composition of the gases and their vertical distribution in the atmosphere. It is modified by the planetary rotation and local effects such as wind velocity, density variations due to temperature and variations in composition.
Peregrine is an athletic man with a gifted intelligence but possesses no superhuman powers. He is a talented writer, and a master of savate (French kick-boxing). Peregrine wears a suit of synthetic stretch fabric that incorporates an anti-gravity generator system which emits and controls anti-gravitons, enabling him to counteract gravitational attraction. He wears glider-wings that contain small hydrazine and nitrous oxide-fueled jet turbines that afford propulsion.
In accordance with Kepler's laws of planetary motion, the closer orbit is completed more quickly. Because of the small difference it is completed in only about 30 seconds less. Each day, the inner moon is an additional 0.25° farther around Saturn than the outer moon. As the inner moon catches up to the outer moon, their mutual gravitational attraction increases the inner moon's momentum and decreases that of the outer moon.
In accordance with Kepler's laws of planetary motion, the closer orbit is completed more quickly. Because of the small difference it is completed in only about 30 seconds less. Each day, the inner moon is an additional 0.25° farther around Saturn than the outer moon. As the inner moon catches up to the outer moon, their mutual gravitational attraction increases the inner moon's momentum and decreases that of the outer moon.
However, the wider significance for planetary dynamics of this purely kinematical law was not realized until the 1660s. When conjoined with Christiaan Huygens' newly discovered law of centrifugal force, it enabled Isaac Newton, Edmund Halley, and perhaps Christopher Wren and Robert Hooke to demonstrate independently that the presumed gravitational attraction between the Sun and its planets decreased with the square of the distance between them.Westfall, Never at Rest, pp.
Rich scattering of galaxies was captured by the MPG/ESO telescope. Clusters are larger than groups, although there is no sharp dividing line between the two. When observed visually, clusters appear to be collections of galaxies held together by mutual gravitational attraction. However, their velocities are too large for them to remain gravitationally bound by their mutual attractions, implying the presence of either an additional invisible mass component, or an additional attractive force besides gravity.
Many people are concerned by this, but on the whole it amounts to little more than a temporary fad. The rogue star continues on its path, now affecting the planet Jupiter and all its moons. At this point, the studies of a mathematician are published throughout the world. He explains that the intruding star and our Sun are exerting reciprocal gravitational attraction, and as a result it is being pulled deeper into the Solar System.
HD 28185 b was discovered by detecting small periodic variations in the radial velocity of its parent star caused by the gravitational attraction of the planet. This was achieved by measuring the Doppler shift of the star's spectrum. In 2001 it was announced that HD 28185 exhibited a wobble along the line-of-sight with a period of 383 days, with an amplitude indicating a minimum mass 5.72 times that of Jupiter.
The writing was later published by the society in the 1736–37 volume of Philosophical Transactions. Initially, Clairaut disagrees with Newton's theory on the shape of the Earth. In the article, he outlines several key problems that effectively disprove Newton's calculations, and provides some solutions to the complications. The issues addressed include calculating gravitational attraction, the rotation of an ellipsoid on its axis, and the difference in density of an ellipsoid on its axes.
At the dimmest part of a Cepheid's cycle, the ionized gas in the outer layers of the star is opaque, and so is heated by the star's radiation, and due to the increased temperature, begins to expand. As it expands, it cools, and so becomes less ionized and therefore more transparent, allowing the radiation to escape. Then the expansion stops, and reverses due to the star's gravitational attraction. The process then repeats.
Adhemar's theory was further developed, first by James Croll and later by Milutin Milanković. Adhemar predicted the Antarctic ice sheet and theorised about its thickness by comparing the depths of the Arctic and circum-Antarctic oceans. Finding the Antarctic oceans deeper (the measurements he used may not have been fully representative) and attributing this to the gravitational attraction of the Antarctic ice sheet, he postulated a truly enormous ice sheet approximately 90 km thick.
Figure 1: Configuration of the Sitnikov problem The Sitnikov problem is a restricted version of the three-body problem named after Russian mathematician Kirill Alexandrovitch Sitnikov that attempts to describe the movement of three celestial bodies due to their mutual gravitational attraction. A special case of the Sitnikov problem was first discovered by the American scientist William Duncan MacMillan in 1911, but the problem as it currently stands wasn't discovered until 1961 by Sitnikov.
Non-comoving observers will see regions of the sky systematically blue-shifted or red-shifted. Thus isotropy, particularly isotropy of the cosmic microwave background radiation, defines a special local frame of reference called the comoving frame. The velocity of an observer relative to the local comoving frame is called the peculiar velocity of the observer. Most large lumps of matter, such as galaxies, are nearly comoving, so that their peculiar velocities (owing to gravitational attraction) are low.
Neutron stars form as remnants of massive stars after a supernova event. Unlike their progenitor star, neutron stars do not consist of a gaseous plasma. Rather, the intense gravitational attraction of the compact mass overcomes the electron degeneracy pressure and causes electron capture to occur within the star. The result is a compact ball of nearly pure neutron matter with sparse protons and electrons in between in a space several thousand times smaller than the progenitor star.
If the Earth were a perfect sphere, there would be no precession. This average torque is perpendicular to the direction in which the rotation axis is tilted away from the ecliptic pole, so that it does not change the axial tilt itself. The magnitude of the torque from the Sun (or the Moon) varies with the angle between the Earth's spin axis direction and that of the gravitational attraction. It approaches zero when they are perpendicular.
Radar imaging using a delay-Doppler technique at the Arecibo and Goldstone observatories rendered a rotation period of hours. Based on the radar analysis, Mithra is also a strong candidate for a contact binary, which is composed of two distinct lobes in mutual contact, held together by their weak gravitational attraction. They typically show a bifurcated, dumbbell-like shape (also see 4769 Castalia). A large number of near-Earth objects are believed to be contact-binaries.
Polar wander should not be confused with precession, which is where the axis of rotation moves, in other words the North Pole points toward a different star. There are also smaller and faster variations in the axis of rotation going under the term nutation. Precession is caused by the gravitational attraction of the Moon and Sun, and occurs all the time and at a much faster rate than polar wander. It does not result in changes of latitude.
In comparison with the much weaker gravitational force, the electromagnetic force pushing two electrons apart is 1042 times that of the gravitational attraction pulling them together. Study has shown that the origin of charge is from certain types of subatomic particles which have the property of electric charge. Electric charge gives rise to and interacts with the electromagnetic force, one of the four fundamental forces of nature. The most familiar carriers of electrical charge are the electron and proton.
The Schiehallion experiment was an 18th-century experiment to determine the mean density of the Earth. Funded by a grant from the Royal Society, it was conducted in the summer of 1774 around the Scottish mountain of Schiehallion, Perthshire. The experiment involved measuring the tiny deflection of the vertical due to the gravitational attraction of a nearby mountain. Schiehallion was considered the ideal location after a search for candidate mountains, thanks to its isolation and almost symmetrical shape.
Gravitation is the attraction between objects that have mass. Newton's law states: : The gravitational attraction force between two point masses is directly proportional to the product of their masses and inversely proportional to the square of their separation distance. The force is always attractive and acts along the line joining them. If the distribution of matter in each body is spherically symmetric, then the objects can be treated as point masses without approximation, as shown in the shell theorem.
The libration of the Moon over a single lunar month. Also visible is the slight variation in the Moon's visual size from Earth. The gravitational attraction that masses have for one another decreases inversely with the square of the distance of those masses from each other. As a result, the slightly greater attraction that the Moon has for the side of Earth closest to the Moon, as compared to the part of the Earth opposite the Moon, results in tidal forces.
Bradley became the Savilian Professor of Astronomy at Oxford from 1721–1742. His contributions he made while studying at Oxford include his observations of Stellar Aberration (a motion of celestial objects), which is when he determined the value of the speed of light as 2.95 x 108 ms−1. Other contributions Bradley made include his discovery of the annual change in declination, which was apparent due to the rocking motion of the Earth's axis through the gravitational attraction of the moon.
Many of these predictions have been confirmed by experiment or observation, while others are the subject of ongoing research. General relativity has developed into an essential tool in modern astrophysics. It provides the foundation for the current understanding of black holes, regions of space where gravitational attraction is so strong that not even light can escape. Their strong gravity is thought to be responsible for the intense radiation emitted by certain types of astronomical objects (such as active galactic nuclei or microquasars).
ULAS J0015+01 is the designation given to a star discovered on July 10, 2014 as the farthest star in bound of the gravitational attraction of the Milky Way galaxy. It is estimated to lie at 900,000 light-years from the Earth, beyond the reaches of the Magellanic Clouds. Another star, ULAS J0744+25 was a bit closer. These stars are thought to be remnants of either the Milky Way's creation, or the merging of it with another small galaxy.
About 7.5 million times weaker than the Earth's gravity, this is roughly equivalent to the gravitational attraction of a compact car from half a meter away. Similarly, the gravitational pull of the dwarf planet Pluto on a person on Earth is roughly equal to that of a marble 100 meters away. Thus, the gravitational impact of the planets is far too small to be able to cause a person to weigh noticeably less, or stay in the air noticeably longer when jumping.
Beyond Neptune lies the Kuiper belt, and finally the Oort Cloud, which may extend as far as a light-year. The planets were formed 4.6 billion years ago in the protoplanetary disk that surrounded the early Sun. Through a process that included gravitational attraction, collision, and accretion, the disk formed clumps of matter that, with time, became protoplanets. The radiation pressure of the solar wind then expelled most of the unaccreted matter, and only those planets with sufficient mass retained their gaseous atmosphere.
The experimental apparatus consisted of a torsion balance with a pair of 2-inch 1.61-pound lead spheres suspended from the arm of a torsion balance and two much larger stationary lead balls (350 pounds). Cavendish intended to measure the force of gravitational attraction between the two. He noticed that Michell's apparatus would be sensitive to temperature differences and induced air currents, so he made modifications by isolating the apparatus in a separate room with external controls and telescopes for making observations.
He discovered that many of these features could be resolved into groupings of individual stars. Herschel conceived the idea that stars were initially scattered across space, but later became clustered together as star systems because of gravitational attraction. He divided the nebulae into eight classes, with classes VI through VIII being used to classify clusters of stars. NGC 265, an open star cluster in the Small Magellanic Cloud The number of clusters known continued to increase under the efforts of astronomers.
Since Dwellers are sufficiently long-lived to colonise the galaxy at sub-light speed, the very existence of such a network was considered doubtful. The Dweller List is only a list of star systems. Portals are relatively small and can be anywhere within a system so long as it is a point of zero net gravitational attraction, such as a Lagrange point. The list is useless without a certain mathematical transform needed to give the exact location of the portals.
Cosmologists at the time expected that recession velocity would always be decelerating, due to the gravitational attraction of the matter in the universe. Three members of these two groups have subsequently been awarded Nobel Prizes for their discovery. Confirmatory evidence has been found in baryon acoustic oscillations, and in analyses of the clustering of galaxies. The accelerated expansion of the universe is thought to have begun since the universe entered its dark-energy-dominated era roughly 4 billion years ago.
Under an assumption of constant gravitational attraction, Newton's law of universal gravitation simplifies to F = mg, where m is the mass of the body and g is a constant vector with an average magnitude of 9.81 m/s2 on Earth. This resulting force is the object's weight. The acceleration due to gravity is equal to this g. An initially stationary object which is allowed to fall freely under gravity drops a distance which is proportional to the square of the elapsed time.
Gravity measurements are a reflection of the earth's gravitational attraction, its centripetal force, tidal accelerations due to the sun, moon, and planets, and other applied forces. Gravity gradiometers measure the spatial derivatives of the gravity vector. The most frequently used and intuitive component is the vertical gravity gradient, Gzz, which represents the rate of change of vertical gravity (gz) with height (z). It can be deduced by differencing the value of gravity at two points separated by a small vertical distance, l, and dividing by this distance.
The stage of life of a star that produces an electroweak star is theorized to occur after a supernova collapse. Electroweak stars are denser than quark stars, and may form when quark degeneracy pressure is no longer able to withstand gravitational attraction, but may still be withstood by electroweak burning radiation pressure. This phase of a star's life may last upwards of 10 million years. The energy output of an electroweak star is limited by the quark supply rate, which is dictated by gravitational collapse.
All bodies of a sufficiently large size have gravity. This gravity usually (but not always) exerts a force equal to the standard gravitational attraction on the surface of an Earth-sized planetary body. Gravity in the Spelljammer universe is also an exceptionally convenient force, and almost always works such that "down" orients itself in a manner most humanoids would find sensible. All bodies of any size carry with them an envelope of air whenever they leave the surface of a planet or other stellar object.
For most spacecraft, changes to orbits are caused by the oblateness of the Earth, gravitational attraction from the sun and moon, solar radiation pressure, and air drag. These are called "perturbing forces". They must be counteracted by maneuvers to keep the spacecraft in the desired orbit. For a geostationary spacecraft, correction maneuvers on the order of 40–50 m/s per year are required to counteract the gravitational forces from the sun and moon which move the orbital plane away from the equatorial plane of the Earth.
The Pleiades is one of the most famous open clusters. An open cluster is a group of up to a few thousand stars that were formed from the same giant molecular cloud and have roughly the same age. More than 1,100 open clusters have been discovered within the Milky Way Galaxy, and many more are thought to exist. They are loosely bound by mutual gravitational attraction and become disrupted by close encounters with other clusters and clouds of gas as they orbit the galactic center.
This can result in a migration to the main body of the galaxy and a loss of cluster members through internal close encounters. Open clusters generally survive for a few hundred million years, with the most massive ones surviving for a few billion years. In contrast, the more massive globular clusters of stars exert a stronger gravitational attraction on their members, and can survive for longer. Open clusters have been found only in spiral and irregular galaxies, in which active star formation is occurring.
Sean O'Neil worked as a consultant for Maxis "to assist with R&D; involving dynamic generation and rendering of a fractal-based world". He maintains a website with a demonstration of procedural planet generation and a simulation of dynamic atmospheric scattering. Wright noted that he hired a handful of demoscene programmers and artists because of their familiarity with procedural generation. An example of software they used was ParticleMan, which simulated gravitational attraction between particles in a cloud, which would be incorporated into the space phase.
In July 2008, a new five issue mini-series was released by Devil's Due, which picked up where the ongoing series left off. This series further explored the origins of Lion Voltron's creation, from 12,000 years in the past to the present day. The mini-series showed Voltron existing as a single construct created by sorcerers and scientists, resembling a knight. During its battle with the first Drule Empire, Voltron was tricked by Haggar into landing on a black comet with the gravitational attraction of a singularity.
Recording of the noise of a thermogravimetric analysis device that is poorly isolated from a mechanical point of view; the middle of the curve shows a lower noise, due to a lesser surrounding human activity at night. All real measurements are disturbed by noise. This includes electronic noise, but can also include external events that affect the measured phenomenon — wind, vibrations, gravitational attraction of the moon, variations of temperature, variations of humidity, etc., depending on what is measured and of the sensitivity of the device.
Several different gravitational perturbation algorithms are used to get fairly accurate estimates of the path of objects in the solar system. People often decide to put a satellite in a frozen orbit. The path of a satellite closely orbiting the Earth can be accurately modeled starting from the 2-body elliptical orbit around the center of the Earth, and adding small corrections due to the oblateness of the Earth, gravitational attraction of the Sun and Moon, atmospheric drag, etc. It is possible to find a frozen orbit without calculating the actual path of the satellite.
The path of a small planet, comet, or long-range spacecraft can often be accurately modeled starting from the 2-body elliptical orbit around the sun, and adding small corrections from the gravitational attraction of the larger planets in their known orbits. Some characteristics of the long-term paths of a system of particles can be calculated directly. The actual path of any particular particle does not need to be calculated as an intermediate step. Such characteristics include Lyapunov stability, Lyapunov time, various measurements from ergodic theory, etc.
The point lies on the line defined by the two large masses M1 and M2, and between them. It is the point where the gravitational attraction of M2 partially cancels that of M1. An object that orbits the Sun more closely than Earth would normally have a shorter orbital period than Earth, but that ignores the effect of Earth's own gravitational pull. If the object is directly between Earth and the Sun, then Earth's gravity counteracts some of the Sun's pull on the object, and therefore increases the orbital period of the object.
Mass is both a property of a physical body and a measure of its resistance to acceleration (a change in its state of motion) when a net force is applied. An object's mass also determines the strength of its gravitational attraction to other bodies. The basic SI unit of mass is the kilogram (kg). In physics, mass is not the same as weight, even though mass is often determined by measuring the object's weight using a spring scale, rather than balance scale comparing it directly with known masses.
Stars, planets, and moons retain their atmospheres by gravitational attraction. Atmospheres have no clearly delineated upper boundary: the density of atmospheric gas gradually decreases with distance from the object until it becomes indistinguishable from outer space. The Earth's atmospheric pressure drops to about Pa at of altitude, compared to 100,000 Pa for the International Union of Pure and Applied Chemistry (IUPAC) definition of standard pressure. Above this altitude, isotropic gas pressure rapidly becomes insignificant when compared to radiation pressure from the Sun and the dynamic pressure of the solar wind.
In quantum mechanics, explicit descriptions of the representations of SO(3) are very important for calculations, and almost all the work has been done using Euler angles. In the early history of quantum mechanics, when physicists and chemists had a sharply negative reaction towards abstract group theoretic methods (called the Gruppenpest), reliance on Euler angles was also essential for basic theoretical work. Many mobile computing devices contain accelerometers which can determine these devices' Euler angles with respect to the earth's gravitational attraction. These are used in applications such as games, bubble level simulations, and kaleidoscopes.
The distance to the Moon can be measured to an accuracy of over a 1-hour sampling period, which results in an overall uncertainty of for the average distance. However, due to its elliptical orbit with varying eccentricity, the instantaneous distance varies with monthly periodicity. Furthermore, the distance is perturbed by the gravitational effects of various astronomical bodies – most significantly the Sun and less so Jupiter. Other forces responsible for minute perturbations are: gravitational attraction to other planets in the solar system and to asteroids; tidal forces; and relativistic effects.
However, geological records of sea level changes show that the redistribution of the melted ice water is not the same everywhere in the oceans. In other words, depending upon the location, the rise in sea level at a certain site may be more than that at another site. This is due to the gravitational attraction between the mass of the melted water and the other masses, such as remaining ice sheets, glaciers, water masses and mantle rocks and the changes in centrifugal potential due to Earth's variable rotation.
Orbit modeling is the process of creating mathematical models to simulate motion of a massive body as it moves in orbit around another massive body due to gravity. Other forces such as gravitational attraction from tertiary bodies, air resistance, solar pressure, or thrust from a propulsion system are typically modeled as secondary effects. Directly modeling an orbit can push the limits of machine precision due to the need to model small perturbations to very large orbits. Because of this, perturbation methods are often used to model the orbit in order to achieve better accuracy.
In physical cosmology, peculiar velocity refers to the components of a galaxy's velocity that deviate from the Hubble flow. According to Hubble's Law, galaxies recede from us at speeds proportional to their distance from us. Galaxies are not distributed evenly throughout observable space, but are typically found in groups or clusters, where they have a significant gravitational effect on each other. Velocity dispersions of galaxies arising from this gravitational attraction are usually in the hundreds of kilometers per second, but they can rise to over 1000 km/s in rich clusters.
Local concentrations of mass known as planetesimals form, and these accelerate the accretion process by drawing in additional material by their gravitational attraction. These concentrations become ever denser until they collapse inward under gravity to form protoplanets. After a planet reaches a mass somewhat larger than Mars' mass, it begins to accumulate an extended atmosphere, greatly increasing the capture rate of the planetesimals by means of atmospheric drag. Depending on the accretion history of solids and gas, a giant planet, an ice giant, or a terrestrial planet may result.
Robert L. Forward has commented that a solar sail could be used to modify the orbit of a satellite about the Earth. In the limit, a sail could be used to "hover" a satellite above one pole of the Earth. Spacecraft fitted with solar sails could also be placed in close orbits such that they are stationary with respect to either the Sun or the Earth, a type of satellite named by Forward a "statite". This is possible because the propulsion provided by the sail offsets the gravitational attraction of the Sun.
Gravitational bending of light was predicted by Einstein's general relativity in 1916, and first observed by astronomers in 1919 during a total solar eclipse. Accurate measurements of stars seen in the dark sky near the eclipsed Sun indicated a displacement in the direction opposite to the Sun, about as much as predicted by Einstein's theory. The effect is due to the gravitational attraction of the photons when they pass near the Sun on their way to Earth. This was a direct confirmation of an entirely new phenomenon and it represented a milestone in physics.
Inhomogeneities in the early universe cause the formation of walls and bubbles, where the inside of a bubble has less matter than on average. According to general relativity, space is less curved than on the walls, and thus appears to have more volume and a higher expansion rate. In the denser regions, the expansion is slowed by a higher gravitational attraction. Therefore, the inward collapse of the denser regions looks the same as an accelerating expansion of the bubbles, leading us to conclude that the universe is undergoing an accelerated expansion.
In simple terms, the theory states that matter curves the space around it, and it moves with respect to the curvature of space, including curvature caused by other matter. On Earth, gravity gives weight to physical objects, and the Moon's gravity causes the ocean tides. The gravitational attraction of the original gaseous matter present in the Universe caused it to begin coalescing and forming stars and caused the stars to group together into galaxies, so gravity is responsible for many of the large-scale structures in the Universe.
If the crew became sick or injured during the course of their mission, they would enter the rescue vehicle through a hatched docking mechanism. With execution of a short procedure, the crew return vehicles would automatically fly the crew members safely to Earth. Once undocked, the vehicle would be deorbited using a deorbital propulsion system (DPS). The eight-thruster DPS would adjust the spacecraft's attitude and retrofire to slow the X-38 down, allowing gravitational attraction to pull it back into Earth's atmosphere. A DPS module was developed by Aerojet and delivered to Johnson Space Center in 2002 for V-201.
Derivation of the Roche limit In order to determine the Roche limit, consider a small mass u on the surface of the satellite closest to the primary. There are two forces on this mass u: the gravitational pull towards the satellite and the gravitational pull towards the primary. Assume that the satellite is in free fall around the primary and that the tidal force is the only relevant term of the gravitational attraction of the primary. This assumption is a simplification as free-fall only truly applies to the planetary center, but will suffice for this derivation.
Black holes are astrophysical objects of interest due to their immense gravitational attraction. A black hole occurs when more than a certain amount of matter and/or energy is located within a small enough space. Given a large enough mass in a small enough space, the gravitational forces become large enough that within a nearby region of space, nothing - not even light - can escape from inside that region to the wider universe. The boundary of that region is known as the event horizon because an observer outside it cannot observe, become aware of, or be affected by events within the event horizon.
Some higher-order gravitomagnetic effects can reproduce effects reminiscent of the interactions of more conventional polarized charges. For instance, if two wheels are spun on a common axis, the mutual gravitational attraction between the two wheels will be greater if they spin in opposite directions than in the same direction. This can be expressed as an attractive or repulsive gravitomagnetic component. Gravitomagnetic arguments also predict that a flexible or fluid toroidal mass undergoing minor axis rotational acceleration (accelerating "smoke ring" rotation) will tend to pull matter through the throat (a case of rotational frame dragging, acting through the throat).
A cyclic model (or oscillating model) is any of several cosmological models in which the universe follows infinite, or indefinite, self-sustaining cycles. For example, the oscillating universe theory briefly considered by Albert Einstein in 1930 theorized a universe following an eternal series of oscillations, each beginning with a Big Bang and ending with a Big Crunch; in the interim, the universe would expand for a period of time before the gravitational attraction of matter causes it to collapse back in and undergo a bounce. The opposite hypothesis is the finite-lifespan universe (noncyclic), and being a hypernym it includes many subtheories.
Hooke also did not provide accompanying evidence or mathematical demonstration. On these two aspects, Hooke stated in 1674: "Now what these several degrees [of gravitational attraction] are I have not yet experimentally verified" (indicating that he did not yet know what law the gravitation might follow); and as to his whole proposal: "This I only hint at present", "having my self many other things in hand which I would first compleat, and therefore cannot so well attend it" (i.e., "prosecuting this Inquiry"). In November 1679, Hooke began an exchange of letters with Newton, of which the full text is now published.
Most orbit modeling approaches model the two-body problem and then add models of these perturbing forces and simulate these models over time. Perturbing forces may include gravitational attraction from other bodies besides the primary, solar wind, drag, magnetic fields, and propulsive forces. Analytical solutions (mathematical expressions to predict the positions and motions at any future time) for simple two-body and three-body problems exist; none have been found for the n-body problem except for certain special cases. Even the two-body problem becomes insoluble if one of the bodies is irregular in shape.
A Zel'dovich pancake is a theoretical condensation of gas out of a primordial density fluctuation following the Big Bang. In 1970, Yakov B. Zel'dovich showed that for an ellipsoid of gas on a supergalactic scale, an approximation can be used that will model the collapse as occurring most rapidly along the shortest axis, resulting in a pancake form. This approximation assumes that the ellipsoid of gas is sufficiently large that the effect of pressure is negligible and only gravitational attraction needs to be considered. That is, the gas will collapse without being significantly perturbed by outward pressure.
According to classical physics, these massive stellar objects exert a gravitational attraction that is strong enough to prevent anything, even electromagnetic radiation, from escaping past the Schwarzschild radius. However, quantum mechanical effects are believed to potentially allow the emission of Hawking radiation at this distance. Electrons (and positrons) are thought to be created at the event horizon of these stellar remnants. When a pair of virtual particles (such as an electron and positron) is created in the vicinity of the event horizon, random spatial positioning might result in one of them to appear on the exterior; this process is called quantum tunnelling.
Observed structure of the Milky Way's spiral arms The Solar System orbits within the Milky Way, a barred spiral galaxy that is a prominent member of the Local Group of galaxies. It is a rotating mass of gas, dust, stars and other objects, held together by mutual gravitational attraction. As the Earth is located within the dusty outer arms, there are large portions of the Milky Way that are obscured from view. In the center of the Milky Way is the core, a bar-shaped bulge with what is believed to be a supermassive black hole at its center.
There is a memorial to his work at a location near Aurora, pictured here. His result suggested that the earth was more flattened towards the south pole than towards the north. George Everest, of the Indian Survey, while recuperating from an illness at the Cape nearly seventy years later, suggested that Lacaille's latitude observations had been affected by the gravitational attraction of Table Mountain at the southern end and by the Piketberg Mountain at the northern. In 1838, Thomas Maclear, who was Astronomer Royal at the Cape, repeated the measurements over a longer baseline and ultimately confirmed Everest's conjecture.
Michell's torsion balance, used in the Cavendish experiment Michell devised a torsion balance for measuring the mass of the Earth, but died before he could use it. His instrument passed into the hands of his lifelong friend Henry Cavendish, who first performed in 1798 the experiment now known as the Cavendish Experiment. Placing two 1-kg lead balls at the ends of a six-foot rod, he suspended the rod horizontally by a fibre attached to its centre. Then he placed a massive lead ball beside each of the small ones, causing a gravitational attraction that led the rod to turn clockwise.
Another model, proposed by David Eichler, now at Ben Gurion University, and later by Leo Blitz of the University of California at Berkeley, assumes the clouds are very massive, located between galaxies, and created when baryonic material pools near concentrations of dark matter. The gravitational attraction between the dark matter and the gas was intended to explain the ability of the clouds to remain stable even at intergalactic distances where the paucity of ambient material should cause the clouds to dissipate rather quickly. However, with the advent of distance determinations for most HVCs, this possibility may be ruled out.
For example, the Moon produces a greater tidal force on the Earth than the Sun, even though the Sun exerts a greater gravitational attraction on the Earth than the Moon, because the gradient is less. The tidal force is proportional to the mass of body causing it and to the radius of the body subjected to it. The Earth is 81 times more massive than the Moon but has roughly 4 times its radius. Therefore, at the same distance, the Earth produces a greater tidal force on the Moon, than the tidal force of the Moon on the Earth.
It is as though one took a photograph, which also recorded the instantaneous position and properties of motion. In contrast, a steady-state condition refers to a system's state being invariant to time; otherwise, the first derivatives and all higher derivatives are zero. of a group of celestial bodies, predict their interactive forces; and consequently, predict their true orbital motions for all future times.R. M. Rosenberg states the n-body problem similarly (see References): Each particle in a system of a finite number of particles is subjected to a Newtonian gravitational attraction from all the other particles, and to no other forces.
The force of gravity on Earth is the resultant (vector sum) of two forces: (a) The gravitational attraction in accordance with Newton's universal law of gravitation, and (b) the centrifugal force, which results from the choice of an earthbound, rotating frame of reference. The force of gravity is weakest at the equator because of the centrifugal force caused by the Earth's rotation and because points on the equator are furthest from the center of the Earth. The force of gravity varies with latitude and increases from about 9.780 m/s2 at the Equator to about 9.832 m/s2 at the poles.
One of the simplest examples of stellar engine is the Shkadov thruster (named after Dr. Leonid Shkadov who first proposed it), or a Class A stellar engine. Such an engine is a stellar propulsion system, consisting of an enormous mirror/light sail—actually a massive type of solar statite large enough to classify as a megastructure—which would balance gravitational attraction towards and radiation pressure away from the star. Since the radiation pressure of the star would now be asymmetrical, i.e. more radiation is being emitted in one direction as compared to another, the 'excess' radiation pressure acts as net thrust, accelerating the star in the direction of the hovering statite.
The world's largest potential source of sea level rise is the East Antarctic Ice Sheet, which holds enough ice to raise global sea levels by . The ice sheet has historically been considered to be relatively stable and has therefore attracted less scientific attention and observations compared to West Antarctica. A combination of satellite observations of its changing volume, flow and gravitational attraction with modelling of its surface mass balance suggests the overall mass balance of the East Antarctic Ice Sheet was relatively steady or slightly positive for much of the period 1992–2017. A 2019 study, however, using different methodology, concluded that East Antarctica is losing significant amounts of ice mass.
The Minor Planet Center classifies the trans-Neptunian object 90377 Sedna as a scattered-disc object. Its discoverer Michael E. Brown has suggested instead that it should be considered an inner Oort-cloud object rather than a member of the scattered disc, because, with a perihelion distance of 76 AU, it is too remote to be affected by the gravitational attraction of the outer planets. Under this definition, an object with a perihelion greater than 40 AU could be classified as outside the scattered disc. Sedna is not the only such object: (discovered before Sedna) and have a perihelion too far away from Neptune to be influenced by it.
His work remained largely unknown until similar models were made by Howard Robertson and Arthur Walker. Friedmann's model gave rise to three different types of models for the evolution of the Universe. First, the Universe would expand for a given amount of time, and if the expansion rate is less than the density of the Universe (leading to gravitational attraction), it would ultimately lead to the collapse of the Universe at a later stage. Secondly, the Universe would expand, and at some time, if the expansion rate and the density of the Universe became equal, it would expand slowly and stop, leading to a somewhat static Universe.
In gravity theories with extended supersymmetry (extended supergravities), a graviphoton is normally a superpartner of the graviton that behaves like a photon, and is prone to couple with gravitational strength, as was appreciated in the late 1970s. Unlike the graviton, however, it may provide a repulsive (as well as an attractive) force, and thus, in some technical sense, a type of anti-gravity. Under special circumstances, then, in several natural models, often descending from five-dimensional theories mentioned, it may actually cancel the gravitational attraction in the static limit. Joël Scherk investigated semirealistic aspects of this phenomenon, stimutlating searches for physical manifestations of this mechanism.
A binary system is a system of two astronomical bodies which are close enough that their gravitational attraction causes them to orbit each other around a barycenter (also see animated examples). More restrictive definitions require that this common center of mass is not located within the interior of either object, in order to exclude the typical planet–satellite systems and planetary systems. The most common binary systems are binary stars and binary asteroid, but brown dwarfs, planets, neutron stars, black holes and galaxies can also form binaries. A multiple system is like a binary system but consists of three or more objects such as for trinary stars and trinary asteroids.
Those regions with more matter will exert a greater gravitational force on their neighboring regions, and hence tend to draw in the surrounding material. This extra material makes them even more dense than before, increasing their gravitational attraction and further enhancing their pull on their neighbors. An irregular distribution of matter is therefore unstable under the influence of gravity, becoming more and more irregular as time goes by. This instability is exactly what is needed to explain the observation that the Universe is much more irregular now than at decoupling, and gravitational instability is almost universally accepted to be the primary influence leading to the formation of structures in the Universe.
Density wave theory is the preferred explanation for the well-defined structure of grand design spirals. According to this theory, the spiral arms are created inside density waves that turn around the galaxy at different speeds from the stars in the galaxy's disk. Stars and gas are clumped in these dense regions due to gravitational attraction towards the dense material, though their location in the spiral arm may not be permanent. When they come close to the spiral arm, they are pulled toward the dense material by the force of gravity; and as they travel through the arm, they are slowed from exiting by the same gravitational pull.
The solved, but simplified problem is then "perturbed" to make its time-rate-of-change equations for the object's position closer to the values from the real problem, such as including the gravitational attraction of a third, more distant body (the Sun). The slight changes that result from the terms in the equations – which themselves may have been simplified yet again – are used as corrections to the original solution. Because simplifications are made at every step, the corrections are never perfect, but even one cycle of corrections often provides a remarkably better approximate solution to the real problem. There is no requirement to stop at only one cycle of corrections.
Galileo rejected Kepler's explanation of the tides. Isaac Newton (1642–1727) was the first person to explain tides as the product of the gravitational attraction of astronomical masses. His explanation of the tides (and many other phenomena) was published in the Principia (1687) and used his theory of universal gravitation to explain the lunar and solar attractions as the origin of the tide-generating forces. Newton and others before Pierre- Simon Laplace worked the problem from the perspective of a static system (equilibrium theory), that provided an approximation that described the tides that would occur in a non-inertial ocean evenly covering the whole Earth.
In all inertial reference frames, while weightlessness is experienced, Newton's first law of motion is obeyed locally within the frame. Inside the frame (for example, inside an orbiting ship or free-falling elevator), unforced objects keep their velocity relative to the frame. Objects not in contact with other objects "float" freely. If the inertial trajectory is influenced by gravity, the reference frame will be an accelerated frame as seen from a position outside the gravitational attraction, and (seen from far away) the objects in the frame (elevator, etc.) will appear to be under the influence of a force (the so-called force of gravity).
Loop quantum cosmology (LQC) is a finite, symmetry-reduced model of loop quantum gravity (LQG) that predicts a "quantum bridge" between contracting and expanding cosmological branches. The distinguishing feature of LQC is the prominent role played by the quantum geometry effects of loop quantum gravity (LQG). In particular, quantum geometry creates a brand new repulsive force which is totally negligible at low space-time curvature but rises very rapidly in the Planck regime, overwhelming the classical gravitational attraction and thereby resolving singularities of general relativity. Once singularities are resolved, the conceptual paradigm of cosmology changes and one has to revisit many of the standard issues—e.g.
As resistance to disruption across stimulus contexts is analogous to the inertial mass of a moving object, behavioral momentum theory also suggests that preference in concurrent-chains procedures for one stimulus context over another is analogous to the gravitational attraction of two bodies (see Nevin & Grace, 2000). In concurrent-chains procedures, responding on the concurrently available initial links provides access to one of two mutually exclusive stimulus contexts called terminal links. As with multiple schedules, independent schedules of reinforcement can function in each terminal-link context. The relative allocation of responding across the two initial links indicates the extent to which an organism prefers one terminal-link context over the other.
General relativity (GR) is a theory of gravitation that was developed by Albert Einstein between 1907 and 1915, with contributions by many others after 1915. According to general relativity, the observed gravitational attraction between masses results from the warping of space and time by those masses. Before the advent of general relativity, Newton's law of universal gravitation had been accepted for more than two hundred years as a valid description of the gravitational force between masses, even though Newton himself did not regard the theory as the final word on the nature of gravity. Within a century of Newton's formulation, careful astronomical observation revealed unexplainable variations between the theory and the observations.
In the 1846 Andrew Motte translation of Newton's words:See the Principia on line at Andrew Motte Translation pp. 79-81 The argument that the motion is absolute, not relative, is incomplete, as it limits the participants relevant to the experiment to only the pail and the water, a limitation that has not been established. In fact, the concavity of the water clearly involves gravitational attraction, and by implication the Earth also is a participant. Here is a critique due to Mach arguing that only relative motion is established: The degree in which Mach's hypothesis is integrated in general relativity is discussed in the article Mach's principle; it is generally held that general relativity is not entirely Machian.
A hypothesis to the asteroid belt creation is that in general, in the Solar System, a planetary formation is thought to have occurred via a process comparable to the long-standing nebular hypothesis: a cloud of interstellar dust and gas collapsed under the influence of gravity to form a rotating disc of material that then further condensed to form the Sun and planets. During the first few million years of the Solar System's history, an accretion process of sticky collisions caused the clumping of small particles, which gradually increased in size. Once the clumps reached sufficient mass, they could draw in other bodies through gravitational attraction and become planetesimals. This gravitational accretion led to the formation of the planets.
John Leonard Riddell, a Professor of Chemistry in New Orleans, published the short story Orrin Lindsay's plan of aerial navigation, with a narrative of his explorations in the higher regions of the atmosphere, and his wonderful voyage round the moon! in 1847 on a pamphlet. It tells the story of the student Orrin Lindsay who invents an alloy that prevents gravitational attraction, and in a spherical craft leaves earth and travel to the moon. The story contains algebra and scientific footnotes, which makes it an early example of hard science fiction. William Henry Rhodes published in 1871 the tale The Case of Summerfield in the Sacramento Union newspaper, and introduced weapon of mass destruction.
Alfred Kleiner was professor of physics at the University of Zurich. He also held several other positions and titles throughout his career, including: Privatdozent (private lecturer) in 1870, Außerordentlicher Professor (Associate Professor) in 1880, Ordentlicher Professor (Full Professor) in 1885, Rektor (Chancellor) from 1908 to 1910, Honorarprofessor (Emeritus Professor) in 1915, and Privatdozent from 1875 to 1885 at the Swiss Federal Institute of Technology, also called Eidgenössische Technische Hochschule Zürich or ETH (the "Polytechnikum", also at Zurich). In the early 1890s, with his students Fritz Laager and Theordor Erismann Kleiner conducted experiments to determine if changes in gravitational attraction could be caused by shielding. No effect greater than the experimental error was observed.
The gravitational attraction that the Moon exerts on Earth is the cause of tides in the sea; the Sun has a smaller tidal influence. If Earth had a global ocean of uniform depth, the Moon would act to deform both the solid Earth (by a small amount) and the ocean in the shape of an ellipsoid with the high points roughly beneath the Moon and on the opposite side of Earth. However, because of the presence of the continents, Earth's much faster rotation and varying ocean depths, this simplistic visualisation does not happen. Although the tidal flow period is generally synchronized to the Moon's orbit around Earth, its relative timing varies greatly.
Larger objects distort into an ovoid, and are slightly compressed, which is what happens to the Earth's oceans under the action of the Moon. The Earth and Moon rotate about their common center of mass or barycenter, and their gravitational attraction provides the centripetal force necessary to maintain this motion. To an observer on the Earth, very close to this barycenter, the situation is one of the Earth as body 1 acted upon by the gravity of the Moon as body 2. All parts of the Earth are subject to the Moon's gravitational forces, causing the water in the oceans to redistribute, forming bulges on the sides near the Moon and far from the Moon.
A pendulum hangs straight downwards in a symmetrical gravitational field. However, if a sufficiently large mass such as a mountain is nearby, its gravitational attraction should pull the pendulum's plumb-bob slightly out of true (in the sense that it doesn't point to the centre of mass of the Earth). The change in plumb-line angle against a known object—such as a star—could be carefully measured on opposite sides of the mountain. If the mass of the mountain could be independently established from a determination of its volume and an estimate of the mean density of its rocks, then these values could be extrapolated to provide the mean density of the Earth, and by extension, its mass.
A bulge is formed in the ocean at the place where the Earth is closest to the Moon, because it is also where the effect of the Moon's gravity is stronger. On the opposite side of the Earth, the lunar force is at its weakest and this causes another bulge to form. As the Moon rotates around the Earth, so do these ocean bulges move around the Earth. The gravitational attraction of the Sun is also working on the seas, but its effect on tides is less powerful than that of the Moon, and when the Sun, Moon and Earth are all aligned (full moon and new moon), the combined effect results in the high "spring tides".
The creatures that moved or copied humanity are unknown, as is the technology they used and the purpose for their action. Because of the projection of a spherical surface onto a flat surface, some changes occur: North America is now much farther from Asia, as there is no polar route. Furthermore, launching an artificial satellite into orbit becomes impossible, and chemical-fuelled ICBMs are no longer capable of reaching other continents. The gravitational attraction in the near field of an Alderson disk does not drop away according to the inverse-square law but is approximately constant and perpendicular to the disk, so missile trajectories become parabolic rather than segments of elliptical orbits.
The Big Crunch scenario hypothesized that the density of matter throughout the universe is sufficiently high that gravitational attraction will overcome the expansion which began with the Big Bang. The FLRW cosmology can predict whether the expansion will eventually stop based on the average energy density, Hubble parameter, and cosmological constant. If the metric expansion stopped, then contraction will inevitably follow, accelerating as time passes and finishing the universe in a kind of gravitational collapse. A more specific theory called "Big Bounce" proposes that the universe could collapse to the state where it began and then initiate another Big Bang, so in this way the universe would last forever, but would pass through phases of expansion (Big Bang) and contraction (Big Crunch).
Although Sedna is officially considered a scattered-disc object by the MPC, its discoverer Michael E. Brown has suggested that because its perihelion distance of 76 AU is too distant to be affected by the gravitational attraction of the outer planets it should be considered an inner-Oort-cloud object rather than a member of the scattered disc. This classification of Sedna as a detached object is accepted in recent publications. This line of thinking suggests that the lack of a significant gravitational interaction with the outer planets creates an extended–outer group starting somewhere between Sedna (perihelion 76 AU) and more conventional SDOs like (perihelion 35 AU), which is listed as a scattered–near object by the Deep Ecliptic Survey.
As for Brans–Dicke (which has a tunable parameter ω such that ω = ∞ is the same as general relativity), the amount by which it can differ from general relativity has been severely constrained by these observations. In addition, general relativity is inconsistent with quantum mechanics, the physical theory that describes the wave–particle duality of matter, and quantum mechanics does not currently describe gravitational attraction at relevant (microscopic) scales. There is a great deal of speculation in the physics community as to the modifications that might be needed to both general relativity and quantum mechanics in order to unite them consistently. The speculative theory that unites general relativity and quantum mechanics is usually called quantum gravity, prominent examples of which include String Theory and Loop Quantum Gravity.
As Europa comes slightly nearer to Jupiter, Jupiter's gravitational attraction increases, causing Europa to elongate towards and away from it. As Europa moves slightly away from Jupiter, Jupiter's gravitational force decreases, causing Europa to relax back into a more spherical shape, and creating tides in its ocean. The orbital eccentricity of Europa is continuously pumped by its mean-motion resonance with Io. Thus, the tidal flexing kneads Europa's interior and gives it a source of heat, possibly allowing its ocean to stay liquid while driving subsurface geological processes. The ultimate source of this energy is Jupiter's rotation, which is tapped by Io through the tides it raises on Jupiter and is transferred to Europa and Ganymede by the orbital resonance.
Augustus Edward Hough Love FRS (17 April 1863, Weston-super-Mare – 5 June 1940, Oxford), often known as A. E. H. Love, was a mathematician famous for his work on the mathematical theory of elasticity. He also worked on wave propagation and his work on the structure of the Earth in Some Problems of Geodynamics won for him the Adams prize in 1911 when he developed a mathematical model of surface waves known as Love waves. Love also contributed to the theory of tidal locking and introduced the parameters known as Love numbers, which are widely used today. These numbers are also used in problems related to the tidal deformation of the Earth due to the gravitational attraction of the Moon and Sun.
While examining the Coma galaxy cluster in 1933, Zwicky was the first to use the virial theorem to discover the existence of a gravitational anomaly, which he termed dunkle (kalt) Materie 'dark matter'. The gravitational anomaly surfaced due to the excessive rotational velocity of luminous matter compared to the calculated gravitational attraction within the cluster. He calculated the gravitational mass of the galaxies within the cluster from the observed rotational velocities and obtained a value at least 400 times greater than expected from their luminosity. The same calculation today shows a smaller factor, based on greater values for the mass of luminous material; but it is still clear that the great majority of matter was correctly inferred to be dark.
He was active in the Council of the Royal Society of London (to which he was elected in 1765). His interest and expertise in the use of scientific instruments led him to head a committee to review the Royal Society's meteorological instruments and to help assess the instruments of the Royal Greenwich Observatory. His first paper, Factitious Airs, appeared in 1766. Other committees on which he served included the committee of papers, which chose the papers for publication in the Philosophical Transactions of the Royal Society, and the committees for the transit of Venus (1769), for the gravitational attraction of mountains (1774), and for the scientific instructions for Constantine Phipps's expedition (1773) in search of the North Pole and the Northwest Passage.
For spacecraft missions where large changes in the direction of flight are necessary, direct propulsion by the spacecraft may not be feasible due to the large delta-v requirement. In these cases it may be possible to perform a flyby of a nearby planet or moon, using its gravitational attraction to alter the ship's direction of flight. Although this maneuver is very similar to the gravitational slingshot it differs in that a slingshot often implies a change in both speed and direction whereas the gravity turn only changes the direction of flight. A variant of this maneuver, the free return trajectory allows the spacecraft to depart from a planet, circle another planet once, and return to the starting planet using propulsion only during the initial departure burn.
In recent decades the institute has concentrated on sea level monitoring and prediction around UK coasts, and indeed on understanding sea level changes worldwide: the Permanent Service for Mean Sea Level having been established at Bidston by Proudman in 1933 and as important as ever today. Such understanding informs government departments on policies for coastal protection, and contributes to international scientific study groups such as those of the Intergovernmental Panel on Climate Change (IPCC). Thanks to the work of Doodson and other scientists in Liverpool, the tide can be predicted at any location around the UK with several centimetre accuracy. Superimposed upon the ‘astronomical tide’, which is caused by the gravitational attraction of the Moon and Sun, is the ‘storm surge’ caused by strong winds and low air pressures.
Even following the adoption of Copernicus's heliocentric model of the universe, new versions of the celestial sphere model were introduced, with the planetary spheres following this sequence from the central Sun: Mercury, Venus, Earth-Moon, Mars, Jupiter and Saturn. Mainstream belief in the theory of celestial spheres did not survive the Scientific Revolution. In the early 1600s, Kepler continued to discuss celestial spheres, although he did not consider that the planets were carried by the spheres but held that they moved in elliptical paths described by Kepler's laws of planetary motion. In the late 1600s, Greek and medieval theories concerning the motion of terrestrial and celestial objects were replaced by Newton's law of universal gravitation and Newtonian mechanics, which explain how Kepler's laws arise from the gravitational attraction between bodies.
More recent closeup images from the Cassini probe show that the F Ring consists of one core ring and a spiral strand around it. They also show that when Prometheus encounters the ring at its apoapsis, its gravitational attraction creates kinks and knots in the F Ring as the moon 'steals' material from it, leaving a dark channel in the inner part of the ring (see video link and additional F Ring images in gallery). Since Prometheus orbits Saturn more rapidly than the material in the F ring, each new channel is carved about 3.2 degrees in front of the previous one. In 2008, further dynamism was detected, suggesting that small unseen moons orbiting within the F Ring are continually passing through its narrow core because of perturbations from Prometheus.
Heller and Armstrong proposed that a series of basic characteristics are required to classify an exoplanet or exomoon as superhabitable; for size, it is required to be about 2 Earth masses, and 1.3 Earth radii will provide an optimal size for plate tectonics. In addition, it would have a greater gravitational attraction that would increase retention of gases during the planet's formation. It is therefore likely that they have a denser atmosphere that will offer greater concentration of oxygen and greenhouse gases, which in turn raise the average temperature to optimum levels for plant life to about . A denser atmosphere may also influence the surface relief, making it more regular and decreasing the size of the ocean basins, which would improve diversity of marine life in shallow waters.
An elliptic Kepler orbit with an eccentricity of 0.7, a parabolic Kepler orbit and a hyperbolic Kepler orbit with an eccentricity of 1.3. The distance to the focal point is a function of the polar angle relative to the horizontal line as given by the equation () In celestial mechanics, a Kepler orbit (or Keplerian orbit, named after the German astronomer Johannes Kepler) is the motion of one body relative to another, as an ellipse, parabola, or hyperbola, which forms a two-dimensional orbital plane in three-dimensional space. A Kepler orbit can also form a straight line. It considers only the point-like gravitational attraction of two bodies, neglecting perturbations due to gravitational interactions with other objects, atmospheric drag, solar radiation pressure, a non-spherical central body, and so on.
However, the model is valid only on large scales (roughly the scale of galaxy clusters and above), because gravitational attraction binds matter together strongly enough that metric expansion cannot be observed on a smaller scale at this time. As such, the only galaxies receding from one another as a result of metric expansion are those separated by cosmologically relevant scales larger than the length scales associated with the gravitational collapse that are possible in the age of the universe given the matter density and average expansion rate. Physicists have postulated the existence of dark energy, appearing as a cosmological constant in the simplest gravitational models, as a way to explain the acceleration. According to the simplest extrapolation of the currently-favored cosmological model, the Lambda-CDM model, this acceleration becomes more dominant into the future.
Independently of its actual nature, dark energy would need to have a strong negative pressure (repulsive action), like radiation pressure in a metamaterial, to explain the observed acceleration of the expansion of the universe. According to general relativity, the pressure within a substance contributes to its gravitational attraction for other objects just as its mass density does. This happens because the physical quantity that causes matter to generate gravitational effects is the stress–energy tensor, which contains both the energy (or matter) density of a substance and its pressure and viscosity. In the Friedmann–Lemaître–Robertson–Walker metric, it can be shown that a strong constant negative pressure in all the universe causes an acceleration in the expansion if the universe is already expanding, or a deceleration in contraction if the universe is already contracting.
The projectile begins to move away from the Moon, towards the 'dead point' (the place at which the gravitational attraction of the Moon and Earth becomes equal). Michel Ardan hits upon the idea of using the rockets fixed to the bottom of the projectile (which they were originally going to use to deaden the shock of landing) to propel the projectile towards the Moon and hopefully cause it to fall onto it, thereby achieving their mission. When the projectile reaches the point of neutral attraction, the rockets are fired, but it is too late. The projectile begins a fall onto the Earth from a distance of , and it is to strike the Earth at a speed of , the same speed at which it left the mouth of the Columbiad.
The first three attempts by the U.S. to perform a successful hard Moon landing with a ruggedized seismometer package in 1962 all failed. The Soviets first achieved the milestone of a hard lunar landing with a ruggedized camera in 1966, followed only months later by the first uncrewed soft lunar landing by the U.S. The speed of a crash landing on its surface is typically between 70 and 100% of the escape velocity of the target moon, and thus this is the total velocity which must be shed from the target moon's gravitational attraction for a soft landing to occur. For Earth's Moon, the escape velocity is . The change in velocity (referred to as a delta-v) is usually provided by a landing rocket, which must be carried into space by the original launch vehicle as part of the overall spacecraft.
Woodward claims that his hypothesis predicts physical forces that he calls Mach effects but are usually referred to as the Woodward effect. He says that his hypothesis is based on Mach's principle that posits inertia, the resistance of mass to acceleration, is a result of the mutual gravitational attraction of all matter in the universe. Thus, if the mass of a given object can be varied while being oscillated either in a linear or orbital path, such that the mass is high while the mass is moving in one direction and low while moving back, then the net effect should be acceleration in one direction as the inertial drag of the universe upon the object varies as its mass varies. If a spacecraft engine could be designed to exploit it then acceleration could be produced without using rocket engine propellants.
After Michell's death in 1793, Herschel bought a ten-foot-long, 30-inch reflecting telescope from Michell's estate. In 1797, Herschel measured many of the systems again, and discovered changes in their relative positions that could not be attributed to the parallax caused by the Earth's orbit. He waited until 1802 (in Catalogue of 500 new Nebulae, nebulous Stars, planetary Nebulae, and Clusters of Stars; with Remarks on the Construction of the Heavens) to announce the hypothesis that the two stars might be "binary sidereal systems" orbiting under mutual gravitational attraction, a hypothesis he confirmed in 1803 in his Account of the Changes that have happened, during the last Twenty- five Years, in the relative Situation of Double-stars; with an Investigation of the Cause to which they are owing. In all, Herschel discovered over 800 confirmedWilliam Herschel's Double Star Catalog. Handprint.
The work was carried out by a core team of 14 Australia-based astronomers led by Chris Blake and including Sarah Brough, Warrick Couch, Karl Glazebrook, Greg Poole, Tamara Davis, Michael Drinkwater, Russell Jurek, Kevin Pimbblet, Matthew Colless, Rob Sharp, Scott Croom, Michael Pracy, David Woods, Barry Madore, Chris Martin and Ted Wyder. The work was done in conjunction with collaborators in Toronto, Canada and at the California Institute of Technology and Jet Propulsion Laboratory in the United States. The underlying purpose of the survey was to improve understanding of the phenomenon of "dark energy", proposed as the mechanism for the observed increasing rate of expansion of the universe, contradicting the traditional theories of gravitational attraction. The survey results can be used in conjunction with measurements of Cosmic microwave background (CMB) to provide more accurate estimates of the composition of the universe.
The most massive stars, especially rapidly rotating stars with enhanced convection and mixing, may skip these steps and move directly to the Wolf–Rayet stage. This means that stars at the top of the Hertzsprung–Russell diagram where hypergiants are found may be newly evolved from the main sequence and still with high mass, or much more evolved post-red supergiant stars that have lost a significant fraction of their initial mass, and these objects cannot be distinguished simply on the basis of their luminosity and temperature. High- mass stars with a high proportion of remaining hydrogen are more stable, while older stars with lower masses and a higher proportion of heavy elements have less stable atmospheres due to increased radiation pressure and decreased gravitational attraction. These are thought to be the hypergiants, near the Eddington limit and rapidly losing mass.
This was followed by a paper co-written with one of his students, George Volkoff, "On Massive Neutron Cores", in which they demonstrated that there was a limit, the so-called Tolman–Oppenheimer–Volkoff limit, to the mass of stars beyond which they would not remain stable as neutron stars and would undergo gravitational collapse. Finally, in 1939, Oppenheimer and another of his students, Hartland Snyder, produced a paper "On Continued Gravitational Attraction", which predicted the existence of what are today known as black holes. After the Born–Oppenheimer approximation paper, these papers remain his most cited, and were key factors in the rejuvenation of astrophysical research in the United States in the 1950s, mainly by John A. Wheeler. Oppenheimer's papers were considered difficult to understand even by the standards of the abstract topics he was expert in.
Fatio therefore failed to interest Huygens (who believed in the conservation of vis viva) in his proposal. Huygens may also have found Fatio's theory uncongenial because it assumed an empty space in which the aetherial corpuscles moved, a view contrary to the plenism of Huygens and Leibniz, who conceived of the aether as a fluid pervading all of space. Finding that the drag resistance was proportional to the product of the speed and the density of the aetherial corpuscles, while the gravitational attraction was proportional to the density and the square of the speed of the corpuscles, Fatio concluded that the drag could be made negligible by decreasing the density while increasing the speed. However, despite some initial enthusiasm on the part of Newton and Halley, Fatio's theory of gravity soon fell into oblivion and Newton abandoned all attempts to explain gravity in terms of contact interactions.
Inspired by the circular restricted three-body problem, the four-body problem can be greatly simplified by considering a smaller body to have a small mass compared to the other three massive bodies, which in turn are approximated to describe circular orbits. This is known as the bicircular restricted four-body problem (also known as bicircular model) and it can be traced back to 1960 in a NASA report written by Su-Shu Huang. This formulation has been highly relevant in the astrodynamics, mainly to model spacecraft trajectories in the Earth-Moon system with the addition of the gravitational attraction of the Sun. The former formulation of the bicircular restricted four-body problem can be problematic when modelling other systems that not the Earth-Moon-Sun, so the formulation was generalized by Negri and Prado to expand the application range and improve the accuracy without loss of simplicity.
Consequent detections of H+, O+, Ne+, and N+ have been made several years later with the SWICS instrument on board the Ulysses spacecraft. The observations of interstellar pickup ions close to Earth allow to investigate the gas dynamics of the local interstellar medium, which otherwise can only be inferred remotely via optical observations or by a direct measurement of the interstellar neutral gas. The relative velocity of the local interstellar medium with respect to the Sun, temperature and density can be inferred from the spatial pattern of the observed pickup ion fluxes. In particular the pickup ion focusing cone, which is an enhancement of interstellar pickup ions that is co-aligned with the velocity vector of the interstellar neutral atoms (He+ and Ne+), forms due to the Sun's gravitational attraction and can be used to infer the inflow direction of the local interstellar medium.
The equivalence principle, in its simplest form, asserts that the trajectories of falling bodies in a gravitational field should be independent of their mass and internal structure, provided they are small enough not to disturb the environment or be affected by tidal forces. This idea has been tested to extremely high precision by Eötvös torsion balance experiments, which look for a differential acceleration between two test masses. Constraints on this, and on the existence of a composition-dependent fifth force or gravitational Yukawa interaction are very strong, and are discussed under fifth force and weak equivalence principle. A version of the equivalence principle, called the strong equivalence principle, asserts that self-gravitation falling bodies, such as stars, planets or black holes (which are all held together by their gravitational attraction) should follow the same trajectories in a gravitational field, provided the same conditions are satisfied.
The corotation circle takes on particular importance in reference to dark matter. In barred spiral galaxies (our Milky Way could be a galaxy of this type according to the most recent studies), the stars arranged along the bar structures rotate faster than those arranged along the arm structures, due to gravitational attraction. It has been calculated that if the radius of corotation were placed at a distance from the center of the galaxy greater than 1.4 times the length of the bar, this would constitute evidence that the rotation of the galaxy is curbed by dark matter halos, which are supposed to permeate space around the galaxy. All the measurements made, where galaxies have made it possible, have so far placed the circles of corotation at distances of less than 1.4, which would lead to the conclusion that dark matter does not significantly influence galactic rotation.
As well as helping determine the parallax of 61 Cygni, Bessel's precise measurements using a new meridian circle from Adolf Repsold allowed him to notice deviations in the motions of Sirius and Procyon, which he deduced must be caused by the gravitational attraction of unseen companions. His announcement of Sirius's "dark companion" in 1844 was the first correct claim of a previously unobserved companion by positional measurement, and eventually led to the discovery of Sirius B. Bessel was the first scientist who realized the effect later called personal equation, that several simultaneously observing persons determine slightly different values, especially recording the transition time of stars. In 1824, Bessel developed a new method for calculating the circumstances of eclipses using the so-called Besselian elements. His method simplified the calculation to such an extent, without sacrificing accuracy, that it is still in use today. Bessel's work in 1840 contributed to the discovery of Neptune in 1846 at Berlin Observatory, several months after Bessel's death.
In collaboration with Murray Gell-Mann and others, Hartle developed an alternative to the standard Copenhagen interpretation, more general and appropriate to quantum cosmology, based on consistent histories. With Dieter Brill in 1964, he discovered the Brill–Hartle geon, an approximate solution realizing Wheeler's suggestion of a hypothetical phenomenon in which a gravitational wave packet is confined to a compact region of spacetime by the gravitational attraction of its own field energy. With Kip Thorne, Hartle derived from general relativity the laws of motion and precession of black holes and other relativistic bodies, including the influence of the coupling of their multipole moments to the spacetime curvature of nearby objects, as well as writing down the Hartle-Thorne metric, an approximate solution which describes the exterior of a slowly and rigidly rotating, stationary and axially symmetric body. Working at the Enrico Fermi Institute at the University of Chicago in 1983, he developed the Hartle–Hawking wavefunction of the Universe in collaboration with Stephen Hawking.
Hektor is one of the most elongated bodies of its size in the Solar System, being approximately 403 km in its longest dimension, but averaging only around 201 km in its other dimensions, with a total volume equivalent to an approx 250 km diameter sphere, and an estimated mass of (thus density of 1.0g/cm3). It is thought that Hektor might be a contact binary (two asteroids joined by gravitational attraction) like 216 Kleopatra, composed of two more rounded lobes of 220 and 183 km mean diameters. Hubble Space Telescope observations of Hektor in 1993 did not show an obvious bilobate shape because of a limited angular resolution. On 17 July 2006, the Keck 10-meter-II-telescope and its laser guide star adaptive optics (AO) system indicated a bilobate shape for Hektor, which was reinforced by later studies that, together with multiple historical lightcurves, suggest a rotation period of 6.9205 hours.
In that theory, the mass of electrons (or, more generally, leptons) is modified by including the mass contributions of virtual photons, in a technique known as renormalization. Such "radiative corrections" contribute to a number of predictions of QED, such as the magnetic dipole moment of leptons, the Lamb shift, and the hyperfine structure of bound lepton pairs, such as muonium and positronium.Radiative correction to electron mass section 7-1-2, anomalous magnetic moments section 7-2-1, Lamb shift section 7-3-2 and hyperfine splitting in positronium section 10-3 in Since photons contribute to the stress–energy tensor, they exert a gravitational attraction on other objects, according to the theory of general relativity. Conversely, photons are themselves affected by gravity; their normally straight trajectories may be bent by warped spacetime, as in gravitational lensing, and their frequencies may be lowered by moving to a higher gravitational potential, as in the Pound–Rebka experiment.
" Blumenbach compared the uncertainty about the origin and ultimate nature of the formative drive to similar uncertainties about gravitational attraction: "just in the same way as we use the name of attraction or gravity to denote certain forces, the causes of which however still remain hid, as they say, in Cimmerian darkness, the formative force (nisus formativus) can explain the generation of animals." At the same time, befitting the central idea of the science and medicine of dynamic polarity, it was also the physiological functional identity of what theorists of society or mind called "aspiration." "Blumenbach's Bildungstrieb found quick passage into evolutionary theorizing of the decade following its formulation and in the thinking of the German natural philosophers (p. 245) One of Blumenbach's contemporaries, Samuel Hahnemann, undertook to study in detail how this generative, reproductive and creative power, which he termed the Erzeugungskraft of the Lebenskraft of living power of the organism, could be negatively affected by inimical agents to engender disease.
In the same work, Newton presented a calculus- like method of geometrical analysis using 'first and last ratios', gave the first analytical determination (based on Boyle's law) of the speed of sound in air, inferred the oblateness of Earth's spheroidal figure, accounted for the precession of the equinoxes as a result of the Moon's gravitational attraction on the Earth's oblateness, initiated the gravitational study of the irregularities in the motion of the Moon, provided a theory for the determination of the orbits of comets, and much more. Newton made clear his heliocentric view of the Solar System—developed in a somewhat modern way because already in the mid-1680s he recognised the "deviation of the Sun" from the centre of gravity of the Solar System.See Curtis Wilson, "The Newtonian achievement in astronomy", pp. 233–274 in R Taton & C Wilson (eds) (1989) The General History of Astronomy, Volume, 2A', at p. 233.
Franklin Hall was a normal human until empowered by an explosion that intermingled his molecules with sub-nuclear graviton particles generated by a nearby particle generator, which gave him the ability to manipulate gravitons (the subatomic particles that carry the force of gravitational attraction) and anti-gravitons (similar particles but with opposite force and spin of gravitons). Graviton could surround any person or object, including himself, with gravitons or anti-gravitons, thereby increasing or decreasing the pull of gravity upon it. Hall was able to manipulate gravitons for various uses, including the projection of highly concussive blasts, formation of gravitational force fields and levitation, and had also been proven capable of generating gravitational fields in various objects, making them attract any nearby matter (or individuals) not heavy enough or physically strong enough to resist. By decreasing the pull of gravity beneath him, then manipulating its direction of effect, he could fly at any speed or height at which he could still breathe.
However, this does not cause the objects to grow steadily or to disintegrate; unless they are very weakly bound, they will simply settle into an equilibrium state which is slightly (undetectably) larger than it would otherwise have been. As the universe expands and the matter in it thins, the gravitational attraction decreases (since it is proportional to the density), while the cosmological repulsion increases; thus the ultimate fate of the ΛCDM universe is a near vacuum expanding at an ever-increasing rate under the influence of the cosmological constant. However, the only locally visible effect of the accelerating expansion is the disappearance (by runaway redshift) of distant galaxies; gravitationally bound objects like the Milky Way do not expand and the Andromeda galaxy is moving fast enough towards us that it will still merge with the Milky Way in 3 billion years time, and it is also likely that the merged supergalaxy that forms will eventually fall in and merge with the nearby Virgo Cluster. However, galaxies lying farther away from this will recede away at ever-increasing speed and be redshifted out of our range of visibility.
A discovery made in 1672-1673 by Jean Richer turned the attention of mathematicians to the deviation of the Earth's shape from a spherical form. This astronomer, having been sent by the Academy of Sciences of Paris to Cayenne, in South America, for the purpose of investigating the amount of astronomical refraction and other astronomical objects, notably the parallax of Mars between Paris and Cayenne in order to determine the Earth-Sun distance, observed that his clock, which had been regulated at Paris to beat seconds, lost about two minutes and a half daily at Cayenne, and that in order to bring it to measure mean solar time it was necessary to shorten the pendulum by more than a line (about 1⁄12th of an in.). This fact was scarcely credited till it had been confirmed by the subsequent observations of Varin and Deshayes on the coasts of Africa and America. In South America Bouguer noticed, as did George Everest in the 19th century Great Trigonometric Survey of India, that the astronomical vertical tended to be pulled in the direction of large mountain ranges, due to the gravitational attraction of these huge piles of rock.

No results under this filter, show 197 sentences.