Gravity Travels At The Speed Of Light

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Gravity Travels At The Speed Of Light – The gravitational lens illustration shows how the background galaxy—or any light path—… [+] is distorted by the presence of intervening matter, but also shows how space itself is bent and distorted by the presence of foreground matter itself. Before Einstein proposed his theory of general relativity, he understood that this bending must occur, although many remained skeptical until (and even after) the 1919 solar eclipse confirmed his prediction.

What happens to light when it passes near a large mass? Does it just continue in a straight line, not deviating from its original track? Does it experience a force due to the gravitational effect of the surrounding matter? And if so, what is the magnitude of the force it experiences?

Gravity Travels At The Speed Of Light

Gravity Travels At The Speed Of Light

These questions go to the heart of how gravity works. This year 2019 marks 100 years since the confirmation of General Relativity. Two independent teams made a successful expedition to measure the position of stars near the edge of the Sun during a total solar eclipse on May 29, 1919. Using the highest quality observations allowed by technology at the time, they determined whether the light of this distant star was bent. by the Sun’s gravity and how much. It was a decision that surprised many, but Einstein already knew what the answer was. Here is the tutorial.

Have We Made An Object That Could Travel 1% The Speed Of Light?

Examples/illustrations of gravitational lensing and the bending of starlight by matter. Before… [+] any quantitative predictions were made, even before Einstein worked on the theory, he knew that light must be bent by matter.

Imagine you are in an elevator and all the doors are closed. You can hear the engine running outside, but you can’t see what’s going on outside of you. All you know is what you can feel and what you can see in the elevator car. Now you try to ask the most physically meaningful question you can. How fast are you moving and in which direction? Does your movement change or not? And if so, what causes it?

From inside the elevator, unable to see what’s going on outside, you can’t know the answer to almost any of these questions. According to the laws of relativity – from before Einstein to Galileo – you cannot tell whether you are moving or not.

A light clock, consisting of photons bouncing between two mirrors, will tell the time to each observer… [+] Although two observers may disagree about how much time has passed, they will agree on the laws of physics and the constants of the universe, like the speed of light. Not only would each observer see time passing at the same rate for themselves one second at a time, but they would be unable to learn anything about the outside world from their own limited frame of reference.

Where Do Space, Time And Gravity Come From?

The laws of physics don’t depend on your speed, and there’s no measurement you can just take from inside an elevator that will tell you what that speed is relative to the outside world. Your elevator can move up, down, horizontally or in any direction; if there is no change in its motion, it will have no physical effect on anything that happens in the elevator.

This is the principle of relativity: all inertial (non-accelerating) frames of reference obey the same laws and equations of physics. The properties of the Universe in a stationary elevator and an elevator in constant motion are indistinguishable to any observer. Only if you can look outside and compare your movements to something external will there be a way to know how you are moving.

The Soyuz-2.1a rocket took off on April 19, 2013 with Bion-M No. 1. The rockets don’t accelerate much… [+] faster than a car or an object in free fall to Earth, but they can maintain that acceleration for minutes at a time, allowing them to break the Earth’s gravitational bonds. For an observer inside, they will experience a constant acceleration force, but will not be able to determine its origin. Once the acceleration stops, they won’t know how fast they are going unless they can observe the outside world.

Gravity Travels At The Speed Of Light

The idea that there is no such thing as absolute motion is at the heart of special relativity: all non-accelerating observers can have the same claim to have their perspective correct.

Third Gravitational Wave Detection, From Black Hole Merger 3 Billion Light Years Away

. When you’re in a vehicle that’s rapidly accelerating (and feeling like you’re being pushed back into your seat) or decelerating (which propels you forward), you experience an effect similar to what someone would feel in a speeding elevator. It’s the change in motion—the acceleration—that causes what you experience as a force, as you’d expect from Newton’s most famous equation:

When a vehicle experiences accelerated motion, instead of constant motion, the driver and all… [+] passengers experience a force equal to their weight multiplied by the rate of acceleration. Even in a closed system where you cannot see or observe the outside world, there will be forces that allow you to conclude that your experience is consistent with a certain acceleration.

Now let’s move on to another problem. If you were in the same elevator, but instead of accelerating, it was sitting still on the surface of the Earth, what would you experience from the inside?

— on the surface of our planet. If the elevator is standing on the ground, Earth’s gravity still causes every object in it to accelerate downward at 9.8 m/s.

Why Does Gravity Travel At The Speed Of Light?

: the same result as if the elevator were accelerating upwards at this rate. For a person in an elevator, with no way to see the outside world and no way to know if it is stationary, but with a gravitational field or acceleration due to external thrust, this scenario would be the same.

The same behavior of a ball falling to the floor in an accelerated rocket (left) and on Earth… [+] (right) is an example of Einstein’s equivalence principle. Measuring acceleration at a point does not differentiate between gravitational acceleration and other forms of acceleration; unless you can somehow observe or access information about the outside world, both scenarios will produce the same experimental results.

Now think about what would happen if you allowed a beam of light from outside to enter one side of the elevator through the hole and notice where it hit the wall on the other side. This depends on both your speed and acceleration relative to the external light source. Mainly:

Gravity Travels At The Speed Of Light

However, this last case describes both an accelerating lift and a stationary lift in a gravitational field.

Would You Really Age More Slowly On A Spaceship At Close To Light Speed?

If you allow light in from outside your environment, you can get information about the… [+] relative velocity and acceleration of two reference frames. The cause of the acceleration, whether from inertial (thrust) or gravitational effects, cannot be distinguished from this observation alone.

This is the basis of Einstein’s equivalence principle: the idea that an observer cannot distinguish between acceleration due to the effects of gravity or inertia (drag). In extreme cases, jumping from a building with no air resistance will feel like complete weightlessness.

For example, astronauts on the International Space Station experience complete weightlessness even though the Earth accelerates them toward its center at about 90% of the force we experience on its surface. Einstein later called this realization, which struck him in 1911, his happiest thought. It was this idea that led him, after four years of further development, to the publication of the General Theory of Relativity.

Astronauts and fruits on the International Space Station. Note that gravity is not turned off, … [+], but everything – including the spacecraft – is uniformly accelerated, resulting in a zero g experience. The ISS is an example of an inertial frame of reference.

This Is Why Einstein Knew That Gravity Must Bend Light

The conclusion of Einstein’s thought experiment is undeniable. Whatever effect gravity has on a particular location in space—whatever acceleration it causes—will also affect light. Just as accelerating your elevator with thrust causes a beam of light to be deflected, accelerating it by placing it near a gravitational mass causes the same deflection.

Therefore, Einstein reasoned that not only can it be predicted that light rays cannot follow a straight path when in a gravitational field, but the magnitude of the deflection can be calculated simply by knowing the strength of the gravitational effect in the gravitational field. is around that mass.

During a total eclipse, the stars will appear to be in a different position than their true position… [+], due to the bending of light from an intermediate mass: the Sun. The magnitude of the deflection will be determined by the strength of the gravitational effect on the points in space through which the light rays pass.

Gravity Travels At The Speed Of Light

Einstein had his most exciting idea in 1911, and by the end of 1915 he had completed the formulation of his General Theory of Relativity, which would lead to clear predictions about how much light should be deflected for stars.

New Theories Take Flight On Speed Of Gravity, Light / Einstein’s Assumptions May Be Start Of Downfall

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