All Questions
Tagged with speed-of-light gravity
181
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What is a simple example that contradicts the theory that light (photons) could have a super small mass? [duplicate]
The obvious example is that, to bring something that has mass to the speed $c$ requires infinite energy due to special relativity. But what if a kid asked me "What if light/photos had a super ...
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2
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How could I calculate the time it will take for light and mass to go towards a black hole and come back, to and from constant radial distances?
If you have a "perfect mirror" and a "perfect trampoline" at some constant distance outside a black hole's event horizon:
a) How would a shell observer at some distance farther ...
- 171
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85
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Questions about speed of gravity [duplicate]
If gravity "travels" at $c$, and the sun is travelling "forward", does it mean the planets are actually orbiting various points "behind" the center of the sun? Does it ...
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3
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The speed of an impulse transmitted along a string
A supernova explosion on the far side of the Sun ejects a mass with approximately the same mass of the Sun directly at the back side of the Sun. If this ejected mass is travelling arbitrarily close to ...
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69
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Does squeezed light gravitate repulsively? [closed]
Since there are alternate regions of positive and negative energy densities in squeezed light, does that mean that the negative energy density parts gravitate repulsively? Since the stress energy ...
- 135
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58
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Lightspeed and Mass=Gravity [duplicate]
As an object approaches the speed of light, its observed mass becomes infinitely large -- Does the Gravity of the object show a corresponding increase and become infinitely large?
- 11
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61
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How much of an observer's field of view will be black upon crossing an event horizon? [closed]
The aberration of light will cause an observer to still see a black hole as "distant" when the event horizon is crossed.
This means that if the observer looks directly toward the center of ...
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51
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Can gravitational waves be compared with a sinking water phenomena?
Let's say we have some water in the sink and open the closure. The water starts to move towards it in a whirlpool-like manner. If we have a table tennis ball and leave it near the hole of the sink it ...
- 2,255
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Calculating an arbitrary metric tensor (field) in vacuum: Make use of the constant speed of light?
The metric (=field of metric tensors) is the solution of Einstein's field equations when a special distribution of matter is given. It is among the unsolved problems of physics to calculate the metric ...
- 93
2
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76
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Newton-Cartan from GR
How does EFE reduce to Newton-Cartan Field Equation $R_{tt}=4\pi G \rho$ in Newtonian Limit? I understand its direct derivation from geodesics in weak field, what I am curious about is how EFE reduces ...
- 1,161
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Black Holes and Gravity [duplicate]
We know that nothing including light can escape the gravitational pull of black hole. Now special relativity says that nothing travels faster than speed of light. Then how can effects of gravity due ...
-2
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3
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103
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Can gravity make something faster than light? [duplicate]
Scenario,
Let's say we have complete vacuum and nothing in the universe.
If we place 2 bodies at infinite separation and have HUGE masses ($m1, m2 \sim 10^{1000}$ kg or something):
They will attract.
...
- 1
-4
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2
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103
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Speed of light affected by gravity or frame dragging effect
If we do not really 100% know how light works as a oscillation we also do not know is its speed indeed constant no matter is there a space or space-time motion that can affect it. Could a device that ...
- 2,255
-1
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3
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197
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How much mass is needed to make the speed of light equal to 1 mile per second?
The speed of light in special relativity is a constant, 186,000 miles per second, but in general relativity, "the speed of a light wave depends on the strength of the gravitational potential ...
- 29
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2
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90
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What happens when an object being accelerated by gravity begins to approach light speed? [closed]
Imagine you have a pair of 2-dimensional circular portals, with one placed perfectly above the other (practically the same as portals in the Portal games). A spherical object is held between the ...
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