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There are no stable photon orbits around black holes (see this answer). Black holes do have an unstable photon orbit though. "Unstable" here means that any tiny deviation from this orbit, will case the photon to be either scattered to infinity or sent into the black hole. It should be emphasized that there such orbits are always circular an can ...

18

The amount of "gravitational light bending" is independent of the photon energy (light wavelength). The reason is that the light follows a path through spacetime that is appropriate for a massless particle and this is unique for a given set of initial conditions. That this is so is amply demonstrated by the consistent angular displacement of "...

0

There is absolutely no way to know right now what will happen. It's my personal belief that we aren't just expanding into nothingness forever, but will have endless interactions with other universes in the mesh of existence, or maybe we will stop expanding and collapse again. We may even know that answer in our lifetime. That said, the night sky could have ...

0

Nope! The universe's expansion is accelerating, which means there's a "horizon" beyond which light can never reach us, no matter how long it travels. Although the light always travels at the speed of light, the "amount of space" between photon and us can increase faster than the speed of light. This isn't a real "speed" - it's ...

0

First, there is no "...amount of energy it takes to travel at light speed." That is the issue. The amount of energy required to approach the speed of light increases asymptotically, reaching infinity at the speed of light itself. This is the issue. There is no conventional way to accelerate mass to the speed of light threshold. That said, ...

0

The strongest argument against FTL travel-- or communication-- is that it would allow causality violations just as traveling backwards in time would. Given FTL travel and different relativistic frames of reference, you could change things in the past. And no, it doesn't mean things would just appear to go back in time; you would have frames of reference in ...

2

It’s not people who say we cannot travel at or faster than the speed of light, it’s the theoretical models that say so. Those models, in particular, general relativity, are the best theories available so far to explain everything we can observe and nothing we observe is in contradiction to those theories. In the frame of those models we must come to the ...

2

Imagine your line as a rectangle of width $w$ and depth $d$ relative to a normalised continuum. Without scattered light, the area blocked off by the line is $wd$ and if the continuum level is normalised to 1, then the equivalent width is $wd$. Now add 5% scattered light. The height of the continuum is 1.05 (but we're going to renormalise it) and the depth ...

5

Your problems with shielding your eyes from light probably come because it is easy to shield them from direct light from the car lights, but hard to shield them from reflected car light coming from every angle. I suggest that you experiment with closeing your eyelids while shining lights at your face. I just tried shutting my eyes while looking at a light ...

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