If we are light, what would we see?
Light doesn't have eyes! Perhaps you could rephrase your question?
The whole universe in 0 time, i.e. nothing at all
Something like that, but we can only approach the speed (from a pseudo-theoretical quasi-practical point of view.). Our time would slow down to the point of vanishing with respect to the time of the rest of the universe, and, we would basically see the whole thing zoom to the end like a really fast fast-forward to the end of a movie. Then, who knows.
To see things zooming like a real fast-foward movie is still moving but it's just that it's fast. So light still experiences time.
But techwonder said, "The whole universe in 0 time, i.e. nothing at all".
If it's 0 time, does it mean that light sees a beautiful piece of art scenery but's it's still life. Nothing moves?
That's one of those things that I don't believe we humans are privelaged to know (at least, not for a long time). I would assume that there would be no picture at all; nothing. As if existence itself didn't even exist. But that is just based on a narrow-minded model that assumes there is nothing beyond. I am pretty sure that there would be no still-frame picture to look at. Quite the opposite. That was my reason for the limiting consideration. Just imagine the fast forward being cranked up to infinity. How long would it take to watch the movie? Would the picture look still? Would you even know you had watched a movie? What happens after the movie is over?
If we (or any other objects with mass) were ever able to travel at the speed of light, it would mean that the special theory of relativity was wrong, and a new theory would have to be found to explain why light speed for objects with mass IS possible. That theory might very well say what it would be like to go that fast.
But SR says we can't go that fast, and when a theory in physics says something is impossible, that theory has zero to say about what the thing would be like if it WERE possible!
We have mass therefore it would require infinte energy to go c...
Perhaps if you were to say you could see at c... although it really wouldn't be possible as i mentioned before the second you reach c the universe freezes, from Einsteins discription of speed you have taken all of your "velocity" out of the time dimension and are using it in the other 3 dimensions. Therefore the second you reach c you would have a snapshot of the universe, however if you were to ever decrease ur speed it would start to move again. however this is unrealistic that you could go c to being with (again see previous post), in the same aspect you could ask if were WERE able to go faster than c would we see the universe in reverse ie travel through time.
Of course you would be able to see when travelling at light speed! There are no textbook answers because such a situation is impossible since we would require infinite energy to be accelerated to such speeds. But since objects emit/reflect photons constantly, we would observe lorentz distance contraction in the extreme from stationary objects. Of course, if something was moving into our path, we wouldn't see it and would hence collide with it before it could be seen, such is the nature of light speed.
Hypothetically, if you could see anything while travelling at c, the Universe would spatially appear 2-dimensional. All lengths parallel to the direction of your velocity would be reduced to 0, hence only the dimension perpendicular to the directional vector your velocity would exist. This is also how light can get away with us observing time to stand still for it. We say it travels from point A to point B and doesn't "age" while travelling between them (stretch your mind a little, I suppose a hypothetical [and impossible] object travelling at c would illustrate this better) while from the light's perspective, it doesn't age simply because it doesn't have to go anywhere- there is no distance at all between points A and B. That's the best answer I can give: according to the Lorentz transformations, from light's perspective the universe is 2-D.
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