# Tag Info

Accepted

### It takes light roughly 8 minutes to travel to Earth from the Sun, but based on which perspective?

If I interpreted this article correctly, then the answer to my question should be: 8 minutes is what we perceive, whereas for the photon the journey is instantaneous, due to the fact that it travels ...
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### It takes light roughly 8 minutes to travel to Earth from the Sun, but based on which perspective?

When people talk about the time taken for light to go from the Sun to the Earth, they're generally just considering classical Newtonian mechanics, not relativity. So we simply divide the distance by ...
• 835
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### When we see the Sun, do we actually see its past?

Yes, you are right. We don't only see the Sun 8 minutes in the past, we actually see the past of everything in space. We even see our closest companion, the Moon, 1 second in the past. The further an ...
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### How old would I be if I travelled 1000 light years in one year

The answer is sort of trivial. If you travel 1000 ly so fast that in your own reference frame it takes one year, then you will have aged by one year in your own reference frame. To do so, you will ...
• 33.8k
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### Age of the universe and time dilation

The answer is yes time dilation does affect how much time an observer experiences since the big bang until the present (cosmological) time. However there is a certain set of special observers called ...
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And that is why you don't do the calculations in a frame that is moving at lightspeed. If you have two observers that are moving relative to each other you can use the Lorentz transformation to ...
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### Age of the universe and time dilation

In the standard model, the universe looks the same for all locations moving in the local rest frame. This includes its apparent age. You can tell if you are in the local rest frame if the expansion ...
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### In theory, is there anywhere in the universe where velocity=0?

Yes. The velocities you list (X, Y, …) are all velocities with respect to some reference frame. But all reference frames are arbitrary, and you can always define a reference frame where the velocity ...
• 33.8k
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### Contradiction of special theory of relativity and quantum mechanics

There is no contradiction between special relativity and quantum mechanics. Quantum field theory fully merges special relativity and quantum mechanics to describe relativistic electrons and protons (...
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### How long would it take to reach the edge of the reachable universe?

Jonathan's answer is essentially correct, but as Rob Jeffries comments, he doesn't take into account that the Universe is expanding during the journey. The edge of the observable Universe is 47 ...
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### Can anyone one show how speeds greater than c cause a paradox on a space time diagram?

Suppose there was a magic gun that fired a bullet at ten times the speed of light relative to the firer. If I have the only such gun, and I don't move then there is no paradox. But now suppose ...
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### How does time work beyond the cosmic event horizon?

First, let's clear up a few misconceptions: The Hubble sphere The speed of light as an upper limit is valid in special relativity (SR). In general relativity (GR), which must be used to describe the ...
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### How much time passes in the outside universe when falling into a black hole?

You are essentially asking the following: if someone falls from the Earth from some way beyond the event horizon of a black hole, how long after they have left can an observer on Earth still signal to ...
• 118k
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### Observing a point 13.82b ly away, 1b years ago

Time is kind of funny when you look at such distances. Let's imagine that you are running away from a person throwing a ball at you. The ball will travel further to hit you, based on your speed, than ...
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### If an object with mass were to somehow go the speed of light, would it destroy the whole universe?

Would an object with mass traveling the speed of light destroy the whole universe because it would have infinite energy / mass? If we understand the question as a limiting process, which is the only ...
• 7,684
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### How far into the future can we go by traveling close to a black hole?

The way that you have specified the question, the answer is as far as you like. You simply put your spaceship into any orbit around the black hole and wait. A more sensible question is what is the ...
• 118k

1) In the early universe 13 billion years ago when the star first emitted the photon, there was no Hubble Telescope for the photon to instantaneously collide with from its frame of reference. In other ...
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