# The Real Theory of the Time Machine

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Thread starter 5 years ago
#1
It's known that we see the objects because light reflects on it and comes to our eyes. But if traveled with a velocity greater than the velocity of light, will we be able to see the reflected lights of the things present in years ago?
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5 years ago
#2
(Original post by Omer Ibrahim)
It's known that we see the objects because light reflects on it and comes to our eyes. But if traveled with a velocity greater than the velocity of light, will we be able to see the reflected lights of the things present in years ago?
Theoretically, yes. If you could outrun light, you could look back in to the past.
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Thread starter 5 years ago
#3
(Original post by mikeyd85)
Theoretically, yes. If you could outrun light, you could look back in to the past.
But i really can't help doubting if we can do it practically.
i believe that if a vehicle was made with an engine working by a nuclear explosion it can outrun light
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5 years ago
#4
(Original post by Omer Ibrahim)
But i really can't help doubting if we can do it practically.
i believe that if a vehicle was made with an engine working by a nuclear explosion it can outrun light
No, it couldn't. Because of relativistic effects, as your speed approaches the speed of light, the energy required to accelerate approaches infinity. You would need infinite energy to accelerate an object to the speed of light using any conventional means of acceleration, including the nuclear explosion method used by the Orion project which I assume you're referring to.

Faster than light travel isn't forbidden by the currently accepted laws of physics, but accelerating past the speed of light is.
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5 years ago
#5
We can already see into the past. Just look into the night sky. Most of what you see is light from millenia ago and what you see is not what is actually there at this present time.
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Thread starter 5 years ago
#6
(Original post by james1211)
We can already see into the past. Just look into the night sky. Most of what you see is light from millenia ago and what you see is not what is actually there at this present time.
The best way to make things clear is to draw a diagram. We'll plot some graphs of position vs. time for some photons and spaceships. We'll have time going up the vertical axis and position along the horizontal axis. Here's an example:

I've chosen units so that one second on the vertical axis is drawn the same size as one light-second on the horizontal axis. The net result is that photons always travel at 45 degree angles to the axes. Massive objects, that travel slower than light, are confined to travel on courses that have angles of smaller than 45 degrees with respect to the vertical axis. The path of the photon is the diagonal black line and the path of a spaceship is in red. It starts to the right of the photon but as we move up the time axis the photon eventually catches up with it.

If the spaceship travels faster then it will follow an angle closer to 45 degrees. Here are a pair of paths corresponding to faster spaceships:

The faster the ship is, the further it gets before the photon catches up. But we're just putting off the inevitable. It seems that whatever we do, the photon will always catch up.

But there's a hidden assumption in the above. By drawing straight lines for the spaceship I was assuming it was travelling at a constant velocity. But there's no reason for that to be true. Here's a different path the spaceship could follow:

At no point does the red path of the spaceship meet the black path of the photon. And yet at no point does the red path reach 45 degrees to the vertical axis. In other words, the spaceship never travels at the speed of light, and yet the photon never catches up with it. Spaceships can outrun photons!

So what kind of path is that? It's actually a hyperbola and it corresponds to a spaceship accelerating at a constant rate. You might wonder how it can be constant acceleration when the speed of the spaceship never exceeds that of light. From an external observer's point of view, after a while it does look like the ship is travelling at a more or less constant velocity close to the speed of light. But from the point of view of someone on the spaceship it feels exactly like constant acceleration. So that is the path that would be taken by a spaceship with its thrusters firing at a constant rate
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Thread starter 5 years ago
#7
(Original post by james1211)
We can already see into the past. Just look into the night sky. Most of what you see is light from millenia ago and what you see is not what is actually there at this present time.
I know. What i mean is to see the human's evolution by the outrunning light.
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5 years ago
#8
If i could go back in time, i would **** your mum.
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5 years ago
#9
(Original post by Omer Ibrahim)
It's known that we see the objects because light reflects on it and comes to our eyes. But if traveled with a velocity greater than the velocity of light, will we be able to see the reflected lights of the things present in years ago?

If i could go back in time, i would **** your mum.
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Thread starter 5 years ago
#10
(Original post by SexieBoi123)
If i could go back in time, i would **** your mum.
I won't reply to you because it's considered as madness to try to speak to non-humans. I called a non-human because you don't use your brain just like animals or may be worst. I'm really sorry for you.
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5 years ago
#11
Wait, if you traveled faster than light does that mean you could see all the way around your head?

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