# The Naked Scientists Forum

### Author Topic: Having Trouble with Time and Space  (Read 2384 times)

#### Xin

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• Posts: 23
##### Having Trouble with Time and Space
« on: 16/11/2006 22:40:52 »
I don't understand how Time dilates when moving at extremely fast speeds and hoping someone can give me some insight. Take the Twin Paradox for example...how is it that the twin that's traveling at 60% of lightspeed ages slower than his counterpart? I'm sure I'm not thinking of it in the correct way, but wouldn't that mean that if I could travel at the speed of light that I'd never age? I'd live forever?

To me, it seems that this Paradox is assuming that Time and Space are the same. Here's the way I'm looking at this, and please help me understand if I'm wrong:

Let's suppose there's a star 5 light years away from Earth that has died and became a Supernova. Obviously, from Earth the star still appears in the nightsky and we won't see the supernova for another 5 years. If I begin traveling towards this star at the speed of light, I'll notice 2 things:

1) Time will appear to speed up as I'm looking forward, correct? This is because I'm moving headon into light from that star that is heading towards me at the speed of light...so I'll notice events happening faster. By the time I reach the light of the star turning into a supernova, I will see the supernova happening at something like 2x speed.
2) Time will appear to stop or slow down as I look behind me. This is because I'm traveling at the same speed as the light heading in the same direction. If I were to travel faster than light, then it would appear that Time is reversing, yes?

But none of this means that Time did indeed get manipulated. It's all an optical illusion.

Now, let's suppose 5 years of travel and I reach the star (now a supernova). If I look at the Earth from here, I'll be looking at an image of Earth that is 5 years old. My Twin on Earth will look exactly as he did the day I left Earth, even though he is 5 years older now. Essentially, I am looking at a representation of the past because light doesn't move instantaneously. If I were to instantaneously travel back to Earth...my Twin would be 5 years older than what I observed from the Supernova site. And I would be 5 years older than when I left Earth. But we'd still be the same age to my understanding...assuming that Time and Space are separate entities/dimensions.

So where am I wrong in all this?

#### DoctorBeaver

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##### Re: Having Trouble with Time and Space
« Reply #1 on: 17/11/2006 18:24:32 »
From his own perspective the twin travelling at 60% light speed will age normally, as will the twin who remains stationary. The reason for the disparity is that whatever speed you travel at, light will always travel 300,000kps faster. In other words, light will always appear to move away from you as if you were stationary no matter how fast you are moving. However, the actual speed of light is invariable so therefore something else must change its value to compensate, and that something else is time.

#### The Naked Scientists Forum

##### Re: Having Trouble with Time and Space
« Reply #1 on: 17/11/2006 18:24:32 »