# Time Diallation for Dummies

1. Oct 12, 2012

### Waxb18

Hello all...

I am by no means a physicist and neither are my colleagues, however at time we find ourselves discussing the the most bizzare subjects ranging from do we really exist to would it one day be possible to upload out conciousness to a computer and live eternally.

Todays subject is travelling at the speed of light and we're all stumped...

As you may or may not have heard scientists have discovered a planet 40 light years away made from diamonds

http://uk.news.yahoo.com/astronomers-diamond-planet-180659708.html [Broken]

the Question we have, is if we travelled at the speed of light in a straight line to get to this planet, loaded up a pocketful of diamonds and travelled back in a straight line,

How long would have passed on earth?
and how long would have passed on our ship?

Last edited by a moderator: May 6, 2017
2. Oct 12, 2012

### ghwellsjr

Since the planet is 40 light years away, it would take light 40 years to get there and another 40 years to get back for a total of 80 years.

However, you cannot travel at the speed of light so the answer for you is that it would take you just over 80 years to make the round trip so if you leave now you could get back by the end of 2092. The good news is that you won't age hardly at all during the trip although who knows what this world will be like in 2092, maybe a pocketful of diamonds will be worthless.

Last edited by a moderator: May 6, 2017
3. Oct 12, 2012

### Waxb18

right...ill get packing my bags

4. Oct 12, 2012

### ghwellsjr

Better pack a jack hammer. It sounds like the diamonds there might be too big to fit into your pocket.

5. Oct 12, 2012

### ghwellsjr

Also, be forewarned, at the temperature of the planet, all the carbon in your body might just be turned into diamond when you get there.

6. Oct 12, 2012

### Muphrid

A photon travels at the speed of light. Anything traveling at the speed of light doesn't really experience the passage of time, even though it moves through space and time.

That also means it's not a realistic thing to ask about going to another planet at the speed of light. It's not just impractical--the theory makes it impossible. You can get close to the speed of light, and the time it takes will depend on just how close you get. I wasn't able to find any references on this specific problem, but doing some napkin math, here's a basic idea regarding the result I get:

Example: you travel to the diamond planet at 99.9% of the speed of light. According to Earth, the time it takes you is 40 years / .999 = about 40 years and 15 days. However, according to you, the time it takes you to travel this time is about 1 year and 9.5 months.

7. Oct 12, 2012

### Waxb18

Sorry but i never got the opportunity to study napkin math...

Can you explain where you get 1 year 9.5 months from?

8. Oct 12, 2012

### Muphrid

You take the time it would take according to Earth and divide out a factor called $\gamma=(1-.999^2)^{-1/2} \approx 22$ or so. Can't remember the exact value off the top of my head. This gamma factor shows up a lot in relativity.

9. Oct 12, 2012

### nitsuj

lol,

I foresee a superhero...

Note this service is available on Earth now. No longer just an urn of ashes, now you can get a diamond.

now I am wondering how many karats I would be.

10. Oct 12, 2012

### nitsuj

Have we ever seen light move through space?

11. Oct 12, 2012

### Muphrid

Not sure what you're asking. Light has a speed, so yes, it moves through space. Since I'm not sure what you mean, what makes you uncertain?

12. Oct 12, 2012

### nitsuj

ohh through space... not in space.