Relativity teaser.
| Author | Message |
FatHead
Posts: 1055
|
 Posted: 09:59AM Sep 30, 2011 |
|
You and a friend are having a race to Alpha Centauri, four light-years away. (It's actually closer to 4 1/4, but let's not complicate things.) Because going too fast will warp time because of relativity, at what speed should you go to get there before your friend ever could?
Alternatively, tell me where else I can post this, like USENET.
---This message was edited on 09:59AM Sep 30, 2011---
Shogi fan? Chess fan? Fan of the game Go? Like Japan? You should visit 81Dojo.com to play shogi. |
| Back to Top |
View Profile
Send PM
|
Mathgeek007 
Pi Guy
Posts: 1423
|
|
Posted: 07:53PM Sep 30, 2011 |
|
Depends on the size of the shuttle. The bigger, the slower.
Parents are supposed to "protect" their kids, but there's a real distinction between protection and unrealistically keeping children away from reality. - Life_Sucks --- One of my teasers was featured as the Teaser of the Day! :D Sept. 18 2011 :D YAY! |
| Back to Top |
View Profile
Send PM
Visit Wiki
|
FatHead
Posts: 1055
|
|
Posted: 01:11PM Oct 4, 2011 |
|
Hi, pretend this is a science-fictitious (or maybe futuristic) shuttle that can go any speed short of that of light. Practical isn't the issue here; only relativity is.
Shogi fan? Chess fan? Fan of the game Go? Like Japan? You should visit 81Dojo.com to play shogi. |
| Back to Top |
View Profile
Send PM
|
talanpoe
Me transmitte sursum, caledoni!
Posts: 97
|
|
Posted: 03:45PM Oct 6, 2011 |
|
FatHead wrote: You and a friend are having a race to Alpha Centauri, four light-years away. (It's actually closer to 4 1/4, but let's not complicate things.) Because going too fast will warp time because of relativity, at what speed should you go to get there before your friend ever could? Hi, pretend this is a science-fictitious (or maybe futuristic) shuttle that can go any speed short of that of light. Practical isn't the issue here; only relativity is. Wouldn't the stricture in red tend to dictate that you should go as close to light speed as you can get? Your clock on the space ship may be running slower (i.e., time may run more slowly for you) but you'll still get there ahead of your friend.
Lovely thing, relativity. It all depends on where you keep the clocks....
---This message was edited on 03:51PM Oct 6, 2011---
Unless life also hands you sugar and water, your lemonade is going to suck! |
| Back to Top |
View Profile
Send PM
Visit Wiki
|
FatHead
Posts: 1055
|
|
Posted: 09:32AM Oct 7, 2011 |
|
talanpoe wrote: FatHead wrote: You and a friend are having a race to Alpha Centauri, four light-years away. (It's actually closer to 4 1/4, but let's not complicate things.) Because going too fast will warp time because of relativity, at what speed should you go to get there before your friend ever could? Hi, pretend this is a science-fictitious (or maybe futuristic) shuttle that can go any speed short of that of light. Practical isn't the issue here; only relativity is. Wouldn't the stricture in red tend to dictate that you should go as close to light speed as you can get? Your clock on the space ship may be running slower (i.e., time may run more slowly for you) but you'll still get there ahead of your friend.
Lovely thing, relativity. It all depends on where you keep the clocks....
So that's where the puzzle lies. Too slow is too slow, but go too fast and time slows down for you, and thus, things speed up for everyone else, so that a really slow ship could beat you, and I'm not talking in the tortoise-and-hare sense, either. It's almost like you have to find the slowest relativistic speed, or the fastest non-relativistic speed, or something else.
Shogi fan? Chess fan? Fan of the game Go? Like Japan? You should visit 81Dojo.com to play shogi. |
| Back to Top |
View Profile
Send PM
|
talanpoe
Me transmitte sursum, caledoni!
Posts: 97
|
|
Posted: 10:27AM Oct 7, 2011 |
|
FatHead wrote: The fact is, if you travel at relativistic speeds (i.e. speeds near that of light), time distorts, not the motion of your clocks. You don't feel like everything's going in slow motion, but the same event goes by quicker for you than for others. A round trip to a nearby star may take a few years, but you'd return and a few centuries or millennia will have passed. (For example, you leave in the year 2011 and get back in the year 4011.) If you could go at light speed the whole time, the entire universe would rush on ahead of you into the future to the end of time.
So that's where the puzzle lies. Too slow is too slow, but go too fast and time slows down for you, and thus, things speed up for everyone else, so that a really slow ship could beat you, and I'm not talking in the tortoise-and-hare sense, either. It's almost like you have to find the slowest relativistic speed, or the fastest non-relativistic speed, or something else. Well, I'm not a physicist so I could clearly be mistaken; but yes, we do disagree. As I understand it, it does make a difference whether you're measuring time using a clock onboard your spaceship or a stationary one held by an objective observer.
Your original problem was to get there "before your friend ever could" which refers to an objective point in time, so the stationary observer's perception would govern. From the observer, you're travelling at speed S, so you'll get from point X to point Y in time T. From that same observer's perspective, your friend travelling at speed S' will get from point X to point Y in time T'; and if he's not travelling faster than you, he'll get there later (assuming you started first). The fact that time is distorted for you in your speedy little spaceship (and for your friend in his) doesn't affect the observer; the observer's time is constant so the objective speed is the deciding factor.
From your comments, it looks like you're trying to find out how to get there in the shortest subjective time (i.e., onboard clocks); and I agree that would be a question where the relativistic effects would come into play.
Any theoretical physicists out there?
Unless life also hands you sugar and water, your lemonade is going to suck! |
| Back to Top |
View Profile
Send PM
Visit Wiki
|
rolugomi
Posts: 391
|
|
Posted: 03:36PM Oct 7, 2011 |
|
I agree with talanpoe. The way I understand it, a slower ship would still be moving slower, and could therefore not get there faster.
You came back :) |
| Back to Top |
View Profile
Send PM
|
FreddyPharkas
Posts: 2471
|
|
Posted: 05:58AM Jan 19, 2012 |
|
I'm no physics superstar, but as I understand from long-gone school days:
The faster the ship goes, the quicker it arrives. The time dilation at just under light speed I'm thinking would make you get there and back in about 8 years if it's 4 light years away, but the rest of Earth would have moved on in time considerably. Of course, if you went slower it'd take you longer to get there and back and there would still be some time dilation to consider. I don't remember how linear or otherwise time dilation is relative to velocity, nor do I want to, but it's still faster to go as fast as possible, surely?
If it is linear (but I guess it isn't!):
Let's say at light speed it took 8 years, but Earth had moved on 80 years
At 10% of light speed it would take 80 years (10x as long) and Earth would have moved on a further 8 years, so it still takes longer.
So in conclusion, it's all relative! 
"If God did not intend for us to eat animals, then why did he make them out of meat?" John Cleese |
| Back to Top |
View Profile
Send PM
|
| |
Post from dangerouspie101 deleted on 02:17PM Jun 16, 2012.
|
 | |
|
Access Restricted
