To infinity and beyond!?

coopertronic · Post by **coopertronic** » Thu Sep 29, 2011 10:50 pm

They are talking about raising the speed limit to 80mph/130kph in Briton. WEEEEEEEEEEEE!!!!!!!

Makida · Post by **Makida** » Fri Sep 30, 2011 12:30 pm

BackTrak wrote:QUOTE (BackTrak @ Sep 29 2011, 02:41 PM) Why does moving faster than a photon dictate time travel? What if moving faster than light just means you are going to get there quicker.

Moving at any speed is time travel, from some point of view.

That's the weird thing about relativity. If you walk past me at a normal walking speed while I'm sitting still, time is passing at a slightly different rate for you than it is for me -- just to such a tiny extent that it's not noticeable. But this fact means that if you could send information from place to place instantaneously, you could theoretically make use of time dilation to send information into your own past. It would just take a bit of planning.

(I remember there was a clever way of doing this involving three observers sending instantaneous messages to each other while moving at different speeds, which ultimately allowed one of the observers to send information to their own past -- but can't recall the details just now -- see that lengthy link I posted, it's probably in there somewhere.

) Exceeding the speed of light doesn't cause time travel. Rather, it removes a barrier our universe possesses that keeps this sort of causality-violating trickery from being possible in the first place. In other words, don't think of FTL travel as creating the possibility of time travel -- instead, think of time travel as being possible by "default," as long as relativity is true (and we know from experiments that it probably is), and the light speed limit as a "barrier" that keeps this from messing up causality.

Again, I never really understood any of this from the beginning, but that's what I remember form my attempts to read about it.

raumvogel · Post by **raumvogel** » Fri Sep 30, 2011 3:19 pm

Time is an invention of Humans.

Post by **BackTrak** » Fri Sep 30, 2011 7:57 pm

raumvogel wrote:QUOTE (raumvogel @ Sep 30 2011, 10:19 AM) Time is an invention of Humans.

Raum: The dinosaurs in the Jurassic age were always saying that to those Triassic age nooblets.

GB: Maybe I am barking up the magnet tree, but I don't get it. If I put MrC into a chimp-tin and launch him at C++ for 5 minutes, then he farts for 10 seconds, and then he returns at C++ for 5 minutes, does it not take 10 minutes and 10 seconds for him to round trip? I'm not sure where the time shift comes from. I wait 10:10, and he's folded up nicely for 10:10. When he gets back, the smell should be about the same, but my gray hair count will not have changed. Are we talking about what would be on a watch in each location (one watch in the monkey pod, and one on my arm?) From what I remember of the theory, it says that his watch should have barely moved, while mine is at 10:10. WTF?

Sure, he went far and all, but I don't see why time is moving faster/slower for anyone involved? Ugggg... I don't get it.

I guess I will have to go off and read up on it. Internetz are wonderful!

Edit:

http://www.youtube.com/watch?v=rek7881OGRY

Ok, I may just not have thought this all the way thru, but it seems to me that if you base your measurement off light, and then use the distance of light to shown a decreasing measurement, you have moved the size parameters of the clock by accelerating it. BOLLUX! The light based clock is a LIE! In fact, I don't think you could accurately measure time with any vibration based device (I'm lookin' at u, quartz!!) How about if I used an atomic clock, and measured radiation decay? I don't think you would see any time dilation at all based on the way this video explained it (based on my soft grasp of the thing). From the way I'm looking at it, special relativity points out that time measuring devices become inaccurate as C is approached, not that actual time moves about.

I proved my theory by shaking my kitchen clock really hard, and it stopped dead. BAM! SCIENCE!!

Makida · Post by **Makida** » Sat Oct 01, 2011 1:10 am

Ehhh, read that link I posted, especially section 1.3 seems to be relevant, though the stuff before it will help it make sense. I can't explain it, and I'm pretty sure I already got a lot of things wrong with what I said in this thread so far.

I need to re-read it myself.

At the end of the day, it's just the way our universe works, and trying to understand it on a purely intuitive level, without taking your time to learn the theory behind it step by step, might simply not work. The world isn't always intuitive. Like, why do big things pull small things towards themselves with gravity? Just because the Earth is really big relative to all the stuff on it, why does it somehow magically attract that stuff towards itself? It makes no intuitive sense at all! Yet, there it is. Trying to understand this stuff makes me want to either go to sleep or become a physics undergrad. Previously largely the latter, and nowadays largely the former.

SharpFish · Post by **SharpFish** » Sun Oct 02, 2011 12:25 pm

BackTrak wrote:QUOTE (BackTrak @ Sep 30 2011, 12:57 PM) Are we talking about what would be on a watch in each location (one watch in the monkey pod, and one on my arm?) From what I remember of the theory, it says that his watch should have barely moved, while mine is at 10:10. WTF?

Yes. Conveniently, at 98% of the speed of light, the time dilation factor is 2. So if the journey in your scenario was at 0.98c, you would have waited 10:10, and he would have experienced 5:10.

QUOTE Ok, I may just not have thought this all the way thru, but it seems to me that if you base your measurement off light, and then use the distance of light to shown a decreasing measurement, you have moved the size parameters of the clock by accelerating it. BOLLUX! The light based clock is a LIE! In fact, I don't think you could accurately measure time with any vibration based device (I'm lookin' at u, quartz!!) How about if I used an atomic clock, and measured radiation decay? I don't think you would see any time dilation at all based on the way this video explained it (based on my soft grasp of the thing). From the way I'm looking at it, special relativity points out that time measuring devices become inaccurate as C is approached, not that actual time moves about.[/quote]

I think there's simpler way of looking at it. Lets say I have this tube that's 300km long. Obviously light take 1 sec to reach the end. But if that tube moves at half c, 150kkps, we see differences. In this case, to an external observer, the light is emitted from one end at travels to the other at 300kps, but the far end has in the mean while moved further along; in the 1 sec that the light covers 300k km, the far end has moved 150k km away. Thus, the light does not reach the end of the tube in 1 second anymore, because it's got a total of 450k km to cover.

Except, the speed of light is the same to all observers. So if I was riding in the tube, the external motion would be invisible to me. The tube is 300k km long, and light covers it in 1 second. And thus the difference: depending on whether you are inside the tube, moving with it, or outside the tube, stationary, the same speed of light both does and does not reach the end of the tube in 1 second.

Anyway. turns out that FermiLab also detected neutrinos moving FTL a few years ago, but it was within the margin of error of their instruments so it didn't make a big splash. And indeed its likely that this will eventually turn out to all be a measurement error of some kind. I'd be very surprised if that is not the case.

Broodwich · Post by **Broodwich** » Sat Oct 15, 2011 11:25 am

http://dvice.com/archives/2011/10/speedy-neutrino.php

think we broke an alleg law of physics in the process tho

Broodwich · Post by **Broodwich** » Thu Feb 23, 2012 9:13 am

get owned
http://www.telegraph.co.uk/science/science...aulty-wire.html

Heyoka · Post by **Heyoka** » Thu Feb 23, 2012 9:33 am

Stop ruining my life, Brood!

Broodwich · Post by **Broodwich** » Thu Feb 23, 2012 10:28 am

On the contrary Heyoka, I just saved it