#1
Here's one for the physicists. I'm struggling to get my head around this one!
Ok so we know that the faster an object goes with relation to our reference frame, the shorter the time we appear to be passing on that object. So what if the object is moving at the speed of light?

By subbing the values for an object at the speed of light into the equation:
-------_________
t'=t √1-v^2/c^2

We get a value of zero for the time indicated.
Does this mean that time does not exist for an object at the speed of light? If it were possible for me to travel at the speed of light (which we all know it's not), and I was to travel to some planet hundreds of light years away, would I arrive as my normal 17 year old self?

Also. Does this equation prove that it's not possible to travel back in time due to the fact that you cannot travel faster than the speed of light? (and if you could, the equation would no longer work because it would yield a square root of a negative).

Thanks for reading.
Hope it makes sense.
Quote by lachyray
do you reckon straight edge people ever get temped to drink alcahole,
when really want to but they know they can't so they just dont?
#2
I think moving at the speed of light is not possible for anything except light, the energy required would be more than exists in the universe. At least I think that's what Richard Feynman said. If you travel close to the speed of light for a while and return to Earth you will have moved forward in time at a slower rate than the planet.
I wanna grow up to be a debaser
#3
do wha...?
Quote by SkyValley
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#4
No. If you travelled hundreds of lightyears, you would age hundreds of years. A light year is the distance light travels in a year. Therefore for every lightyear you travel, you would be aging a year.

And no, you can't travel backwards in time. You could never travel as fast as the speed of light. Your mass increases far to much to ever be able to produce the energy to get there. Think E=MCsquared
Demolition hands.... Got 'em!
#5
Yeah, you wouldn't age at all, but everything else you have ever known and loved will have died and been destroyed by the Covenant lol ... but seriously, you wouldn't age..
What the hell were you thinking?


i duno lol. tihs r liek wen i traid drawn maiself n teh t0ilit.

ROFL.

EPICPHAIL.

gess i cant dai.
#6
Quote by redhawk1029
Yeah, you wouldn't age at all, but everything else you have ever known and loved will have died and been destroyed by the Covenant lol ... but seriously, you wouldn't age..



err.. idk... who cares? you some kinda supa nurd or sumin?
What the hell were you thinking?


i duno lol. tihs r liek wen i traid drawn maiself n teh t0ilit.

ROFL.

EPICPHAIL.

gess i cant dai.
#8
Running with your results, and my understanding of time dilation...

Theoretically, if you were to travel at the speed of light, time would not affect you in relation to a 'normal' frame of reference (if, we assume, that this normality is a person here on Earth), meaning thus that you would arrive at your destination at your current age. If you were to travel back to Earth at the same speed as which your first leg of the journey, you shouldnt have aged more than the time it took for you to turn your transport device around, and accelerate back. The Earth, and everything upon it, would have aged according to their own frame of reference, but you should not have aged in any substantial manner.

This hypothesis, however, assumes that you have an engine capable of huge velocities, and can attain such speeds in a reasonably fast time. Impractical, but i dont believe such a device impossible.

Feel free to prove me wrong. I'm sure i messed up somewhere.
#9
i think you would age slower than everything else because if a clock in a plane that flies around the earth is slowed down compared to a clock which had the exact same time on it on earth before it left then sub in in the light for the plane and hey presto.
Quote by Roc8995
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#10
If light can go the speed of light, other particles must be able to as well (since light is technically not just "waves" as most people think)

The simple answer is to simply substitute V for C, therefore the fraction cancelling and the time passage being 0.
There is also another formula stating that as a particle it increases speed to the speed of light, it gains mass (its all to do with the Lorentz factor). Anyway, at the speed of light, the mass turns out to be infinite, and therefore by the laws of physics, anything with with mass gives of a gravitational field, then since the mass ins infinite, so must the gravitational field. A gravitational field that strong, would contract the universe, and you receive the same effect as stated in the distance contraction law. (ill put a link to it all at the end).

Therefore, technically, by travelling at the speed of light, you aren't actually moving, as the universe has contracted to nothing, and the time passing is nothing, and velocity is governed by v=s/t (using s to represent displacement, and t time) then v =0/0 and you get an awful mess lol

Anything divided by zero is infinity, but anything divided by itself is one, and zero divided by anything is zero. So as you can see, no one can figure out what exactly happens.

I'm only currently educated to A level standards on physics, though as of Monday I will be at uni studying it.

There are also other theories that then relate particles travelling at light speed becoming heavy enough to skip dimensions, and the theory then goes on to state that each particle that travels at the speed of light swaps dimension, and breaks down (what we call the big bang)

/end geekiness lol

click here for more info.

edit: i just remembered something, physicists in Geneva have claimed to find an annihilation process that manages to go faster than the speed of light, though nothing has been confirmed
Last edited by l3vity at Sep 13, 2007,
#11
Quote by The_Raven
It depends on how we factor e=mcsquared into the situation.

Movement at the speed of light is technically possible, in forms of exotic energy, the majority of which is currently unreachable on Earth. I do not see where speed of light truly equates with Time travel as we generally accept and know it. Of course, if a human could theoritacally run at the speed of light around the Earth, he would age as a lightyear is a year, after all and the body ages no matter what is hit at it. You would still be contained in the same Time frame as the world around you, but you would be moving mind-boggingly fast. However, that was said only for the sake of the discussion in general and human travel at the speed of light is generally accepted as impossible, and when you thinka bout it stupid-why the heck would you want to move so fast!?

Hope that answered your question but seriousley...people treat Time WAY too mathamatically these days...


Dude, if he was running at close to the speed of light around the earth he would experience time slower than the Earth. Just because he's running around it, it certainly doesn't mean he's in the same time frame as the world around him because his acceleration relative to a stationary observer on a point on the Earth's surface would be constantly changing due to his changing velocity brought about from his circular motion. Example: one atom clock at an airport synchronised with another on an airplane. Airplane flies round the earth. When it lands back at the airport the plane's clock is slightly slower than the one on the ground.

Quote by merfsullivan
No. If you travelled hundreds of lightyears, you would age hundreds of years. A light year is the distance light travels in a year. Therefore for every lightyear you travel, you would be aging a year.

And no, you can't travel backwards in time. You could never travel as fast as the speed of light. Your mass increases far to much to ever be able to produce the energy to get there. Think E=MCsquared


You're wrong on both counts: if you travelled hundreds of lightyears you would not age hundreds of years because as you approach the speed of light relative to a stationary observer, time slows for the accelerating object relative to the stationary frame. Travelling a hundred light years at close to the speed of light woudl, by definition, take (shall we say) just over a hundred years relative to the stationary point, but wouldn't take that long from the travellers point of view.

Your other point about E=mc^2 is a little off because that's only true for stationary masses. At speeds where relativity comes into play it's



because you need to take momentum into account

Quote by l3vity
If light can go the speed of light, other particles must be able to as well (since light is technically not just "waves" as most people think)

[...]

Therefore, technically, by travelling at the speed of light, you aren't actually moving, as the universe has contracted to nothing, and the time passing is nothing, and velocity is governed by v=s/t (using s to represent displacement, and t time) then v =0/0 and you get an awful mess lol

[...]

I'm only currently educated to A level standards on physics, though as of Monday I will be at uni studying it.


Your first point is a little off: EVERYTHING is a wave (electron diffraction is the most commonly quoted proof for this), electrons, protons etc; it's just that tight packets of waves act like particles

You can't use v=s/t when it comes to the speed of light because you have to factor in the Lorentz factor



and take into account both the moving and stationary frames

Where're you going to uni? I'm currently at Exeter doing physics with astrophysics: it's awesome, but pretty hard
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Last edited by Yakult at Sep 13, 2007,
#12
Quote by nz_matt


Also. Does this equation prove that it's not possible to travel back in time due to the fact that you cannot travel faster than the speed of light? (and if you could, the equation would no longer work because it would yield a square root of a negative).

Thanks for reading.
Hope it makes sense.


even when you travel at the speed of light, you still cant GO BACK in time, you can only observe the past. so instead of doing it again you would just see it.
#13
Yakult wins the thread.
What sort of job opportunities are there after uni for people studying your course?
Quote by lachyray
do you reckon straight edge people ever get temped to drink alcahole,
when really want to but they know they can't so they just dont?
#14
Quote by nz_matt
What sort of job opportunities are there after uni for people studying your course?


Anything, basically! City jobs, for example, are always looking for physicists because we're good at manipulating figures and using our heads etc.

Obviously you could also take the science route and go into research, or the teaching route and go into... erm... teaching
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#15
Research would be great but I wouldn't want to be working alone on anything for too long. I'd never want to go into teaching at a high school level. Too many people like me!

What are you hoping to do after study?
Quote by lachyray
do you reckon straight edge people ever get temped to drink alcahole,
when really want to but they know they can't so they just dont?
#16
Quote by nz_matt
Research would be great but I wouldn't want to be working alone on anything for too long. I'd never want to go into teaching at a high school level. Too many people like me!

What are you hoping to do after study?


I'm hoping to go into broadcasting actually

My dream is to work for one of the BBC radio stations (ie. Radio One or Radio Two). I know: physics has nothing to do with that, but I've got a show on my uni station so I'm getting experience and my physics degree'll just give me something to talk about in an interview situation and show (hopefully) that I'm an interesting person, haha

I'd recommend physics as a degree to anyone who's got the right kind of brain. It really changes the way you view life and makes you a lot more open minded and inquisitive.
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#17
I said technically its not just waves, never implied it wasn't waves at all lol.

and as for the end, that's what you get for not doing any work over the summer XD

I'm off to Manchester, was really impressed by there on my open day visit, I looked at many other places, Leeds was also good, was let down by Southampton, they claimed to be the best, but it was quite poor in relation to the others.
#18
Quote by l3vity
I'm off to Manchester, was really impressed by there on my open day visit, I looked at many other places, Leeds was also good, was let down by Southampton, they claimed to be the best, but it was quite poor in relation to the others.


Good call on Manchester! It's an AMAZING university, and their physics department is awesome! I was going to go there but it's a little too up north for me, and slightly too "city" if you know what I mean.

Plus you'll get to play with the Jodrell Bank observatory... Bastard
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#19
Lmao yeah, I currently live in Leeds, so I'm quite near and used to the whole living in a big city thing. The most interesting thing was seeing the research they did for the scintillation detectors for the LHC in Geneva, my interview was fun when I went for that, we got talking about physics and I ended up proving the existence of dark matter lol. Must've worked, because I got in XD

I personally plan on going into research, though I'm not totally decided on which area, I'm currently leaning towards theoretical/particles physics but nanotechnology and engineering also sound like fun. A job at Cern would be amazing tbh.
#20
Quote by The_Raven


Dude, sorry for the bluntness, but prove it. The clock would not be slower because the whole known Earth is existing in the same Time frame. Hell, there is only one Time frame! There are no differnent levels of chronological existince. As for the airplanes, a)allow for technical error! and b) how does that change the Time frame? The clocks have flown around different areas and electronic fields.

The "speedlight runner" would see everything else very slow, but only because he is moving at an impossibly quick pace. The two would be exisiting in the same Time frame, only they would apper differnent SPEEDS to each other-not different TIMES!



http://en.wikipedia.org/wiki/Hafele-Keating_experiment

proved