beansbaxter
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posted November 08, 2004 04:52 PM
Physics Part 9 - A real time machine...
OK lets discuss time travel, and the possibilites of time machines.
Speed+Time=The Speed of Light
No matter what the first 2 are, they MUST equal the speed of light. It has been proven that as something moves with greater velocity, the time relative to it slows down. So in theory, time would eventually have to be negative if the speed was great enough.
The speed of light is roughly 186,000 Miles per second.
As your speed increases, time slows down, correct?
Acording to this law, if you were at the speed of light,
time would = 0, as 186,000mps + 0 = 186,000mps(speed of light).
So if you could get to the speed of light, you could stop time.(relative to you at least)
But what if, you could go even further beyond that speed. Time would have to equal a negative number(going back in time) to equal the speed of light. Lets say 200,000mps+(-14,000)=186,000. You would be going back in time correct?
If this is possible, we would need an immense amount of power, and a way to keep a human being alive while going so fast, but if we passed these limitations, acording to the math above, is time travel possible?
   
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frEEk
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ummm... yeah
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posted November 09, 2004 12:50 AM
first of all, isn't the speed of light supposed to me a maximum theoretical speed for anything? besides, i'd equat the slowing down of (relative) time to the calming of particles as temp approaches 0 Kelvin. u can't have particles more slow than not moving right? at that point u'r at 0. so u can theorize all u want about how particles would gain negative movement as the temp dipped below 0, but that can never happen. besides, even if we said the subject WOULD experience a reversal of time, it wouldnt be what we generally think of as time travel, like what we see in movies. the subject may go back in time but it's still in a different position from in the past as it continues to travel where it's going right? so it's not like u could go back and relive your life or make different decisions. you could maybe get back to earth X years younger if your trip was circular but u'd have lost all your memories too, so what's the point? basically, it would be pretty useless. i guess if u just want to extend ur life by 10years it would be good for that, but how many people would trade their memories for another 10 years? wouldnt that be like throwing those 10 years away anyway? i guess if u had a really bad 10 years... Anyway, that's all dependant on teh idea that reversing time (a better term than "time travel" or "going back in time") is possible to begin with, which i find unlikely.
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slug
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posted November 09, 2004 03:18 AM
the other problem with that is our measure of time is just that, a measurement of a physical property...you could no more reverse time than you could put the cork back in the bottle of the Hiroshima bomb......
even as 'time' expands for people moving quickly, it still goes along at the same rate for everything else. just accelerating that item faster than speed of light won't do squat for the rest of everything.
the time "reversal" would only happen for that one person,a nd it would be their perception....not reality.
and really, once they got up to that speed, where time slowed down for them, time is flying so fast elsewhere that they would not know anyone or anything when and if they ever returned anyway....
but that return time would not be *before* they left, it would be a great deal of time AFTERWARDS
  
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swft
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posted November 09, 2004 05:42 AM
'zactly so!
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Spyral
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posted November 09, 2004 05:57 AM
Did you go trolling on the MENSA boards?
Now, before you get all excited Harry, I said MENSA, not NAMBLA.
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Now, I am become Death, the destroyer of worlds.
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slug
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posted November 09, 2004 01:28 PM
this is a MENSA board?!?!?!?!?
hrmm *I* surely don't belong here then not nearly as enamoured with my IQ as needed to belong to THAT club....
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DaGoose
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posted November 09, 2004 03:48 PM
Look up light cones for some interesting reading on time travel.
Also, your mass increase when velocity increases, so more than likely you would collapse into a singularity before breaking the speed of light.
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Ozzy
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posted November 09, 2004 06:26 PM
I think I would wear a seatbelt :grin
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deathpulse
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posted November 10, 2004 11:47 PM
OK wait a minute  . Let me interject some thoughts. First, if you travel fast enough, time appears to stop RELATIVE TO AN OBSERVER WHO IS GOING MUCH SLOWER THAN YOU - not to you. To you, time is constant. Now, the speed of light is approx 186,282 miles/sec IN A VACUM. Light actually slows down in other mediums (observable as "bending" objects in water etc) and has been almost slowed to a stop in recent lab experiments. Point here - light is a variable speed, but is constant as the "galactic speed limit" ONLY in a vacum. Now, as you alluded to, the faster you go, the slower time will appear relative to an observer. The problem in your thought experiement, is that that is NOT the only thing that happens. More important to the idea of moving faster than light is that your mass also increases at an exponential rate as you approach the speef of light, to the point that moving AT the speed of light (or in the instant just before you hit that speed) your mass would be close to infinate. Why is that important you ask? Well, the amount of power necessary to drive you up to those velocities would exceed the available resources. There is much more to discuss on the subject - but I'm tiured .
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Spyral
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posted November 11, 2004 05:57 AM
2 questions:
1- can I use your time machine this weekend.
2- is it safe to go back in time and mess with Harry when he was a pimply, round faced teenager?
____________
Now, I am become Death, the destroyer of worlds.
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Bagster
Zone Head
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posted November 11, 2004 06:56 AM
So when you go lightspeed you are relatively at "0" timespeed.
Does this mean that Light IS Time? :-\
Why light, Why not some invisible radiation frequencies?
Who wants to go back and watch the Andy Griffith show before it was reruns anyhow? :-)
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deathpulse
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posted November 11, 2004 09:51 AM
No Bag, light does not equal time. Time is something of speculation actually . There are some "theories" (dubious at best) that sound cool in sci-fi books etc but most of them rely on areas of undefined stuff. For instance - some people put forth the theory that a worm-hole (black hole with an entrance and an exit) can help you move "Back in time". There are many problems with this assertion, but let me drive a truck through the BIGGEST hole in the theory (and many theories like this). We are functional beings composed of matter that exists within the realm of our spacial point of reference. In other words, we exist as entities in common (to us) space-time (which some describe as a "continuum" = kind of a "human" centric way to look at it). Anyway, once we attempt to move ourselves into an area where our spacial point of reference is not compatible with our existing point of reference (IE in a black hole) there is a LARGE possability that you (as an entitiy) will cease to exist in a fashion that is conducive to vital elements of our surviaval. Many believe infact that objects are changed into different states within a black hole - like possibly pure energy. Now, there is the problem. For one of us to survive a trip "through" a black hole, we would have to survive (in a mannor that supports our fragile form of life) this type of transformation - HIGHLY unlikely. I'm NOT suggesting its impossible, but almost all nutcases or speculative physics buffs that suggest this as a viable means of transportation or time travel gloss over these "SMALL" details .
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deathpulse
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posted November 11, 2004 03:18 PM
BTW - if time travel WERE possible, wouldn't we see more peeps from the future walking around?
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beansbaxter
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posted November 11, 2004 08:44 PM
 Edited By: beansbaxter on 11 Nov 2004 20:46
While the following might someday not be true, according to what I have read the speed of light in a vacuum is a universal constant. The reason photons can go the speed of light is due their very nature.
They only exist to mediate electromagnetic radiation and only exist at the velocity of light. They do not exist at rest and have no rest mass. They only have a mass due to mass energy equivalence. (E=mc²). When an object other than a photon is accelerated it undergoes relativistic transformations with respect to other obects relative to it. The properties that undergo transformation are length (distance), time and momentum. For time and length the transformation diminishes the observed time and length for an observer who is not undergoing relativistic transformations themselves. For momentum you gain relative to an observer. Therefore at just a very tiny portion below the speed of light you have nearly an infinite momentum. In order to achieve the speed of light you would need an infinite force to accelerate the object to the speed of light. Since no infinite force exists, you will not reach the speed of light. The 3 forms of the Lorentz transformation are as follows:
Time - T(observer) = T(object) * sqrt(1 - (v²/c²))
Length - L(observer) = L(object) * sqrt(1 - (v²/c²))
Momentum - p(observer) = p(object) / sqrt(1 - (v²/c²))
Momentum - p = mv (mass * velocity)
Kinetic Energy - k = 1/2 * m * v²
As an object increases it velocity it gains an increase in kinetic energy and since energy is interchangeable
with mass the mass or total energy of the object increases.
An interesting fact appears for a photon if you apply the relativisitc transformations to a photon. The photon is already travelling at c. So therefore the time and length a photon experiences is always zero. So a photon always travels 0 distance in 0 time. Obviously this is not practically true since even light takes time to travel.
Remember to take into account the theorys of relativity.
Hopefully this explains why time travel by going faster than the speed of light is fundamentally flawed.
Almost forgot to mention: Even at small speeds we are undergoing relativistic transformations, they are just too small to observe. True relativistic effects do not start to manifest themselves until at least 10% of the speed of light.
Also for the person going relativistic speeds you do not observe any changes in your surroundiongs or in the passage of time. The reason is that all measuring devices that you are using are relative to you and are therefore undergoing transformation just as you are and remain accurate for your frame of reference.
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deathpulse
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posted November 11, 2004 08:48 PM
There ya go Beans - the more math oriented answers that I gave . At least the idea makes some GREAT sci-fi though! I STILL love the original stargate movie .
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oldkawboy
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posted November 12, 2004 04:51 AM
I believe the faster you go, the younger you feel....That's why we ride 12's, right?
When I run at Maxton, I feel like a kid again! Just look what it does to Vincent and he's 60....in earth years.
Good subject guys, I've always enjoyed dreaming about time travel.
Dan
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Spyral
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posted November 12, 2004 05:25 AM
Edited By: Spyral on 12 Nov 2004 05:27
johntitor.com
this ought to explain it all to you guys.
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Now, I am become Death, the destroyer of worlds.
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frEEk
Administrator
ummm... yeah
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posted November 12, 2004 09:53 AM
oh my poor assaulted sanity. some people have got WAY too much idle time  the original "john titor" must be laughin his ass off that people buy into his little play.
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aliveagain
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posted November 12, 2004 01:56 PM
how long would it take to slow down from light speed and would the stock brakes be sufficient.
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I wondered why the baseball kept getting bigger. Then it hit me.
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ZXLNT
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posted November 14, 2004 01:45 AM
Heck if you want to look back in time just go outside at night and look up at the stars. Some are far enough away that the like took hundreds of thousands of years to get here. You seeing them as they were hundreds of thousands of years ago, not as they are now. Interesting if you think about. Really anytime you look at something your seeing not as it is, but as it was. The farther something is away the farther back into the past your seeing..
My 2 pennies worth.
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ninja rider
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posted November 16, 2004 01:58 AM
time travel
Going back in time is not possible, at least not in the dimension we are in. Think about this: if it were possible our world would be visited by tourists from the future....... which is not (Stephen Hawking).
There is another possibility however. If universe consists of an unlimited number of parallel universes or dimensions (there are indications which seem to prove this) then, theoretically, time travel would be possible albeit not backwards into our own universe or dimension. One would only have to find a way to get into these other parallel unverses.
Ninja Rider
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Don't lie, cheat or steal, the government doesn't want any competition
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Ozzy
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posted November 16, 2004 07:28 AM
what does this have to do with how long it takes to change the spark plugs in a 12R?
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jonwright
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posted November 16, 2004 07:36 AM
To steal something from Steven Wright:
Would your headlights work?
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ddpete3
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posted November 18, 2004 07:55 AM
quote:
Heck if you want to look back in time just go outside at night and look up at the stars. Some are far enough away that the like took hundreds of thousands of years to get here. You seeing them as they were hundreds of thousands of years ago, not as they are now. Interesting if you think about. Really anytime you look at something your seeing not as it is, but as it was. The farther something is away the farther back into the past your seeing..
My 2 pennies worth.
on this note...if you were to go faster than light speed, you could show up at one of those stars at it's "now" time, then coome back here and look at it and say that you were just there a couple of hundred thousand years ago.
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Widowmaker
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posted November 18, 2004 01:05 PM
Faster than light ,DUH it's (( warp speed))
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