If you had a time machine…

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  • #1171

    But thanks for pointing one thing out that many scientists stress: You can’t go faster than the speed of light. I guess we’ll have to depend on wormholes then…

    anyone understand the logic behind that? if speed is relative, then how the hell can there be a limit to how fast you can go?

    #1173
    Profile photo of Cometgreen
    Cometgreen
    Member

    In those books time is treated as though history is pre-planned: any changes in history you made when you went back in time were already there in the future.

    I’m glad those books got something right. Many scientists believe that, basically, time is straight. Whatever happened in the past, happened in the past. You can’t change it. If you went back in time, killed your grandfather, and did the dirty with your grandmother, then you’re your own grandfather and always were (kudos to anyone who can pick up that reference). That’s what makes time travel to the past so confusing. If you were framed by someone, then went back in time and stopped yourself from being framed, then you were never framed, which means that you never needed to go back in time in the first place. This of course means that it wasn’t stopped, so you will be framed, and then the vicious cycle will start once again. :)

    I must applaud Buxton for making his time travel crew in OOT move forward in time, instead of backwards. I was so relieved when they said that their machine moved them forward in time. It kept me from getting analytical.

    anyone understand the logic behind that? if speed is relative, then how the hell can there be a limit to how fast you can go?

    Heh, I always found that confusing too. I guess you have to read Revmen’s post. There’s just something special with light. A friend of mine says it is possible to travel faster than light, you just have to “jump into it.” I think he may have missed something there. He said that you can’t accelerate past the speed of light, you just need to burst into the speed of light. I don’t know, he was probably just trying to act smart.

    Cometgreen, realizing he’s a nerd

    #1175
    Profile photo of Blunty
    Blunty
    Member

    what I find incrediable about this thread, with all the talk of time travel, and grandfather paradox’s… in the astounding coincidental timing of it… you’ll see what I mean when I finnish my new movie ;)

    #1176
    Profile photo of Cometgreen
    Cometgreen
    Member

    Uhoh…

    Wait, yay! New Bluntman flick!

    Cometgreen

    #1177
    Profile photo of legogod
    legogod
    Member

    At my high school, senior year, there was a talent show for five guys called “Mr. PHS.” The winner got his tuxedo for the prom paid for by the school (limo, tickets, food included). I entered and sang “I’m my own grandpa” (for the talent portion) in front of an audience of five hundred. Even though I didn’t win first, I made a big enough impression to gain second :P

    As for the relativity principle:
    It’s something everyone should ponder at least once a day when time is brought up in conversation. “Things are going too fast.” “If we hadn’t changed our clocks ahead, it would be 5 pm right now.”

    Now, a movie explains (and doesn’t explain) this principle very well. Donnie Darko is THE best film about time travel I have ever seen. I recommend it to everyone who has answered this thread, and even those who think daily about time. If you like it enough, I’d be happy to discuss it through email or PM.

    Jared

    #1178
    Profile photo of RevMen
    RevMen
    Member

    “Brian of Paco” wrote:
    anyone understand the logic behind that? if speed is relative, then how the hell can there be a limit to how fast you can go?

    It has everything to do with energy. Einstein really came and screwed everything up with his relativity theories. In Einstein’s world, energy and mass are two versions of the same thing (e=mc^2 and all that). (I’m going off of memory here, so I might get some of this stuff wrong) Mass, instead of being its own thing, becomes something called rest energy. As you speed something up, more of its rest energy becomes kinetic energy. Eventually, when you reach the speed of light, you’ve got all kinetic energy and no rest energy, and so there’s no way for it to be any faster. At least that’s how I remember it.

    People often sum up the relativity theories by saying “everything is relative” or “speed is relative.” This is very far from the truth. It is possible to have an absolute speed, which would be speed with respect to the universe. All of our usual equations for speed and acceleration are designed around the concept of choosing a point of reference, and so that’s the way we think. For the vast majority of cases, they work fine. Same with Newton’s gravity equation, for the great majority of applications, it’s fine. Problems start to arise when you deal with extreme speed or gravity. That’s where Einstein made his “adjustments.”

    The key to understanding special relativity is the speed of light. The most important concept is this: no matter where you are or how fast you’re going, light will appear to you to be traveling at 300k km/s.*

    So what if you’re in a car that’s going 200k km/s and you have your headlights on? Does the light from your headlights appear to be going 100k km/s? Nope, to the person driving the car, the light from the headlights is moving away from the car at 300k km/s.

    So what if I’m standing by the side of the road and you go zooming by me at 200k km/s, does that light appear to be going 500k km/s to me? Nope, if I’m standing by the side of the road when you go zooming by, the light from your headlights is going 300k km/s and your car is going 200k km/s. To me standing by the road, you are indeed going 2/3 the speed of the light from your headlights.

    These seemingly contradictory points of view are reconciled by
    1) A change in time, which has been discussed quite a bit here and
    2) a change in length, which is really freaky. I don’t remember enough about it to explain it clearly, I’m too lazy to go look it up, and I’m not sure anyone’s interested in reading about it here.

    *In a vacuum. Light actually moves a little slower through gases and liquids. This gives rise to a very cool phenomenon called Cherenkov radiation. It happens when subatomic particles travel through a medium at faster than the speed of light for that medium. The particles are still traveling slower than the speed of light in a vacuum. Cherenkov radiation is a very pretty blue glow that comes from whatever liquid or gas the particles are traveling through. If you’ve ever seen the blue glow from a nuclear reactor core, that is Cherenkov radiation. I have personally seen a Cherenkov glow when I looked into the core of a training reactor at the Budapest University of Technology and Economics where I was studying abroad. Yes, I looked directly at the core with no barriers of any kind blocking my view. The power from the reactor was very small, as it was only a training reactor, but radiation is radiation, and I couldn’t stay for very long. It was the truest color of blue I will probably ever see.

    Ever seen or read Starship Troopers? Their ships were powered by a “Cherenkov Drive.”

    #1179
    Profile photo of Flash1015
    Flash1015
    Member

    I don’t know, Doc Brown and Marty Mcfly make it pretty obvious that the future is more of “Random” events then a set plan, but back on the “setting the molecules to it’s exact spot and order to go back in time is pretty interesting to me” Maybe it’s possible to Isolate a chamber and then rearrange the particles in there to go back in time, Then you can brag to your friends saying you were breathing air from 2 weeks ago ;)

    also, very interesting Paradox Cometgreen maybe you should have a discussion with Phillip J. Fry from Futurama and he can tell you his grandfather story.

    #1181
    Profile photo of Cometgreen
    Cometgreen
    Member

    *gives a Kudos bar to flash* ;)

    Thanks for that more indepth explanation Revmen. I’d like to see one of those reactors too, it sounds pretty cool. At least I’ve now learned a little bit about Cherenkov radiation.

    Cometgreen

    #1182

    “legogod” wrote: Now, a movie explains (and doesn’t explain) this principle very well. Donnie Darko is THE best film about time travel I have ever seen. I recommend it to everyone who has answered this thread, and even those who think daily about time. If you like it enough, I’d be happy to discuss it through email or PM.

    Jared

    Geez, that movie is confusing :? And that bunny was scarry :-( But it was good when at the end it all came together (just to be screwed up again at the very end :o ) (NOTE: Parts of the movie aren’t really appropriate for younger kids. You’ve been warned, so dont come to us :P)

    ======================
    I just need to replace my flux capacitor, and I’m good to go!

    #1183
    Profile photo of Stefan
    Stefan
    Member

    RevMen missed a small point: depending on your definitions, Einstein’s most famous formula is not relativistically correct. It should read

    E = gamma m c^2, where gamma is 1 over the square root of 1 – gamma^2/c^2.

    That square root is what causes all trouble in the theory: as the speed approaches c, the number under it goes to 0 and consequently the energy approaches infinity. Another way to look at it is that your mass increases as you approach light speed. Accelerating further costs increasingly much energy, and reaching light speed costs an infinite amount of energy. Only particles with absolutely no mass (photons) can therefore travel at light speed. It is debatable whether wormholes will solve this problem, but new theories of physics (most notably string theory) might provide workarounds by introducing a set of new dimensions, which are curled up…

    Confused yet? Donnie Darko (which I saw only last week, and which is one great film) certainly won’t make things clearer! I was most puzzled by the man in the red suit: why does he re-appear just when the party starts?

    Oh, personally I’d travel about 20 to 30 years back and buy all these great sets at retail-prices!

    Stefan.

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