Thanks… I guess that’s why I am in training to be a teacher.
But it really seems to me that Mark was genuinely interested in this stuff. As for a book to read, I HIGHLY recomend a book called “The Six Roads from Newton” by an author who I believe was Edward Spenser, but I could be wrong on the author. It is by far the best layman’s explanation of advanced physics I have ever read. It covers both general and special relativity, quantum physics, probability, field theory, and the sixth one escapes me, but it is a very good book for introducing the non-mathematically inclined to some really neat physics. For the non-scientifically trained, this stuff can be confusing, since advanced physics (relativity and QM and probability physics and all that jazz) runs somewhat counter to experience, atleast somewhat counter to the aristotelian-newtonian physics that fits quite well with our experiential paradigm.
If you watch PBS or Discovery science shows, you see stuff like this thrown around all the time, but often it is either glazed over or so poorly explained that it leads to incomplete conclusions about the operation of the universe. Mark’s questions are the exact sort of stuff that people tend to ask when confronted with this stuff.
Jason R Remy
“One pill makes you taller, and one pill makes you small, but the ones that mother gives you don’t do anything at all”
– Jefferson Airplane * White Rabbit * (Slick, G. 1966)
Again, not exactly. Since velocity is the constant in our equations, rather than your velocity depending on the time and distance you travel, it works the other way around. The time and distance you travel is variable and dependant on the velocity you use to get around. Your “frame of reference,” which is defined as you and all of the stuff moving at your speed, will “age” (or advance through time) at the same rate, while everything else moving a different speed will “age” at a different rate. Thus, you don’t actually “travel into the future” when you move faster, you experience the same stuff as everyone else, you just experience it faster (if it’s in the “slower” frame of reference) or just like you weren’t moving (if it is in your frame of reference). BTW, don’t think by running down the street you can lengthen your life by increasing your time contraction (Jim Fixx proved us wrong on this one, hardy har har.) In order to witness time contraction on a level that would make a difference, you’d have to travel millions of miles per hour faster than everyone else. The phenonmenon has been witnessed on supersonic flights (~800 mph) but only on the order of nanoseconds per hour of flight time.
Jason R Remy
“One pill makes you taller, and one pill makes you small, but the ones that mother gives you don’t do anything at all”
– Jefferson Airplane * White Rabbit * (Slick, G. 1966)
Actually, time is a very real thing. You can look at time as “the rate at which things in your frame of reference do stuff” You can observe, for instance, that it takes so long for a ball to roll down an inclined plane. The units for measuring time are quite man-made, but in so far as events occur in order, and have a causal relationship (“A” must occur before “B” can) time is a real thing. At least in the macrophysical world. Particle physicists have a different idea about time and causality all together, but they’re a weird crowd anyways.
Since, before the big bang, there wasn’t anything to happen, there was also no “time” for it to occur in. Time and space are, as one way to put it, a symptom of the same property… Since there is a place to go, it takes time to get there…
Oh, and as to moving backwards through time, there is one theory that states that anti-matter (which is quite a real thing and can be observed right here on earth) is simply matter moving backwards through time. Suffice it to say that such a statement simply relies on the creative placement of a floating negative sign. I told you that particle physics crowd was a hoot.
Jason R Remy
“One pill makes you taller, and one pill makes you small, but the ones that mother gives you don’t do anything at all”
– Jefferson Airplane * White Rabbit * (Slick, G. 1966)
Mark, whenever you have a question just ask
at www.ask.com You’ll find the answer, its a pretty spiffy search engine, I use it all the time.
Let’s all try to disprove the ‘Special Theory of Relativity’:
The Special Theory has withstood the scrutiny of countless
investigators over the past ninety years and has become one
of the intellectual cornerstones of modern physics. Despite
this, it is contended that the kinematic aspects of the theory
contain a number of serious philosophical and logical
inconsistencies which effectively nullify it as a basis for
dynamic considerations.
Among these are the unsatisfactory interpretation of the first
postulate, the arbitrary limitations imposed on the means to
determine synchronism and simultaneity, and the total
exclusion of one-dimensional aspects in the justification for,
and calculation of space-time modifications.
First of all I did look on the “net” that is why I asked in the orginal question could you put a more simplified version. I had looked but only found versions that were textbooked or really so far off beat they didn’t appear to be true.
Second I thanked both the orginal two people providing me with a link and explination
Third, that ask a question link is really no better than your average search engin. I know about it.
Lastly, it is important to ask questions because you get things explained to you and if you are wrong you are shown the error of your reasoning. For a good example on my question on time travel I was told one thing by one reply, and later was advised that is essentially NOT correct. So if I had mearly gone to a link I may get one answer that agrees with my logic and never be shown it is faulty. Remember anyone can put any misinformtion or garbage on the net.
Now this brings me to this question. Could some sort of universe existed spead out, collapsed and then we have a big bang from that collapsed matter? Thus there would be a “Time” frame during that period where nothing would exist.
Well, there is no need to define time travel into the future as a teleporting leap. It could be a smooth process, just as in The Time Machine by H.G. Welles. I think it is perfectly reasonable to call the “twins paradox” effect time travel into the future.
And also, while you are travelling at high speeds relative to your friends, you actually see their actions going slower rather than faster. The net effect of you observing their events going faster happens in a sudden burst when you decelerate down from your fast speed.
This idea has often been thrown around, but it is really beyond the perview of physics to tackle that. That is more of an issue for philosophy. It is inherently impossible for us to attempt to detect such a possibility. My personal feeling is that the idea is just a natural trap of the mind-- that we find it hard to accept that there could be a beginning or end of time itself. Of course the idea that the universe might collapse is on the wane right now. Discoveries in recent years have brought the vast majority of cosmologists and astronomers to believe that the universe will expand forever.
Yeah, that is a kinda goofy, fanciful idea that largely results from the time-symmetry of most interactions. I think this idea will be killed when we gain use of anti-matter sophisticated enough to demonstrate that the entropy of anti-matter increases in the same time direction as regular matter.
Let me put forth an example that is possible within relativity, which I think fairly well matches what Markxxx is saying.
Joe and Bob are on Earth together. Joe leaves the Earth, reaching the point that he is travelling very, very close to the speed of light from Bob’s (the Earth’s) perspective. Joe continues his voyage for 6 months, and when he returns to Earth, Bob is dead because 100 years have passed on Earth.
Is this different from what Markxxx was asking? By my definition of time travel, this is time travel into the future.
Well, again it depends on whether you define time-travel as simply progressing through a frame of reference that is moving at a different rate OR actually skipping a period of time and reappearing in a future time. If you wish to define it however you feel makes it most convenient for you to convince youself it can occur, go ahead.
OK, try it this way: At speeds near the speed of light, the time of your frame of reference slows down and the distance between where you are and where you are going shrinks. The result is two fold: Nothing happens to the stuff in your frame of reference, and the rest of the world whizzes by at a much faster rate of time. If this is time travel, so be it. But you haven’t jumped through time, you’ve just moved faster than everyone else. “Travel” implies reversablity; if you can get there you can get back. So far, there is no way I know of to go “backwards” through time. The near-lightspeed “time travel” is no different than the kind of time travel we commit now, that is always forward, at a rate that is determined by the relative difference in speed between us and something else.
Jason R Remy
“One pill makes you taller, and one pill makes you small, but the ones that mother gives you don’t do anything at all”
– Jefferson Airplane * White Rabbit * (Slick, G. 1966)
Clearly this is primarily a difference in definitions of what time travel is. Few comments here tho…
Unless I am misinterpreting what you are saying, this is wrong.
While you are whizzing away from Earth at close to the speed of light, you do not see events on Earth going faster. As a matter of fact, you see them to go slower. Likewise, observers on Earth see that time for you is going slower.
Agreed here.
I’m not sure why you place this restriction on the definition of travel. It isn’t an implication I feel in the definition, and that implication doesn’t seem to be reflected in my dictionaries.
First of all, I would like to say that the idea of a wormhole is extremely speculative. It is a valid use of general relativity on paper, but no real evidence is out there to support their existence, and finding such evidence would be very difficult, as they would resemble black holes.
A black hole can be described as being like a funnel in space-time. A wormhole would be like two of these funnels connecting at the bottom, resulting in a bridge between two points in space-time.
Yes, this is a valid logical escape from causality violation. If it weren’t for this escape, we could logically say that time travel was impossible in a proof by contradiction. The only problem is that it lacks any physical explanation as to why you wouldn’t be able to commit the violation. Simply invoking predestination isn’t very scientifically convincing.
AFAIK, this idea is based on nothing more than the fertile imaginations of science fiction writers.
All things relative, it can just as easily be shown that Joe is stationary, and Bob and the Earth are travelling very, very close to the speed of light from Joe’s perspective. And when Bob and the Earth return, Bob finds Joe dead because 100 years have passed with Joe.
According to relativity, both cases are true, when clearly they cannot be. Hence, the twin paradox.
There is something inherent in the nature of acceleration that chooses preference of one case over the other. We still don’t know what it is. And the assumptions of relativity may be wrong, or incomplete.
Hi, Beeruser! I’ve been looking for the convo we had about this in old posts but I can’t find it.
There is no actual paradox. As with many paradoxes, there only seems to be a conflict on the surface. While acceleration is what makes the decision for us as to who ages and who doesn’t age as much, it isn’t a mystery. The only reason that acceleration is so special here is because acceleration is the process of changing reference frames. In relativity, it is fine to have two rates of time be in disagreement with each other in two different inertial reference frames. The disagreement only needs to be resolved if they both end up in the same reference frame. Since Joe ends up back in Bob’s reference frame, then Bob’s reference frame becomes the agreed result.
In the example above, it is not valid to say that Bob finds Joe dead, because Bob has not changed reference frames. Bob and the Earth do not accelerate in this senario. While you cannot say that one inertial reference frame is absolutely moving while another reference frame is absolutely still, you most certainly can say that a given reference frame absolutely is accelerating or absolutely is not accelerating. This came up in the recent Relativity vs. Radial Motion thread.
Thanks, Undead Dude, howcome you didn’t explain it before?
The last physics textbook I read called it a paradox, but that was ten years ago. I guess they resolved it? On second thought it may have been just pointing out how they resolved the paradox. But it did mention something inherent about acceleration that wasn’t known yet.
LOL! I guess this context made it come out better. I think last time I was more obsessed with giving a visual picture of what was going on.
It was never truly a mystery. I think the concept of the twins paradox was devised as a way to explain the potentially wild implications of relativity, and the word paradox was used because it would certainly sound like a paradox to the listener. Seems like the word paradox is used like that a lot.
