No. A reference frame is “constructed” using (idealized) clocks and (idealized) rigid rods. A check of your watch will tell you which frame is a valid one.
The contraction does not affect all spacial dimensions; it is only in the direction of travel.
I think that your view is biased by what the ‘Heart of Gold’ does in ‘Hitchhikers Guide to the Galaxy.’ Yes the Universe would appear to shrink to a point IMO, just like the earth would at first and then followed by the sun and then milky-way. It would seem that the vessel would be traveling from earth at the speed of light from a third party view. The person(s) on board would in effect be frozen in time and would take them an eternity just to even have a heartbeat, let alone cut the engines. The ship would become the object farthest from the center eventually and still no time would pass for said vessel. It would take an infinite amount of time (i.e. eternity) to halt course, leaving the ship at an infinite distance from its starting point. However, this vessel might be in all places at once in the universe like you said because it would achieve infinite mass at that speed and suck in everything like a monstrous blackhole. I left out the aspect of mass from the equation to make my ship work by the way.
I realize that all of this doesn’t relate to the price of cheese in Canada. I’m just quite bull-headed in my view on relativity 
Infinite improbability has nothing to do with this as interesting as a trip aboard ‘Heart of Gold’ might be. Completely different principle as they don’t accelerate to light speed at all but use Brownian Motion from a really hot cup of tea to achieve their effect.
I forgot the Universe would not contract to a point but an infinitely thin line at light speed. The Universe would have effectively zero distance in front of and behind you (if those terms even still hold relevance) but would extend ‘up’ and ‘down’ from you a very long way.
Also realize the Universe is not believed to be infinite. It is believed to be finite but unbounded. Imagine the earth is a smooth sphere. You could walk around it forever without coming to an edge or wall but it is still finite in size. I believe the same goes for the Universe as near as we can tell today.
For an interesting take on relativistic effects check out this bit on the ‘Oh-My-God Particle’.
I was thinking about this over dinner and i see what would happen with the mass and such. The mass equations would have to be ignored for the sake of an infinitely fast ship. I think that the universe could be round but it would be infinitely round if it were. the radius would obviously be infinite as well. This would leave the overall ‘‘curvature’’ of space itself nominally flat (even fractally flat) Maybe the ship would circle the universe for eternity instead of continue on into nothingness. Either way, the ship’s passenger(s) would find that eternity has passed as soon as it’s course was halted, assuming it wasn’t destroyed with the passing of existence. All of this is a speculation on the impossible, of course. I rescind the remark about the ‘heart of gold’ Whack-A-Mole . 
ok, what about this one: say 2 ships start out back to back. They accelerate in opposite directions. When both of them are travelling at .5C, would one ship see the other as travelling at the speed of light away from it? What would a third party observer at the starting point see? What about when both ships are travelling at C (or at least .99999999C)?
To each other, the ships would be traveling at a rate < infinity still so there wouldn’t be a break in the law of physics there. For a third party observer in the middle, there would be two separate extreme redshifts… I think. You can find more information on the theoretical effects of simutaneous travelers at the following link.
http://www.cco.caltech.edu/~alex/Explanations/TheTwinsParadox.htm
On earth to objects moving away from each other can simply add their velocities to get a closure or separation rate. I.e. two cars approaching one another at 50 MPH could be viewed from one car as if it were standing still and the other car was approaching at 100 MPH in terms of closure rate.
However, when you get to relativistic velocities they don’t simply add together anymore. Two spacecraft each travelling at .9c towards each other will not be able to add their velocities such that one could say it was standing still and the other was approaching at 1.8c. I think there is an equation that handles this sort of thing but I do not know it. Suffice it to say the answer will always work out to be something less than 1.0c.
Jeff41:
Part of what you are touching on relates to frames of reference. Try this on for a mind bender.
Imagine you are aboard a spaceship in an otherwise featureless Universe (i.e. void only…no planets, no stars, etc…this isn’t strictly necessary for what I’m about to talk about but it helps with the visualization). The only other thing in this void is another spaceship approaching you at, say, 500 MPH (this will work for any velocity you care to pick).
There is absolutely NO WAY for you to decide if you are standing still and the other guy is coming at you at 500 MPH or vice versa or any combination that adds up to 500 MPH (i.e. you are both moving at 250 MPH). As a result any one you pick is a CORRECT answer. Indeed, you could say you were standing still and the other guy was approaching at 500 MPH and he could decide he was standing still and you are the one who is moving and you’d both be right (sort of…you can’t both be right at the same time but nothing you or he can do could settle the problem either so you are both free to choose and from YOUR perspective you are 100% correct). Even talking to the other guy won’t help. Even if you are at relativistic speeds with time dilation and all that other good stuff that comes at those speed you still won’t be able to figure it out.
That’s a quick and dirty lesson on frames of reference.
so, if the two are going away from each other at exactly .5C, then they are just never able to detect one another, and instantaneously disappear to each other when that velocity is reached?
I just took a physics test on relativity today, so I understand frames of reference pretty well, and can calculate time dilation and length contraction, but was curious about some of the stuff my book doesn’t talk about.
The formula for adding velocities u and v is:
(u + v) / (1 + uv/c[sup]2[/sup])
For u = v = .5c, this reduces to .8c.
This formula guarantees that the relative velocity of any inertial frame as measured by any other reference frame is always less than c. Another extreme example: If u= v = 0.9c, the formula for the addition gives (1.8/1.81)c or approx 0.994475c. Sitll less than c.
Damn, got beaten to it. I was going to redeem my feeble physics performance here by deriving that formula, and I couldn’t figure out how to do it… sigh.
For starters, I’ve got some nits to pick with some of the early posts in this thread (dammit, why didn’t I see this thread earlier?). First of all, the recent neutrino results do, in fact, have interesting implications, but they’re have nothing to do with extra dimensions, microscopic black holes, or time travel. Secondly, the method of “skim close to a black hole” is not random, and cannot be used to go back in time. You can go forward in time this way (so you could, for instance, see the 500th anniversary of the signing of the Declaration of Independence), but you couldn’t go back to the signing itself. If you actually go into a sufficiently large black hole, you can get to any time you like, but that’s small consolation to you, since you’re not going to be able to get back out, and are going to be squished in short order.
Meanwhile, faster than light propagation of information is exactly as possible (or impossible) as propagation of information backwards in time. In fact, the reason most physicists consider FTL impossible is because they’re assuming, a priori, that it’s impossible to send information back in time. They usually assume this, in turn, because of the various paradoces which arise when you have time travel. So it’s a bit roundabout to say that time travel is impossible because FTL travel is impossible.
This applies, by the way, to any method for getting from Point A to Point B before light can get there. Warp drive or hyperspace or wormholes or the like might conceivable get around the energy problem, but if any of those things exist, they can still be used to build a time machine.
You’d expect, given your handle, that this would be the ideal thread for you to be monkeying around in, Chronos. From my point of view, it’s tantalizing enough a topic to speculate on ways to attempt an end-run around the limitations we’re running up against rather than simply accept them…
…however, such attempts should at least be in some way not contradicting the known things we’ve found about the universe given the same conditions used to find out the things we’ve found about the universe.
My most recent bit of favourite wish-it-could-work is the Alcubierre Warp-Drive. One might claim it can’t work precisely because of the sending-information-back-in-time problem of going faster than light, and therefore the exotic matter or technology necessary to implement it is likewise impossible, but I have to appreciate the fact that it doesn’t locally exceed the speed of light (in fact, the craft in the ‘warp’ doesn’t even move)…
Oh well, I like to dream and speculate, but I’m enough of a ‘scientist’ to require either sound theoretical justification or a working model (read: experimental evidence) or both.
This is the part I never get.
Pretend I have a Dimension Gate (never mind how it works). It’d be like a door. One side is here on earth and the other side is 10 light years away on some other planet. I can simply walk through the door as I would any door and be on this other planet.
In essence, my dimension door as shrunk the space between two points.
Where is my time machine? A photon of light can travel through the door or it can take the longer, ten year route to get to the same place. It’d be like trying to move a foot to your right. You could move the one foot to the right in about a second or you could go approximately 24,000 miles to the left and arrive at the same spot some days, weeks or months from now.
How am I doing something different here such that I would be effectively travelling in time in a time machine fashion if I used my Dimension Door?
Oh yeah Chronos:
Earlier in this thread someone wanted a cite that if you are going faster than the speed of light (say you’re a tachyon) that you could never go slower than the speed of light. Sort of the reverse of us trying to go faster than light speed. Unfortunately I haven’t found a cite talking about this but I suspect you could settle it one way or the other if you’re game.
Uh, seems reasonable – the equations governing time-dilation and ‘inertial mass’ as you approach the speed of light blow up just as easily approaching the speed of light from above it as from below it.
m = m0 / sqrt(1-v^2/c^2)
When v approaches c, the whole denominator approaches 0.
(inertial mass 0, rest mass m0)
OK. An event is a point in space at a moment in time. Your stepping into you dimension door is Event E1. Your arrival is Event E2. Let’s say that E1 and E2 occur at the same time and are 10 light years apart relative to the reference frame that contains your Dimension doors. Simultaneity is relative. There is a (moving) reference frame where E2 occurs before E1. If you have another set of Dimension Doors in this moving frame, you could step into the second set of doors and arrive in the same place as E1 before E1. There is your time machine.
I have no doubt what you say is true. You, Chronos and a few others have been pretty clear on this point in the past and you all easily surpass me in your knowledge of this stuff.
That said I still don’t get it. If you’d care to try to explain further, as you might to an 8 year old, I’d appreciate it but I wouldn’t blame you if you figure it’s just not worth the effort to hammer this info through my thick skull.
I’ll try and surmise what you said as I understand it:
Dimension Door 1 is here on earth. Dimension Door 2 is on a spaceship tolling about at relativistic speeds (say .99c). From my standpoint here on earth time is moving at a crawl aboard the spaceship compared to me. I step aboard through Door 1 and end up on the spaceship. Hang about the spaceship for (say) an hour and return back to earth through the Door 2 aboard the spaceship. However, rather than just an hour passing I find that a year (or whatever…just a guess for illustration) has passed. To me it would seem that I had jumped a year ahead in time in just one hour (from my perspective).
Still, time is moving forward for all parties. No backwards time travel that I can see such that an effect could precede a cause (E2 before E1).
What I said does not assume that one of the doors is moving relative to the other. Let’s have Door 1 and Door 2 each stationary relative to the other and 10 light years apart. Halfway between the two doors and 5 years ago, let’s imagine a light was turned on. The light reaches Door 1 as you enter it (E1). When you emerge at Door 2 (E2), you will see the light signal just reaching Door 2, because light travels at a constant speed and the distance from the source to D1 is the same as the distance to D2. Now, let’s imagine a rocket traveling from D1 to D2 at a constant speed so that we have a second inertial frame. From the point of view of this frame, D2 is moving toward the light source and D1 is moving away. The light must travel further (relative to this frame) to reach D1 than to reach D2. Now since the speed of light is constant in every inertial frame, E2 (the light arriving at D2 and coincidentally your exit) happens before E1 (the light arriving at D1 and your entrance). If we have a second pair of Dimension doors attached to this frame, we could go from E2 back to the location D1 before E1.