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Subject: Slip strem leave room for time travel?

okay i got half of that, can you simplify please... hate to sound dumb but physics is something i just dont get.
What is frame of reference? is this like "In this hypothetical situation" or something like that?

[Edited on 12.08.2010 8:38 PM PST]

  • 12.08.2010 8:36 PM PDT


Posted by: LoneRanger 521
What is frame of reference? is this like "In this hypothetical situation" or something like that?

Suppose that you're sitting in a chair on the side of a long, straight road, and you see a red car go by at 10m/s. Then we can say that, in your frame of reference, the car has a speed of 10m/s. Now suppose that a blue car goes by in the other direction at 15m/s. We can say that, in your frame of reference, the blue car has a speed of 15m/s.

Now, suppose that you're in the blue car, travelling along the road, and the red car passes you in the other direction. In your frame of reference, the red car has a speed of 25m/s, and you have a speed of 0m/s.


Taking frames of reference into account is important. I could state that the red car has a speed of 1000m/s, and it would be true, in a certain frame of reference.

[Edited on 12.08.2010 8:49 PM PST]

  • 12.08.2010 8:48 PM PDT

I don't care. I really don't.


Posted by: Tupolev

My interest is piqued. What would a model of the universe that does away with the concept of time actually look like?


Don't ask me, I'm human like you and humans are designed to feel that time exists even if it doesn't, just to keep our minds from losing a sense of perception and becoming unstable.
If that is true, we have to be careful or we might become insane if we make a mistake.

And the flat Earth theory was actually reasonable so long as you lived in a small region mapped on a very large sphere. In that sense, flat Earth theory has not been "disproven" so much as generalized, in the same sense that special relativity generalizes Newtonian mechanics to situations with nonnegligible relative velocities.

The other, larger issue with your example is that the moment a capable scientist came up with a plausible way to put the flat Earth theory to the test, way back thousands of years ago, it was shown to be false. Furthermore, SR became popular not because it was some cool thing but because competing theories such as ether theory began to look iffy and nonsensical in light of observations of the time; early SR theorists had to fight for it.


But flat Earth was disproved becuase someone could test it; we cannot test if time exists or not becuase nor can we test the relativistic effects (i.e. arriving before you technically left) becuase we have no FTL yet; we haven't even left the solar system, and as soon as we discover FTL (which is undoubtely possible just tremendously difficult) then is when we can test if time exists or not and/or check if we arrive before we left for our destination.

It doesn't really matter what slipspace has, though. If special relativity holds in real space under regular conditions, then the causality issue pops up. Again, my argument is not dependant on what happens to the spacecraft and what it experiences in the interem. If it is at Earth at t=0 and at Centauri at t=1 in Earth's frame of reference, then regardless of what happened between t=0 and t=1, there is a frame of reference such that the craft exists at Centauri prior to its launch, as long as SR holds in real space.

But there cannot be effects as they are not traveling through this dimension, so the effects won't appear because because normal spacetime effects are not aplicable with a dimension with only space and no time.
And the effects won't appear in this dimension as if you look at this dimension and see where they leave from/arrive they simply appear, then reappear somewhere else in a few weeks time, therefore are not technically going FTL in this universe as they aren't even exisiting in this universe, but in another where there is no spacetime and therefore cannot be effects applied to a spacetime universe.

I was under the impression that we were moving FTL relative to far-off objects because of expansion of space itself, not because of the big bang's explosive energies. And also that that relative motion has no bearing on the casaulity breaking aspects of FTL travel according to SR in a localized sense.

It is one and the same. We are moving FTL, and they are moving FTL, and therefore we are both moving at FTLx2 when compared to each other.
Note: I don't want to get into this as we both have different theories I am assuming; you believe space is expanding, whereas I think objects are simply moving as I think space is already infinite and therefore cannot expand further unless it becomes P (Potato; an impossible number such as Infinity+1 or Ininity x 2).

This is a confusion of definitions. Cherenkov radiation is given off when objects move faster in a given medium than light waves travel in that medium. It has nothing to do with objects moving faster than c.

Such as space itself. That means an object can move FTL in any medium; if it can do it in one, it can do it in another, however it may be much more difficult (such as running through matter in a gas state compared to running though matter in a liquid state).

Hmm. I've heard there's been some wonky research into those particles, but I'm not familiar with it. A quick google and wikipedia search only informed me that, supposedly, some neutrinos were measure moving at slightly over c, but not such that they were definitely moving at greater than c given confidence bounds.

If you can move faster than c at all, then you can move faster than c by millions of times. Again, just difficult.

Wow, this is interesting. I hope this doesn't count as Off-Topic.

  • 12.08.2010 8:57 PM PDT

This is really interesting. And i am slowly starting to understand.
BUT to simplify further if i can.

What does time have todo with space travel at ultra fast speeds anyway?
I mean Time is basically an invention of human beings.. to give measure to the length of a day, year, etc... Can't you just take time completely out of the equation.
The only way i can see time comming context of FTL travel is how much time it actually takes to go from a to b.
If i drive from my house to Toronto at the speed limit it takes 4.5 hours...Does it feel longer for the people waiting for me in Toronto or does it feel longer driving?

[Edited on 12.08.2010 9:37 PM PST]

  • 12.08.2010 9:34 PM PDT


Posted by: Tupolev

Posted by: LoneRanger 521
What is frame of reference? is this like "In this hypothetical situation" or something like that?

Suppose that you're sitting in a chair on the side of a long, straight road, and you see a red car go by at 10m/s. Then we can say that, in your frame of reference, the car has a speed of 10m/s. Now suppose that a blue car goes by in the other direction at 15m/s. We can say that, in your frame of reference, the blue car has a speed of 15m/s.

Now, suppose that you're in the blue car, travelling along the road, and the red car passes you in the other direction. In your frame of reference, the red car has a speed of 25m/s, and you have a speed of 0m/s.


Taking frames of reference into account is important. I could state that the red car has a speed of 1000m/s, and it would be true, in a certain frame of reference.


Okay is this like when ur sitting on the subway at the station, and the other subway going the other direction pulls in and stops. Your train starts moving again,.. The way you see it, the other train looks like its moving even tho its not - and your train looks like its still sitting at the platform?

  • 12.08.2010 9:43 PM PDT
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  • Exalted Legendary Member

UWG

My jokes, so I don't lose them (ignore this):
ZedFish's Opinion on Sgt. Foley.
ZedFish's Forerunner Rickroll.

The way the FTL 'jumps' work is not by "bending space and time", but rather exploiting a 5th dimension (If X, Y, Z and Time are the other 4); Slipspace. It's like an underlying fabric, while not being an underlying fabric. Shaw-Fujikawa FTL Drives effectively tear through this underlying fabric and use it as a 'new' universe temporarily to travel (as opposed to the existing one with Space [X,Y,Z] and Time) separately to the existing universe.

For memory, FTL jumps are not instant, meaning 'real-universe' time is spent in Slipstream Space, while not nearly as much as the actual non-universe time spent in Slipspace.
For example: Say, I jump from Earth to Reach. It takes two days "normal" time. This may take much longer in Slipspace (say, two months) with Slipspace-Time and Space-Time being scaled differently.
During these Slipspace journeys, those two days of real-world time are used to describe the speed of the ship, as in; "This ship travelled from Earth to Reach in two days", which should work out to 9.93355483 × 10^13km (99,335,548,300,000km) in 48 hours, or 2.06949059 × 10^12 km/h (2,069,490,590,000km/h), which is much faster than Light's (or any other wave of the electromagnetic spectrum's) 3.00^8m/s, or 1,080,000,000km/h.

CLEANED UP:
Earth-Reach in two days- 2,069,490,590,000km/h
Light- 1,080,000,000km/h

Earth-Reach = Faster than Light (FTL)
[Correct me if I'm wrong]

Because Slipspace isn't using Space-Time, you can't distort the Space-Time with an FTL drive.
...unless something malfunctions. Then you're gonna have some crazy stuff to talk about, if you live.

If any of this didn't make sense, sorry. It's most likely because I've been rambling.

[Edited on 12.08.2010 10:15 PM PST]

  • 12.08.2010 10:00 PM PDT

If we know all this -blam!- about space.
Remind me why we aren't fully exploring space

[Edited on 12.09.2010 6:41 AM PST]

  • 12.09.2010 6:40 AM PDT

I don't care. I really don't.

Because we aren't actually sure about this stuff. Plus governments are more interested in building nukes and drilling for oil than investing money in space travel. We've had the tech to put people on Mars since 1969. Have we been there yet? Only rovers.

  • 12.09.2010 8:33 AM PDT

Can someone confirm/deny/explain this:

If one source sends light in one direction, and another source sends light from the opposite direction, if you were observing from within the first light, would the incoming light from the opposite end appear to be moving at lightspeed x 2?

It probably makes no sense, but theoretically, would it work?

  • 12.09.2010 10:29 AM PDT

I don't care. I really don't.


Posted by: HereComesAlex
Can someone confirm/deny/explain this:

If one source sends light in one direction, and another source sends light from the opposite direction, if you were observing from within the first light, would the incoming light from the opposite end appear to be moving at lightspeed x 2?

It probably makes no sense, but theoretically, would it work?


It makes perfect sense as this is what it would be like. For exapmle, you have two cars moving towards each other, each going at 25 kilometers per hour.
Then you have them keep that speed and smash into each other. What is the force of that collision? It is the two forces added onto each other, which is equal to 50 klometers per hour, yet no car was going over 25 kilometers per hour.
It is the same from viewpoints. It's also why cars going opposite directions from yours seem to be passing by faster than if you were parked on the side of the road.

P.S. This isn't an info thread, this is people trying to find out if Slipspace would cause time distortion/travel like FTL within this universe or if because of its seperate universe nature would have no such distortion effects. And believe it or not, most of it is. Yes, physics are annoying and complex.

[Edited on 12.09.2010 11:02 AM PST]

  • 12.09.2010 10:53 AM PDT

Sorry if it's a bit off topic then. I know that in the car example this was based on it makes sense, but does that still hold up when both objects are moving at what is considered the speed limit?

  • 12.09.2010 10:55 AM PDT


Posted by: SCARFACE71795
If we know all this -blam!- about space.
Remind me why we aren't fully exploring space

Because it's costly and has no sure economic benefits. Rockets are expensive, and our rocket building technology hasn't improved much since the 60's; actually, as it happens, many of the base models of rockets still in use today were designed in the 1950's and 60's, such as the Russian Soyuz rocket.

The problem is, you need something with a very high thrust-to-weight ratio to get a craft into orbital and superorbitar trajectories, and it must continue to work even in the upper atmosphere. This requires rocketry under our current technology, and that's expensive.

And yeah, the main thing is, not much immediately visible economic benefit. They fund as much space research as they see profitable.

Can someone confirm/deny/explain this:

If one source sends light in one direction, and another source sends light from the opposite direction, if you were observing from within the first light, would the incoming light from the opposite end appear to be moving at lightspeed x 2?

It probably makes no sense, but theoretically, would it work?

You can't really "observe" from the first light, since time wouldn't pass for a light-speed reference frame relative to the rest of the universe at all.

In any case, regardless of what normal reference frame you're observing from, the observed velocity of the light in any localized situation is going to be c (as long as the light is propogating through a vacuum; some media can slow light waves down).




Let's look at another situation, ditching the idea of things moving "at c". Suppose in a given reference frame, two objects are moving at a very high fraction of c, and let's call their speed v. Then, in the reference frame of one of the colliding objects, the other object will be headed its way at a speed greater than v, but lower than c.
Velocities according to relativity are not directly additive.




P.S. This isn't an info thread, this is people trying to find out if Slipspace would cause time distortion/travel like FTL within this universe or if because of its seperate universe nature would have no such distortion effects. And believe it or not, most of it is. Yes, physics are annoying and complex.
It's actually not. I've explained time and time again that, if SR holds in real space, the actual distortion effects on the craft itself are irrelevant in the causality-breaking argument. If all you know is that at t=0, the craft is at Earth, and at t=1 in Earth's reference frame the craft is at Alpha Centauri, then it is possible to find a reference frame (pretty easy to do in this case, just take v=.99c and you're probably good) such that the craft arrived at Alpha Centauri prior to taking off from Earth. What the craft may or may not have done in the interim is 100% completely irrelevant. It doesn't matter if the craft itself suffers from spacetime distortion or not because what the craft experiences in irrelevant in the argument, and the only thing I'm taking into account is what Earth's reference frame sees and what some reference frame with a high relative speed to that frame sees.

We might as well not go on continuing this argument though, since we have completely irreconcileable zero points. I'm trusting the assumption of modern physics that SR holds in local space as long as you don't take extreme gravitational effects into account (at which point GR must be considered), and you're assuming it just plain doesn't.

Which is why I'm still concluding that the Haloverse effectively ditches modern physics, like most sci-fi universes.

[Edited on 12.09.2010 12:03 PM PST]

  • 12.09.2010 11:54 AM PDT

I don't care. I really don't.


Posted by: Tupolev

Maybe you're having such a hard time is becuase most people don't know stuff like you do. You siad it's not comlex, and yet your counter response was quite complex. How did you learn such physics terms?

  • 12.09.2010 12:27 PM PDT

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