Time travel

[denoir 0]

It's very strange that the word "infinite" exists, they say the space is neverending.  But for us humans it's just impossible to understand.

It's not infinite like a line that never ends. It's infinite like a circle - it is bounded, but it has no end. Space-time is according to the current theories spherical and closed. If you go in one direction long enough you'll come back to your starting point.

Quote[/b] ]How does a black hole 'fold' space, when it's just space.  There's nothing to fold  

While humans have a special form of processing space and time, that can be misguiding.

I'll give you a simple example in 2d space.

Normal space:

Folded space:

Imagine that you want to go from one point on the edge of the circle to another by passing through the centre of the circle. In the first, case (normal, not distorted space) that distance is always the same: two times the radius of the circle.

In the second picture, the folded space, that's not true. Depending on where you pick your point and where you want to go, the results will be different. Due to the folding of the space you can travel a shorter distance (or a longer) than in the original case.

[sanctuary 19]

I remember a scientific doc on TV some years ago , there was that question "what is in the other side of a blackhole" as some SF movies tried to make some explanation

A specialist of blackhole research explained that because of the infinite density found in the blackhole , anything will just be annihilated (to go from a certain weight to an infinite weight by being captured in the blackhole is the best way to annihilate something) .

Just with this infinite density theory , i find blackholes really interesting and i never miss docs that feature a discussion between scientists with their theory about this incredible monster from outer space ;)

[Harnu 0]

I still can't picture it! I know space isn't 2D, atleast I'm hoping not because I've learned that space should atleast be 3D?

Denior, so if space folds like that, anything in it will change proportionally with it?

[denoir 0]

I still can't picture it!  I know space isn't 2D, atleast I'm hoping not because I've learned that space should atleast be 3D?

Well, just imagine another axis perpendicular to the two on the pictures. And that the circle is a sphere.

Quote[/b] ]Denior, so if space folds like that, anything in it will change proportionally with it?

If you are asking if the geometry of the any physical object within it will change, the answer is no. What it does is that it affects the motion of the object. Space-time folding gives what we see as a gravitational force.

Objects with mass deform space. You can visualise it like the deformation of foam-rubber when you put a heavy object on it. If you roll a ball on the surface it will roll towards the depression made by the heavy object. That's how gravity works.

[llauma 0]

www.superstringtheory.com

A good site for those who still haven't overheated their brains.

[Cpt.Gumbo 0]

Possible, no, now with us men anyway. I doubt it would be useful, men wrecks everything he is given so no I would be afraid for us to get ahold of it.

[Balschoiw 0]

The chances for time travel are as big as the chances for humans flying without technical help.

Arthur Douglas, author of the "Hitchhikers guide through the galaxy" solved that problem already.

To fly you simply have to ignore the ground and jump out of the window. Now comes the tricky part. You have to miss the earth and pass it. That´s it. Now you fly

I am pretty sure physicians can do a lot of funny stuff in the next years but I doubt the human beings will be able to travel in time. Objects with the size of an atom maybe, but not Mr. John Average.

Let´s bend the space continuum

Scotty beam me up.

[Tex -USMC- 0]

...

*error*

[Tamme 0]

It seems that I have different info than many others. What's right I have no idea, but as I know black holes are not infinite. If it's a rotating black hole, with a mass 10 times as big as the Sun's, you can go in and through it. Maybe even end up in a whole new world. You just have to navigate through the singularitet. (what do you call it in english?)

[NurEinMensch 0]

If you want to go "through" make sure it's actually a hole leading somewhere in the first place, and not a small point of almost infinite gravity; or it would be a veeeery short and very "heavy" trip

[Balschoiw 0]

Yeah from my knowledge black holes are products of exploded stars. Stars blow up at the end of their lifetime to red giants and fall back to white dwarfs and comprimate their mass that much that they even attract light. So you have a high comprimated mass with extreme gravity. Once you get in reach of a black hole you will be drawn towards that mass concentration and simply destroyed, right ?

[denoir 0]

What Tamme is talking about is wormholes. They're basically two black holes whose distortion of the space-time meet. It requires antimatter in the middle, which is very rare in the universe so the wormholes encountered in space would most likely be microscopic.

Furthermore there are other problems. There are some nasty side effects. The entrance of the worm hole has a form of double sided event horizon. When you enter it, time accellerates infinitely (basically you see the whole history of the universe pass by on the outside). A side effect of that is that the faster time rolls you get an increased doppler effect on the light waves, resulting in higher energy waves hitting you. The radiation energy would increase enormously and it's doubtful that the wormhole could survive being hit by so much energy.

So there is very little chance according to current theories that you could find a stable wormhole at all.

Now, when discussing cosmology, especially in connection with genral relativity one must keep in mind that this is very much work in progress. GR provides a general framework but it is very open-ended. The same goes for quantum mechanics, especially under conditions that we can only speculate about. We also know that there are some things wrong with our theories. In several fundamental cases they work good alone but not in combination with other theories.

[UniverseMan 0]

Although theoretical physics and temporal mechanics aren't my strong points, I always thought time travel wouldn't be about punching a hole, as it were, through to the past, but more of a series of actions involving quantum 'foam'. In this case, the theory is, the universe at the extreme quantum level is nothing so more than a collection of particles popping in and out of existence, and doing whatever it is quantum particles do. Now, if all points in time are now viewed not as a linear progression, but rather as what the quantum strata 'looked like' at that instant, then the question is raised: if you can reset the particles to what they looked like at that instant, have you gone back in time (ie, to the period when the image was taken)?

As to the whole alternate universe dealie, well, again, I think it's a function of quantum mechanics. If every particle has 32 (was it 32? something like that) possible quantum states, then for each combination of states that the particles are in, a different universe could exist. For what it's worth, that's the way I view the progression of time.

[Tamme 0]

It's not infinite like a line that never ends. It's infinite like a circle - it is bounded, but it has no end. Space-time is according to the current theories spherical and closed. If you go in one direction long enough you'll come back to your starting point.

Is there anyway to break through that sphere, and if you could what happens when you do?

[Necromancer- 0]

It's not infinite like a line that never ends. It's infinite like a circle - it is bounded, but it has no end. Space-time is according to the current theories spherical and closed. If you go in one direction long enough you'll come back to your starting point.

Is there anyway to break through that sphere, and if you could what happens when you do?

i speculate that you would be in another dimension

[der bastler 0]

Don't know if this was mentioned before, but regarding interstellar travels I'd say that the theory provided in BattleTech is most realistic of all sci-fi-ideas.

Charge your ship in the solar wind and then 'jump' between the stars. Jump means fold the space --imagine a sheet of paper. mark to points A and B at the edge; now fold the paper by bringing A over B...

If you can't imagine how to fold space: Think of space as a coordinate system. Let's look at a 3D-world like OFP. Every object, every polygon has it's coordinates. Now change the coordinate system by e.g. multiplying the second coordinate vector with the value 2. Now everything should look a little bit streched, because we are watching the result from our -normal- display coordinate system. But a guy inside the modified coordinate system would notice no difference because he would only know the modified coordinate system...

As a good point of beginning I recommend this book about life, the universe and everything:

"The Science of Discworld"

by Terry Pratchett, Jack S. Cohen and Ian Stewart

And, of course, don't forget "A Brief History of Time" by Stephen Hawking --a good, easy overview for the advanced reader.

@Balschoiw: I'd prefer the bistro-matic-drive...