Moving at light speed

[Queso]

Sorry for pointing this out but you accepted that answer rather quickly.

heh, i've been actually trying to grasp it for about a year now ;) and YES, of course i'm curious about how the universe began. i love learning/thinking about these kinds of things.

[Queso]

with the balloon analogy in hand:

 

point A is on the top of the balloon.

point B is on the bottom.

there is a line that connects them on the surface, and there is a line that connects them through the balloon.

 

the line that connects them through the balloon is a wormhole right?

[Buffy]

the line that connects them through the balloon is a wormhole right?

That's a pretty darn good analogy! the idea is that the concept of "through the balloon" can't be perceived by 2-dimensional beings, and would be equivalent to magic or transdimensional slipstream warpdrive....

 

Cheers,

Buffy

[Queso]

amazing! ! ;)

one more question.

does this wormhole use other dimensions to exist, or is it still in 3 dimensions?

[Buffy]

They get drawn/conceived as "tunnels" (the pictures you may have seen, or Slipstream on Andromeda), but I think the idea is that if one were to exist it would be more like a door: one side is one place, the other is another place, with nothing in between. Its all conjecture, but I don't think Kip Thorne (at Cal Tech who has done the most serious research on this) required an extra dimension to explain it. Kip though sez you'd have a hard time getting one big enough to pass more than an atomic particle through one, even if you were able to open one up.

 

Cheers,

Buffy

[Tormod]

Now all of the particles and anti-particles didn't explode out of a point: they exploded within the point. This makes some sense to me. The point grew extremely quickly as is my understanding. So there is no point within this point that is the centre. So I must assume you are saying that this point was filling with particles as it expanded.

 

The important thing about the Big Bang theory is that particles were not present until after the "point" had started expanding and it had some time to cool down.

 

I write "point" because it was not a point anywhere in space - because what was to become spacetime was born when this "point" started expanding (which is when the Big Bang happened). Nobody said this was easy.

 

But - and this is the important part - this is *theory*. We can't observe the Big Bang. We can only make up theories and test them. So far we have fairly good explanations of what happened back to a vanshingly small fraction of time after the Big Bang. But everything we think we know may in fact be wrong. That is how science works...

 

With regards to a black hole the matter apparently gets pushed into the particle point.

 

It is not a point. If it is a singularity, as many theorists claim, then it is an infinitely dense area packed into an area with no definite size. This would be a "naked singularity", wrapped within the event horizon which would make it impossible for us to see it (John Barrow has some interesting ideas about this in his Infinite Book).

 

String theorists do away with the singularity because there is no need for it.

http://www.damtp.cam.ac.uk/user/gr/public/qg_ss.html

 

As for myself, I don't know what's inside a black hole. But I don't think it's a pinhead full of endless matter.

[Tormod]

amazing! ! ;)

one more question.

does this wormhole use other dimensions to exist, or is it still in 3 dimensions?

 

Use a pen to write A and B not too far away from each other on a balloon. Imagine that an extremely strong gravity field was created somewhere along the balloon - so strong that it warps the balloon to the extant that two parts actually touch (like when you pinch the balloon). So put your index finger on A, your thumb on B, and squeeze until they meet.

 

Now what has happened to the distance between A and B? It is gone. But how do traverse the distance? Hm....

[Queso]

yes. thanks for answering these questions, this topic fascinates me.

[Damo2600]

O.k. guys I have had a couple of hours sleep and am ready to get back into it.

 

Now I will start with relativity. In one of your links, Tormod, it shows the time dilation with regards to observable light, for different observers at different velocities. Which is pretty much the same example used in Einstien's paper.

 

But I can use the same example to show that the time dilation is merely appearance. Imagine two towers both 20m in height. One however is on wheels moving toward the other. A top of each tower sits two observers. Each observer has a clock and prior to the experiment all clocks were syncronised. The first observer on each tower flashes a light ray down to the bottom of the tower which is reflected back up to the top of the tower and the observers record their elapsed time. The second observers record the elapsed time of the light rays with regards to the opposite towers. The two towers meet up and all four observers compare results. All of the clocks remain syncronised. The first two observers recorded equal elapsed time for the light rays they observed.

 

(Break to give your eyes a rest.)

 

The second observers give equal yet slightly longer elapsed times than the first two observers. The two towers were symetrical and the results were also symetrical. The experiment could also be reinacted with a mirror at half way and the velocity of the tower cut in half. In this case the stationary tower doesn't need to exist. Keep this in mind. The second observer on the first tower observes an event that happens relevant to the first observer on the second tower. Their recorded times are different. However if the second tower is merely a reflection of the first tower then both observers are actually stationary to each other and their respective time frames are exactly the same.

 

There IS no time dilation it is merely an illusion created by the movement.

 

I understand however that it is much more difficult to discern the illusion if: Qwfwq is stationary in space and I travel at 60km/s parallel to his line of sight, Tormod is travelling at 3000km/s on a tangent to his line of sight, and Buffy is travelling at 200 000km/s in a curving tragectory. In this case complex mathematical transformations are needed to decipher the true meaning of such events. However all our time frames are actually equal. We just observe them in a completely non-uniform manner.

 

Do I get an A for understanding the basics of special relativity?

 

Damien

[Damo2600]

Now for the big bang. Just make sure we are on the same page here:

 

 

The model you are offering me is explained as a sphere. I am gathering this is what is known as a closed universe. I am sitting on the edge of this sphere. Now if I travel in one direction, in a straight line away from earth I would be in fact travelling the circumference of this sphere. So if it were possible for me to travel at speeds greater than c for long enough, without changing direction, are you saying that I would eventually return to earth and smash into it?

 

I'm not totally clear on this.

 

Damien

[Damo2600]

In case you miss it I have posted two messages previously to this one.

[Buffy]

The model you are offering me is explained as a sphere. I am gathering this is what is known as a closed universe. I am sitting on the edge of this sphere. Now if I travel in one direction, in a straight line away from earth I would be in fact travelling the circumference of this sphere. So if it were possible for me to travel at speeds greater than c for long enough, without changing direction, are you saying that I would eventually return to earth and smash into it?

That's right! Weird huh?

 

One slight clarification: to you as a 2-d person, you cannot conceive of a sphere, so you do not perceive the "Universe" you live in as one. Extrapolating, our 3d universe is not a sphere, and its not expanding from a central point as if you were blowing up a balloon or setting off a firecracker....

 

Cheers,

Buffy

[Damo2600]

O.k. That sure is WEIRD.

 

I'm not sure what happened to all the gases that existed before the big bang. Do they fit into this model? So according to this model before the big bang spacetime did not exist as a closed universe?

 

Between Earth straight through the middle of this sphere and out the opposite side no space exists. I am equally on earth and at the other side of the universe at the same time. What I mean by this is no space exists between myself and any other part of the universe.

Due to the fact they are all connected through the centre of the sphere. Currenlty I am on earth but in an instant I could be somewhere else by crossing the non existent centre. So infact you are stating that we don't exist in a 3d spacetime but a spacetime with infinite dimensions stacked on top of each other.

 

This is wierd to me and I am just trying to comprehend your model.

 

Damien

[Damo2600]

One slight clarification: to you as a 2-d person, you cannot conceive of a sphere, so you do not perceive the "Universe" you live in as one.

 

Sorry I don't get this post at all. I'm a two dimensional person now. I just got a flash of homer colapsing into our 3d world and myself colapsing into the 2d Springfield.

 

Damien

[Queso]

springfeild is actually a 3d world projected as 2d.

a good example of 2d is old mario.

[Damo2600]

Hang on Buffy I think I understand you.

 

In your model:

Supposing there were 360 of me travelling in the same manner I described in one direction at v > c.

 

If I travel along the plane coordinates of the sphere in all 360degrees around the circumference I would end up where I started.

 

However the 3d part comes into it by my travelling perpendicular to the plane coordinates of the sphere, up or down I'm supposing they are all the same, I would not cross the centre of the sphere I would now be travelling a perpendicular sphere. So the sphere model you describe is O.k. as long as you realise that any direction you travel in 3d spacetime you are always travelling along the circumference of the sphere.

 

Let me ponder that.

 

Damien

[Buffy]

I'm not sure what happened to all the gases that existed before the big bang. Do they fit into this model? So according to this model before the big bang spacetime did not exist as a closed universe?

This is getting at why its so hard to comprehend. Because its spacetime not space and time, when the big bang "happened" not only was there no space, there was no time either. There was no "outside" for it to "expand into". And hardest of all is the crux of the matter: there's no sphere, there's no edge, its expanding everywhere in every direction. So to answer your question directly, there wasn't anything at the big bang (before, we have no idea, maybe it was finishing a crunch, but we have *no* way of finding out as far as we know), you can't think of it being a "singluarity sitting in a bunch of gas before it went bang."

Between Earth straight through the middle of this sphere and out the opposite side no space exists. I am equally on earth and at the other side of the universe at the same time. What I mean by this is no space exists between myself and any other part of the universe.

Oh there's space all right, but because space is curved you can go "straight" and come back to where you started (for physicists: okay, we think its actually flat which means you wouldn't quite ever get all the way back, I'm arguing its flat minus epsilon...). Worse in the case you're talking about, you'd never really know if you were "halfway" around, because there really isn't an "opposite" side of the universe and it keeps expanding so it would take much longer on the second "half" because you'd have further to go!

Due to the fact they are all connected through the centre of the sphere. Currenlty I am on earth but in an instant I could be somewhere else by crossing the non existent centre. So infact you are stating that we don't exist in a 3d spacetime but a spacetime with infinite dimensions stacked on top of each other.

Not quite: again, its not a sphere, but time is something we can't observe, yet its fundamental to the nature of what's expanding. Since its hard to visualize, it doesn't make a whole lot of intuitive sense....

 

Cheers,

Buffy