Large Hardon Collider

[Khamsin]

Now, my next question would be, in those "weight on a sheet" analogies, you place a weight on the sheet and it only sinks down so far. Is there a point where enough weight on a small enough area would cause the object to keep sinking? e.g. imagine space-time as infinitely pliable play-dough, and on a thin sheet of it you can place light objects that only sink in a bit but stay. A heavy enough object would sink and just keep going, slowly at first but picking up speed as it goes. Normally, a thin sheet of play-dough would tear at this point and the object would just drop through. But say this is infinitely pliable and will just keep stretching as the object sinks. This creates steeper and steeper slopes in a small area around it, and exponentially increases surface area.

Now, imagine that the rest of the sheet gets drawn down a bit, too. Like, say, an artesian well drawing down the water table. Near the well, slopes are steep and asymptotic at the center. Further from the well, even at great distances, the water table is drawn down only a tiny amount, but still influenced by the well.

If you were at some point outside the "event horizon", where the slopes are steep, but still within the area of influence for the draw down effect, you would see the surface area all around you grow exponentially as the object at the center sinks ever further. Despite not being close enough to tumble down the slope.

Could the expansion of the universe be influenced by some giant ultramegasuperdupermassive black hole "drawing down" the fabric of the universe around it, stretching it faster and faster as time goes on, and we're somewhere in the middle of one of the side slopes (but not within the event horizon), observing the increase of surface area as a result?

Then again, if that were the case, we'd observe expansion in only two directions: toward and away from the center. But expansion is probably being observed in all directions equally. Unless we are in the event horizon and are looking up out of our hole as we sink deeper, observing everything getting further away as we go.

[Mizango]

Exactly, anything is a possibility at this point in regards to possibility of "us" as we know being a part of a larger more intricate system. Then again toeing the line to M-Theory or Super strings can be mind numbingly BLAH.

That sheet analogy you used in the first paragraph is spot on and explains the functionality and gives visual reference to Black holes as well as to Super massive black holes like we have at the center of our Milky way galaxy and other spiral galaxies. Its fun to imagine hypothetical scenarios where black hole actually do rip and tear the very fabric of space and man's attempts at replicating the process.

There are all sort of theories and on going studies regarding worm holes and the tearing and re-stricthing (for the lack of a better word) of space. But all in all you hit it right on the head.

[Max™]

By the way, back on the "weight on a sheet representing gravity" analogy, would the indentation and contours of space-time affect perceived distances? e.g. when you place a marble on a sheet with a weight on it, it rolls down the contour toward the low point, representing gravity. However, this means the marble travelled farther to that point than if the sheet were flat (assuming it follows the surface of the sheet at a constant speed as it goes over the various contours in the fabric). And the heavier the weight, the further depressed the sheet is, and the more surface area there is on the sheet.

Will we feel this extra distance, compared to the sheet being flat?

Will it take us longer to go from point A to B when a heavy object is in the middle than if there were nothing?

That's Gravity!


The distances are distorted in the gravity well such that "straight" path across the well is no longer "straight", rather the straight path is bent towards the massive object.

There is literally more space, more distance, towards the center of the Earth, than if you went a distance equal to what the radius of a circle the Earths diameter would be in a lateral direction from the surface.


As for occupying the same space in the singularity, that is an artifact of point particle concepts, which are utterly unrealistic.

You can't have two things in the same space, trying to represent it mathematically produces infinite runaways, that's the original problem that got me into physics, how can you have something which exists, but has no physical extent, you could pile more and more of them on top of the first one without it getting any larger, yet reality does not work like that.

[Khamsin]

Also, what is the reasoning behind why a massless photon can't escape a black hole?

And is the universe expanding faster or slower (or at) the speed of light?

Lastly, can space-time itself stretch or deform faster than light (since it's not an object in space, it is space itself)?

e.g. if I had a taut rubber band with a photonic ant crawling across it at the speed of light, can I stretch the rubber band fast enough to keep the ant from ever reaching the other end?

[Murdock]

this was just posted on Yahoo News.

Particle collider: Black hole or crucial machine? - Yahoo! News

[Max™]

I'm fairly certain you could think of an event horizon as an edge in the Universe.

There is no escape, because from the inside your degrees of freedom are different.

You can move around through time, and around the deepest point in the well, but you can only move towards, never away from that point.

Kinda like asking why water doesn't climb out of a cup.

The rate at which the Universe is expanding can be greater than the speed of light traveling through the Universe, they are two different things.

One is an effect within a medium, the other is a broad change in the state of the medium itself.


If inflation is correct, there were pockets of the early Universe which expanded quicker than light could have crossed them, making lightspeed domains, distinct from one another til later on after the expansion slowed down, so yes, you could expand a rubber band quicker than the photon ant could move along it.

[Kryssan]

Bah, science isn't cheap. Money spent on the LHC is better there than about all the places our governments keep spending it instead. Besides, 10 billion is rather cheap, what with all the money getting thrown around right now anyway. Especially for a structure that's 17 miles of awesomeness.

[Eliseos]

Also, the speed with which you observe the universe expanding depends how far you look back. One of Hubble's (the Astronomer, not the telescope) big accomplishments was that he noticed that the further away a galaxy was to us, the faster it was receding from us.

As for the LHC, I'm with Kryssan. It saddens me every time I hear NASA or some other science organization get it's budget cut.

[Khamsin]

I'm fairly certain you could think of an event horizon as an edge in the Universe.

There is no escape, because from the inside your degrees of freedom are different.

You can move around through time, and around the deepest point in the well, but you can only move towards, never away from that point.

Kinda like asking why water doesn't climb out of a cup.

The rate at which the Universe is expanding can be greater than the speed of light traveling through the Universe, they are two different things.

One is an effect within a medium, the other is a broad change in the state of the medium itself.


If inflation is correct, there were pockets of the early Universe which expanded quicker than light could have crossed them, making lightspeed domains, distinct from one another til later on after the expansion slowed down, so yes, you could expand a rubber band quicker than the photon ant could move along it.

So in that case, the "weight" in the middle of the black hole could be sinking so fast, stretching the surface and expanding space faster than a photon could traverse it. You could be in the black hole without being crushed, and have complete freedom of movement (from your perspective), but still never be able to leave because space stretches faster than light in that area.

Inside, you'd look out and see the universe expanding and accelerating. And even though you would be forever drawn further down into the well, you'd perceive unrestricted movement, like the ant on a rubber band. Outside, people would see a "hole" of nothingness confined to what appears to be a small point.

Also, if spacetime is curved by gravity (or anything, for that matter), does this make a 5th dimension? Our perceived three dimensions, time, and the depth of the indents on the sheet (with gravity being represented by the gradient of the surface of space-time).

[zoobernut]

So in that case, the "weight" in the middle of the black hole could be sinking so fast, stretching the surface and expanding space faster than a photon could traverse it. You could be in the black hole without being crushed, and have complete freedom of movement (from your perspective), but still never be able to leave because space stretches faster than light in that area.

Inside, you'd look out and see the universe expanding and accelerating. And even though you would be forever drawn further down into the well, you'd perceive unrestricted movement, like the ant on a rubber band. Outside, people would see a "hole" of nothingness confined to what appears to be a small point.

Also, if spacetime is curved by gravity (or anything, for that matter), does this make a 5th dimension? Our perceived three dimensions, time, and the depth of the indents on the sheet (with gravity being represented by the gradient of the surface of space-time).

I think it was said that this would be impossible because if it got to the point where the weight was such that it was stretching space time that fast the gravity would be vastly different from one end of your body to the other and you would get ripped apart so really unless you were a singularity yourself it would not be possible to just "float" on the other side of the event horizon and witness the universe expanding and accelerating.

[Woozie]

Also, what is the reasoning behind why a massless photon can't escape a black hole?

In Newtonian Physics, gravity is a force between the mass of two particles, so massless particles aren't affected.

In GR, gravity is the distortion of the fabric of spacetime. So anything traveling through spacetime is affected regardless of whether or not it has mass. Since the way gravity affects spacetime is by curving it, we see light bending around heavy objects. If space is curved severely, the light bends severely. In the case of a black hole, the bending is so severe that the light only has one direction it can go - towards the singularity.

[Woozie]

And is the universe expanding faster or slower (or at) the speed of light?
e.g. if I had a taut rubber band with a photonic ant crawling across it at the speed of light, can I stretch the rubber band fast enough to keep the ant from ever reaching the other end?

The universe is expanding slower than light, but the expansion will become faster than light if cosmic dark energy doesn't calm down. This will lead to the big rip, which you've probably already heard about. To use your ant on a rubbber band analogy, photons and gravitions (and the other force carriers) will be like ants, never able to reach any other object in the universe because the rubber band is stretching faster than it can crawl. Every single particle will be it's own isolated island, never able to be pushed, pulled, attracted, or repelled.

[Pirian]

The universe is expanding slower than light, but the expansion will become faster than light if cosmic dark energy doesn't calm down. This will lead to the big rip, which you've probably already heard about. To use your ant on a rubbber band analogy, photons and gravitions (and the other force carriers) will be like ants, never able to reach any other object in the universe because the rubber band is stretching faster than it can crawl. Every single particle will be it's own isolated island, never able to be pushed, pulled, attracted, or repelled.

One thing that has really puzzled me about the whole expanding of the universe is if we're traveling through the universe at an ever increasing speed, and because time goes slower as we speed up, does this mean that the time we're experiencing is actually less than the universe at rest experiencing? In other words, is time is slowed down in our galaxy because the galaxy as a whole is traveling at such a high speed? If this is the case how can we accurately say how old the universe is because we're traveling faster the things that aren't moving as fast as us will seem to be moving slower, won't they?

I have more questions but I'll stop with these for now in case I've got something wrong

[Max™]

The galaxy is moving through spacetime, and has a large gravity well, those both affect the motion through time of it's contents.

The expansion of spacetime itself is not the same as motion around it.

It seems as though we're at rest, and everything is moving away from us.

Yet to everything else, it is at rest, and everything else is moving.

[Enygma55]

Just some recent articles about the current status of the LHC.

Nothing really new but cool reads.


Particle collider: Black hole or crucial machine? - Yahoo! News

Large Hadron Collider to restart at half its designed energy - physics-math - 07 August 2009 - New Scientist

[Woozie]

The galaxy is moving through spacetime, and has a large gravity well, those both affect the motion through time of it's contents.

The expansion of spacetime itself is not the same as motion around it.

It seems as though we're at rest, and everything is moving away from us.

Yet to everything else, it is at rest, and everything else is moving.

What he said. You have to realize that the galaxies aren't flying around through spacetime like a rocket ship moving nearly light speed would. The expansion of the universe is the expansion of spacetime itself.

Imagine drawing a balloon and blowing it up partially. Then draw a bunch of dots on the balloons. The dots represent galaxies. The balloon is the fabric of spacetime. If you blow the balloon up more, the dots all move away from each other. But they aren't moving through the fabric of spacetime, the fabric of spacetime is what's actually moving. The dots aren't getting far away because they're moving across the balloon. They're getting farther away because the space between them is expanding.

From of the point of view of every dot, it appears as if it is standing still and everything else is moving away. No dot can be said to be the center of the balloon or the center of expansion.

[Woozie]

If any lovers are awake right now, you should be watching history channel.

Edit: My bad, science channel, not history.

[Woozie]

They just got done talking about a presentation Feynman gave on QFT. When his presentation was done, he was ridiculed by all of the top physicists. They went as far as to say he didn't know anything about Quantum Mechanics (which is like saying Jordan doesn't know anything about basketball). It's funny how someone can have this kind of a start and end up being the most legendary figure in all of physics (arguably. personally, I'd put him in the top tier with Newton and Maxwell and maybe a few others, but I know someone out there will disagree).

[Pirian]

From of the point of view of every dot, it appears as if it is standing still and everything else is moving away. No dot can be said to be the center of the balloon or the center of expansion.

Hubble's law, yeah I understand that. Let me phrase my question another way: say we happened to find a way to leave our galaxy. We would have to faster than the universe is expanding in order to reach another galaxy, and that can be measured, right? Just like how a fly on a train doesn't realize it's moving at the speed of the train. Or rather, lets use your example of a balloon: the ant on the ever expanding balloon is at point A. In order for the ant to make it to point B he has to overcome the rate at which the balloon is expanding, and that can be measured. Furthermore, as the ant gets closer and closer to the speed of light everything around the ant, from the ants prospective, starts to slow down. Therefore the ant perceives the rate of expansion of the balloon to be slower than it actually is the faster the ant goes.

Edit: Going out to brunch or I would turn on the tube

[Kryssan]

They just got done talking about a presentation Feynman gave on QFT. When his presentation was done, he was ridiculed by all of the top physicists. They went as far as to say he didn't know anything about Quantum Mechanics (which is like saying Jordan doesn't know anything about basketball). It's funny how someone can have this kind of a start and end up being the most legendary figure in all of physics (arguably. personally, I'd put him in the top tier with Newton and Maxwell and maybe a few others, but I know someone out there will disagree).

“On a paper submitted by a physicist colleague: ‘This isn’t right. This isn’t even wrong.’”

That's all I have to say about that. But, its a sad fact of life that the greatest scientific inventions and their creators always arrive before their time and are hardly ever recognized during their lifetime. Though humans claim to reach for the unknown, we breed our contempt in the familiarity of tradition.