Large Hardon Collider

[zoobernut]

If the black hole disappeared, the space around it would take time to recover. The effects would propagate at the speed of light and create gravity waves.

So the current theory is that spacetime is elastic but it is more like memory foam where it will eventually return to its original state if the warping object is removed however its rate of return is not instant.

Also Max those diagrams are interesting but doesn't the warping or gravity wells go out in every direction from an object? I know those are very simple representations but if we wanted to do a more accurate representation then the gravity well would be a sphere around the entire massive object?

[Mizango]

This one is correct, if I'm understanding your analogy correctly. The Earth would be like an object on the sheet, and objects are like a mark or a dot on the same piece of fabric. The Earth presses the fabric down, and the fabric around it is pulled in towards the indentation, causing objects to fall towards the Earth.

Correctamundo!

Also

Sunday at 9PM, the science channel is having a show about the LHC. I figure anyone reading this topic would also be interested in that show as well.

Funny you should mention that, I was going to leave you an offline on yahoo when I got back to the office about that. Glad your on top of that lol.

[Khamsin]

If the black hole disappeared, the space around it would take time to recover. The effects would propagate at the speed of light and create gravity waves.



This one is correct, if I'm understanding your analogy correctly. The Earth would be like an object on the sheet, and objects are like a mark or a dot on the same piece of fabric. The Earth presses the fabric down, and the fabric around it is pulled in towards the indentation, causing objects to fall towards the Earth.

No, the mark on the sheet represents some reference point of spacetime itself, not an object in spacetime. You could replace "mark" with "grid point".

In both cases, the infinitely stretchy rubber sheet and the unstretchable linen sheet will indent and cause a marble placed on the sheet (an object in spacetime) to roll toward the indent. It's just a question of the properties of the sheet itself.

By the way, is this "extended radius" and "extra space" simply because measuring along the deformed surface from the outer rim of the indent down to the bottom is longer than just measuring straight across (e.g. as when viewing from above)?

Like measuring the radius of a cone by measuring down the side to the tip, as opposed to straight across the end.

[Redivider]

so the world isnt ending?

[Woozie]

So the current theory is that spacetime is elastic but it is more like memory foam where it will eventually return to its original state if the warping object is removed however its rate of return is not instant.

Also Max those diagrams are interesting but doesn't the warping or gravity wells go out in every direction from an object? I know those are very simple representations but if we wanted to do a more accurate representation then the gravity well would be a sphere around the entire massive object?

The rate of return couldn't be instant. That would imply that gravitational effects can propagate instantly (meaning faster than light).

The diagrams Max posted are useful visualizations that people create for the sake of teaching. A three dimensional diagram would *technically* be more accurate but visually wouldn't be as instructive. A perfectly accurate diagram is impossible to reproduce because it's not possible to visualize the exact bending of spacetime. So we have to make do with a two dimensional sheet analogy.

No, the mark on the sheet represents some reference point of spacetime itself, not an object in spacetime. You could replace "mark" with "grid point".

In both cases, the infinitely stretchy rubber sheet and the unstretchable linen sheet will indent and cause a marble placed on the sheet (an object in spacetime) to roll toward the indent. It's just a question of the properties of the sheet itself.

By the way, is this "extended radius" and "extra space" simply because measuring along the deformed surface from the outer rim of the indent down to the bottom is longer than just measuring straight across (e.g. as when viewing from above)?

Like measuring the radius of a cone by measuring down the side to the tip, as opposed to straight across the end.

I used an object in my example, but if instead of an object, we make some sort of marker that could draw on the fabric of spacetime itself, we could draw dots or grids on space time and see it bend when gravity is introduced. So yeah, replace "mark" with "grind point" and each grid point is warped and moved in the presence of gravity. It's a property of the sheet itself.

so the world isnt ending?

It will when Miz stops breaking the LHC. I'm guessing the LHC isn't going to up and running until December 2012.

[ClarkSammich]

I'm guessing the LHC isn't going to up and running until December 2012.

The LHC is actually a beacon for the aliens that are piloting planet X towards us.

[Mizango]

lol Woozie

[guartz]

Correct me if I'm wrong, Mizango, but what you say sounds very familiar. I think I read it in "brief history of time", so my question is, was anything new learned since then?

[Merovingian]

sry for the dumb question.. Let say i draw a imaginary line from Earth to a star, would the line actually hit the star? would the star be in the same position that i see it on Earth? or would all the light bend, gravity thing deviate the light from the star to a different position?

[Mizango]

Correct me if I'm wrong, Mizango, but what you say sounds very familiar. I think I read it in "brief history of time", so my question is, was anything new learned since then?

The black hole post and the gravitational lensing is common knowledge and has been for quite a while. I've read that book so I know what you are referring to but what specifically are you wondering about?

Just physics of a Black hole or recent findings in regards to SMB's? Like the one at the center of our galaxy?

[guartz]

The black hole post and the gravitational lensing is common knowledge and has been for quite a while. I've read that book so I know what you are referring to but what specifically are you wondering about?

Just physics of a Black hole or recent findings in regards to SMB's? Like the one at the center of our galaxy?

whats SMB?

[Mizango]

Super Massive Blackhole. A real Titan of the Cosmos.

[Enygma55]

sry for the dumb question.. Let say i draw a imaginary line from Earth to a star, would the line actually hit the star? would the star be in the same position that i see it on Earth? or would all the light bend, gravity thing deviate the light from the star to a different position?

First you have to consider the distance of the star. Being 50 light years away means the light you see is where the star was 50 years ago ( because it took 50 years for the light to reach the earth ) so there might be slight deviations due to galaxy rotations, cosmic drifting and whatnot that alters its actual position.

I'm not too familiar with how light works around Gravitational lensing so cant comment on that .

[guartz]

Super Massive Blackhole. A real Titan of the Cosmos.

If they find one bigger, will they call it Super Duper Massive Blackhole?


Tbh I know nothing about that? Blackholes are suppose to be really small right?

[Woozie]

If they find one bigger, will they call it Super Duper Massive Blackhole?


Tbh I know nothing about that? Blackholes are suppose to be really small right?

The actual physical extent of the material that makes up a black hole is exactly zero according to relativity (though this contradicts quantum theory, but let's ignore that fact for now. The point is, you're right, black holes are incredibly small).

The word "Supermassive black hole" refers to the mass of the black hole, not the physical size (you probably already know this because of the word "massive" in the title, but for some reason I'm explaining it anyway). A supermassive black hole is infinitely small just like any other black hole, but is MUCH more massive and thus has much higher gravity. This also means that the distance from the singularity to the event horizon is larger. I regular black holes have an event horizon that's only a few miles radius, so even if you measure it this way they're still pretty small on the cosmic scale.

Edit: And yes, they probably will call it that because physicists have no creativity when it comes to naming stuff (up, down, top, bottom, strange, charm, gluon, red, blue, green, sparticles, etc.)

[aalryn]

Blackholes are suppose to be really small right?

Not necessarily. They just have an amazingly large amount of mass per unit of volume. You'll hear the saying such as "imagine the mass of the earth the size of a pinhead" or something to that effect. That is just to put the mass into proportion, not the physical volume of it.

[Jer]

In terms of the event horizon, they can be. They are classified based on mass. Though obviously, the more mass it has, the farther out it's event horizon will be.

[Woozie]

Not necessarily. They just have an amazingly large amount of mass per unit of volume. You'll hear the saying such as "imagine the mass of the earth the size of a pinhead" or something to that effect. That is just to put the mass into proportion, not the physical volume of it.

You're right, any object can become a black hole if it's dense enough, which would create an incredibly dense black hole, but not infinitely small. Then there's no limit on how large a black hole can be as long as it stays dense enough.

However, after such an object is created, it will inevitably collapse into a singularity and become infinitely small anyways.

[guartz]

okay.

This begs the question, what exactly, is gravity?

[Woozie]

Gravity is usually defined as the actual bending of the fabric of space-time, though this definition isn't enough for a Quantum Theorist.

There is a better way to answer this question, we just don't know it yet. Different theorist have different opinions of what *exactly* gravity is.