The God Particle

[Dexter Sinister]

Isn't that assuming that something's holding you back at the top?

There is, in a sense, it's called inertia, but it's easier to describe the other way around. The acceleration is less at the top than at the bottom, so your feet will gain velocity faster than your head, and if the difference is large enough it'll pull you apart. Under normal circumstances, like standing on the earth for instance, the difference in the force of gravity between your feet and your head is pretty small, but it's there. It diminishes as the inverse square of the distance, as measured from the centre of the earth. The distance between your feet and your head is such a tiny fraction of that that it makes no sensible difference, but in a hugely stronger field, it will.

 

[karrie]

There is, in a sense, it's called inertia, but it's easier to describe the other way around. The acceleration is less at the top than at the bottom, so your feet will gain velocity faster than your head, and if the difference is large enough it'll pull you apart. Under normal circumstances, like standing on the earth for instance, the difference in the force of gravity between your feet and your head is pretty small, but it's there. It diminishes as the inverse square of the distance, as measured from the centre of the earth. The distance between your feet and your head is such a tiny fraction of that that it makes no sensible difference, but in a hugely stronger field, it will.

okay, that makes sense, thanks.

now, perhaps you can explain the 'other side' of a black hole that Praxius was talking about? Is that simply confusion between a black hole and a worm hole? Or am I confused about the concepts?

 

[MHz]

(Due to the absorbing of light a black hole does)

I;m not sure if that is the correct term. An object that emits light do so in all directions. An object between us and a black hole would be visible to us as long as it was not was not going towards the black-hole at a rate that exceeded light-speed. The gravity of a black-hole is strong enough to (eventually) make a star exceed that rate, that is when it becomes 'invisible', the object is still there in some form (matter) and it may even still be emitting light.
All this might happen quite quickly once a certain point is reached, but I don't see why this would even be associated with God. With God it is the reverse of creating a black-hole. The 'big-bang' was the opposite, more or less, once a black-hole was 'big enough' it would, well... blow up, sending everything collected back in the direction it came from.

Does all matter sucked in stay there? Since a galaxy is basically flat what are those 'streamers' that are coming out at right-angles to that plane that seems to be about where the center would be?

http://www.matter-antimatter.com/ngc_4261.htm

 

[Dexter Sinister]

now, perhaps you can explain the 'other side' of a black hole that Praxius was talking about? Is that simply confusion between a black hole and a worm hole? Or am I confused about the concepts?

Black holes and wormholes are related, in the sense that various solutions of the equations of general relativity allow for them, but they're different things. A black hole's a region of spacetime where the gravitational field is so intense that nothing can escape. Any notions about what happens when you fall into one are pure speculation, one of them being that you'll pop out into another universe. A wormhole is a topological feature of spacetime due to the curvature of the universe. If you can go through one, you'll pop out somewhere far away in *this* universe. If you can get hold of the March 2008 issue of Discover magazine you'll find some good "intelligent layperson" level discussions of these matters.

And just for interest, I've done a little back of the envelope style calculation here. If the earth's mass were compressed into a black hole (it'd be about 3 millimeters in diameter) and you were standing on it, the force of gravity at your feet would be about 250,000 times greater than it is at your head. Certainly enough to do some serious damage.

 

[karrie]

Black holes and wormholes are related, in the sense that various solutions of the equations of general relativity allow for them, but they're different things. A black hole's a region of spacetime where the gravitational field is so intense that nothing can escape. Any notions about what happens when you fall into one are pure speculation, one of them being that you'll pop out into another universe. A wormhole is a topological feature of spacetime due to the curvature of the universe. If you can go through one, you'll pop out somewhere far away in *this* universe. If you can get hold of the March 2008 issue of Discover magazine you'll find some good "intelligent layperson" level discussions of these matters.

And just for interest, I've done a little back of the envelope style calculation here. If the earth's mass were compressed into a black hole (it'd be about 3 millimeters in diameter) and you were standing on it, the force of gravity at your feet would be about 250,000 times greater than it is at your head. Certainly enough to do some serious damage.

Very cool Dex, thanks. I was pretty sure I had my notions of worm hole vs. black hole straight. But I guess 'the other side' could still apply. Weird to think. Imagine the whole world sucked through to another dimension, looking like we'd all gone through a meat grinder. Lovely thought.

 

[Dexter Sinister]

The gravity of a black-hole is strong enough to (eventually) make a star exceed that rate, that is when it becomes 'invisible', the object is still there in some form (matter) and it may even still be emitting light.

No, that's not right. Not even a black hole can accelerate matter beyond light speed. A star approaching a black hole would get tidally ripped apart and sucked into it, never to be seen again.

Here is a better explanation of what's at that matter-antimatter link you gave.

 

[MHz]

If an object that emits light is traveling at the speed of light, how could light go in the opposite direction?
http://csep10.phys.utk.edu/astr162/lect/blackhole/blackhole.html
"Event Horizons

The event horizon is the point outside the black hole where the gravitational attraction becomes so strong that the escape velocity (the velocity at which an object would have to go to escape the gravitational field) equals the speed of light. Since according to the relativity theory no object can exceed the speed of light, that means that nothing, not even light, could escape the black hole once it is inside this distance from the center of the black hole. A more fundamental way of viewing this is that in a black hole the gravitational field is so intense that it bends space and time around itself so that inside the event horizon there are literally no paths in space and time that lead to the outside of the black hole: No matter what direction you went, you would find that your path led back to the center of the black hole, where the singularity is found."

I can understand why mass could not escape that kind of gravity, but light has no mass, how could gravity effect something that has no mass? It could pull a star apart, that would probably extinguish it's ability to produce light in the 1st place.
Here's another question I have, if the event horizon is some distance from the center and the speed of light is obtained at that distance then does gravity remain constant after that. Your example of the earth and a person (which I agree with) would point to the effect of gravity not being equal at any point.

Your link indicates that black holes are not always at the exact center. Galaxies are always 'on the move' in the universe. If one is moving from x to y, is the center of the black hole 'always' closer to the y side of the event horizon. The article doesn't cover that aspect, it only says they are off-set. The black hole would be the true direction and speed but matter on the opposite side of travel is just lagging behind a bit.

 

[Dexter Sinister]

...how could gravity effect something that has no mass?

Relativity doesn't view gravity as a force that acts on mass. The presence of mass changes the shape of spacetime around it, and anything moving through just follows the shortest path.

That article says the black hole is offset from the centre of the galaxy, not that the event horizon isn't symmetrical around it. I imagine a rapidly moving or accelerating black hole might see some stretching of the event horizon in certain directions, but I couldn't begin to calculate that.

 

[Tonington]

Bah, where's that dang Niflmir when you need him? Probably off hunting for some rare fungi or slaying some elite Warcraft character!

I remember a conversation we had a few weeks back touching on this subject, but alas I'm having problems consolidating the finer points. I seem to remember something about any blackhole produced at the LHC passing through the earth quickly, and without much consequence, but as I said, I'm having troubles remembering what it was he said. I think I'll email him to ask for a quick appearance to sate the curiosity on some of the points mentioned here, though Dexter has come through with his regular showing of stellar depth and guidance.

 

[MHz]

If a black hole can accelerate a light producing object to light-speed, and not beyond, if you were standing behind, it should 'disappear', that seems like speed is the factor and not gravity. Would you be able to see it if you were directly in front of it? It wouldn't seem so unless relative motion in that direction was not a factor. No matter what the speed of any object is, relative to it's surroundings, light going in the direction it is traveling would always be 186,000mi/sec faster than the object.
From a stationary point, the object is traveling at light speed towards that point, light emitted would be going twice the speed of light, relative to a fixed point.

A more graphical example of the same principle. Say you can view a galaxy from above so you have the best view of the way stars rotate around it's center. At a stationary distance it takes 1 hour to make 1 complete rotation. If you introduce some motion either away or towards you (and some optics that keep it the 'same size' in your field of vision) when it is going away from you that motion should 'appear to slow-down', one complete rotation taking more than 1 hour. If it was coming at you, that rotation should appear to speed up, 1 rotation taking less than 1 hour.
Say that happened at 1/2 the speed of light. What happens if motion is given to the observer, if traveling away (same kind of optics in place) that should make the object appear to be rotating even slower. What would happen to the view if speed was increased to more than 1/2 the speed of light, would it simple 'disappear'? On the other side, if the observer was traveling towards the galaxy, it's rotation should seem to speed up even more.
What happens to the view if that speed is more than 1/2 the speed of light, does it just get faster? How would you judge distance and time, neither object is moving faster than light, yet the rate of approach is faster than light. If a distance could be established you should have x hours to move out of the way, based on light speed, yet the actual time would be less than that if both were traveling at 3/4 light speed

I've tried several sites and they all say our universe is expanding (and most say gaining speed) but I can't find anybody who has put a number to the rate at which it is expanding.

 

[Dexter Sinister]

If a black hole can accelerate a light producing object to light-speed, ...

It can't. Nothing with mass can get to light speed, everything without mass has to go at exactly light speed, as far as we know. The speed of light is the same for all observers all the time, regardless of their state of motion or the state of motion of the light source. If something that's receding from you is accelerating, it'll always be visible, at least in principle, its velocity relative to you will never get to the speed of light. It won't "wink out" on you. Once in sight, always in sight.

I haven't thought your example of the galaxy moving along your line of sight all the way through, but from your perspective clocks in that galaxy will be running more slowly than yours, and since its rotation period provides a kind of clock, I'd expect it would appear to you to be turning more slowly the faster it's moving, in either direction. If it were moving across your line of sight, its shape would also change, appearing to shrink in the direction of motion. It'd take a pretty hefty relative velocity to make such effects noticeable, something over 40,000 km/sec to make a 1% difference in anything you can measure. And since galaxies actually rotate on a scale of one revolution in hundreds of millions of years--our solar system makes one orbit in about 225 million years, so it's made less than 2 dozen orbits in its lifetime--you'd be hard pressed to detect anything at all.

For the expansion rate of the universe, what you want is the Hubble Constant. Best current value I think is 71 km/sec per megaparsec if my memory is correct, plus or minus about 4%, which means for every million parsecs of distance from you, the recession velocity of whatever you can see increases by 71 km/sec. A parsec, a contraction of parallax-second, is about 3.26 lightyears. Hold your hand out at arms length and make a thumbs up sign. Look at your thumb with each eye alternately, while the other is closed, and notice how your thumb's position appears to shift against the background. That effect is parallax, and comes from viewing things from different angles, in this case the corners of an equilateral triangle whose base is the distance between your eyes and height is the distance to your thumb. A parsec is the distance at which something will appear to shift against the more distant background by one second of arc in observations made six months apart, from opposite sides of the earth's orbit.

 

[Kreskin]

Dexter, unless you're nearing your 300th birthday, how in hell did you ever find the time and brainpower to learn all this stuff? Holy cow I feel incredibly stupid (not hard to do) when I read your posts.

 

[talloola]

Dexter, unless you're nearing your 300th birthday, how in hell did you ever find the time and brainpower to learn all this stuff? Holy cow I feel incredibly stupid (not hard to do) when I read your posts.

I got the thumbs part Kreskin, did you?:smile:

 

[Niflmir]

Its funny how a thread presumably about high energy physics gets derailed into a discussion about black holes.

There are three points that make the black holes "producable" by the LHC not worrisome. The first is simply that there isn't really any widely accepted theories which predict them. The second point has to do with the fact that Hawking radiation would make them evaporate essentially immediately. Finally, given the difference in size between the micro black holes that are "predicted" and the Earth, or even our bodies, at most they would absorb an atom or two and then disappear.

As for wormholes and blackholes, there is a tentative connection that some people take to the extreme. For a long time people worried about the apparent singularity at the event horizon. After much research it was discovered that it was a coordinate singularity. By remapping the coordinates, it was shown that the Schwarzschild metric simply described one world sheet of a two world sheet universe. This was the first "wormhole", or as it was termed at the time, a Hawking-Ellis bridge. This other part of the universe has a very tenuous reality, as it is impossible to travel to.

 

[MHz]

It can't. Nothing with mass can get to light speed, everything without mass has to go at exactly light speed, as far as we know.

http://cosmology.berkeley.edu/Education/BHfaq.html
"You can think of the horizon as the place where the escape velocity equals the velocity of light. Outside of the horizon, the escape velocity is less than the speed of light, so if you fire your rockets hard enough, you can give yourself enough energy to get away. But if you find yourself inside the horizon, then no matter how powerful your rockets are, you can't escape."

According to the above, an object must be at the speed of light going into a black-hole, anything less would make escape possible. For something that is at the whim of gravity once that point is reached that's it.
Now say two light emitting objects that have a form of propulsion (say it is capable of 0.75 of light speed) on board, follows that same object, one has it's power (propulsion engines on all the time fighting against gravity) on all the time and the other turns it's power on at a certain point.
The object that has no power on would reach a point where it would no longer be visible, if max power was turned on an instant after it became invisible would it then become visible for even just a moment?
Would the object that has it's power on all the time have a different event horizon than an object that had no power, it's rate of descent would be slower by the amount of propulsion it was capable of.
The above doesn't take into consideration that a galaxy has rotation, so all those points, if they are considered to be equal would need to be at the same relative location to the observer.
From that observation point all matter is swirling around the black-hole as well as heading towards the hole itself. Say matter that is shedding light is moving away on one side (right) and coming towards the observer on the other side (left). Given the same distance from the horizon both should have equal velocity. From the point of the observer the right side should have a higher velocity (observed)because it is moving further away from the observation point. The one on the left should have a lower observed velocity because it is moving closer. Near the speed of light one side could exceed the speed of light because of the added velocity caused my it moving away from the observer. The other side would appear to be moving slower by that same amount. Wouldn't that effect also make it appear that the center of the black-hole is off to one side?

You also mentioned that you cannot see light because gravity has it trapped (rather than the speed of the object). Say your observation point is just a bit above the plane that most of the material is on (like a dinner plate). On the near side you can see the event horizon and then blackness after that point. Say the blackness is 1/4 of the diameter of the plate. Can you see the event horizon on the other side of the black-hole? From a low enough angle of observation (closeness to the plate) so that the other event horizon (straight line of sight) would be less than 1/2 the diameter of the hole. If light is affected by gravity you shouldn't be able to see the other side (light is sucked in), if light is not affected by gravity you should be able to see the other side that is the same distance from the center of the hole as you can on the near side.

The speed of light is the same for all observers all the time, regardless of their state of motion or the state of motion of the light source. If something that's receding from you is accelerating, it'll always be visible, at least in principle, its velocity relative to you will never get to the speed of light. It won't "wink out" on you. Once in sight, always in sight.

Just to make sure you got my general drift I'll get to a very simple explanation, for my benefit not yours.

A person is at point A, a straight goes both left (point B) and right (point C) from there. The line and points are stationary. A person looks from point A towards point B. A light source leaves point A going towards point B at 0.9 light speed. With some optics you zoom in as it moves away from you so it stays the same size in your vision. You should be able to see it forever. The light is traveling back to you from the object at light speed but it is not the same as it was when it was stationary at point A (color shift if nothing else). With neither the observe nor the light source moving it is reaching the observer at light speed (white light). What happens if the observer starts heading towards point C at 0.9 light speed (opposite direction than the light source took off in) The combined speed away from each other is 1.8 light speed. This is where I fail to (pun intended) to see the light. No light is coming from point A the only light on is from the object headed towards point B.
Now time could be introduced, same as my previous example, say there was a marker on the light and the light rotated once/minute by the watch the observer held. Once the lighted object started to move that rotation of the object would not change for the object no matter what change in the speed that was separating the two. But would there be an apparent change in that rotation from the observers POV?

I hate repeating myself I just want to make sure you understand what I'm trying to describe.

I haven't thought your example of the galaxy moving along your line of sight all the way through, but from your perspective clocks in that galaxy will be running more slowly than yours, and since its rotation period provides a kind of clock, I'd expect it would appear to you to be turning more slowly the faster it's moving, in either direction. If it were moving across your line of sight, its shape would also change, appearing to shrink in the direction of motion. It'd take a pretty hefty relative velocity to make such effects noticeable, something over 40,000 km/sec to make a 1% difference in anything you can measure. And since galaxies actually rotate on a scale of one revolution in hundreds of millions of years--our solar system makes one orbit in about 225 million years, so it's made less than 2 dozen orbits in its lifetime--you'd be hard pressed to detect anything at all.

That's why I made the numbers so small. In the link in this post they explain about escape velocity. If that is applied to the big-bang then as soon as initial velocity is achieved (leaves the hand) things should start slowing down. Gravity between celestial bodies should have the same effect. The universe is still accelerating, so we are either the apple that is still in the hand (not released yet) or we have have escaped earth's gravity (slowest velocity) and (if tossed in the direction of the moon) if we are picking up speed then we are being pulled towards something.

For the expansion rate of the universe, what you want is the Hubble Constant. Best current value I think is 71 km/sec per megaparsec if my memory is correct, plus or minus about 4%, which means for every million parsecs of distance from you, the recession velocity of whatever you can see increases by 71 km/sec. A parsec, a contraction of parallax-second, is about 3.26 lightyears. Hold your hand out at arms length and make a thumbs up sign. Look at your thumb with each eye alternately, while the other is closed, and notice how your thumb's position appears to shift against the background. That effect is parallax, and comes from viewing things from different angles, in this case the corners of an equilateral triangle whose base is the distance between your eyes and height is the distance to your thumb. A parsec is the distance at which something will appear to shift against the more distant background by one second of arc in observations made six months apart, from opposite sides of the earth's orbit.

I was hoping to find a number that is in % of a light years from any galaxy that is headed in the opposite direction, I could then divide that by 2 to get how fast our world is heading away from where the big bang took place. Then the rate of acceleration could be applied but that part of the question I was forming isn't necessary
at this early stage. I don't have any mass or distance numbers for any object that might be pulling us towards it.
It would be interesting to know if all parts of our universe (ball form) is accelerating at the same rate. If one portion is accelerating faster than another then an object is more likely to be in that direction.

One last thought, if matter (only thing that can cast it's own light or reflect light from another source) cannot obtain true light speed then is a black-hole truly black? Couldn't a tiny portion escape but it appears black because of the brightness of the light matter is shedding just before the event horizon. If you cup your hands over your eyes and keep your eyes open it will appear black at first, once your eyes become accustomed (say 5 min) it is no longer totally black as it will tend to be a dark blue-gray, for my eyes anyway another person might have a slightly different color depending on if there are any differences in color vision normally.

 

[MHz]

Its funny how a thread presumably about high energy physics gets derailed into a discussion about black holes.

There are three points that make the black holes "producable" by the LHC not worrisome. The first is simply that there isn't really any widely accepted theories which predict them. The second point has to do with the fact that Hawking radiation would make them evaporate essentially immediately. Finally, given the difference in size between the micro black holes that are "predicted" and the Earth, or even our bodies, at most they would absorb an atom or two and then disappear.

To get back on track, a bit anyway. What practical application does this have?
Whatever it cost, it doesn't sound cheap. Why do I get the feeling that the cost is eventually picked up by the average tax-payer? From a personal POV those black-holes that I hit on some neglected road while driving at night are more important (in a real life situation) than this experiment.

 

[Dexter Sinister]

Dexter, unless you're nearing your 300th birthday, how in hell did you ever find the time and brainpower to learn all this stuff?

Actually, it's all perfectly simple, you too can appear to know far more than you actually do. :smile: All you need is the basic understanding, a knowledge of how to use Google, a couple of good reference books near at hand, a browser that'll display multiple windows or tabs, and a wide screen monitor and a big desk so you can see everything at once. And take your time composing a post.

 

[Praxius]

You keep saying 'other side', as if talking about worm holes rather than black holes Prax. I was always told there is no 'other side' with black holes, no?

If energy is always constant, then it can not be destroyed, therefore that energy must go somewhere. Just because you might be ripped to shreds and have no possible chance of survival as we know it when you go through the Event Horizon, doesn't mean all that matter doesn't still go somewhere or turn into something.

And they tell us there is no other side to black holes.... but:

"While general relativity describes a black hole as a region of empty space with a pointlike singularity at the center and an event horizon at the outer edge, the description changes when the effects of quantum mechanics are taken into account. Research on this subject indicates that, rather than holding captured matter forever, black holes may slowly leak a form of thermal energy called Hawking radiation. However, the final, correct description of black holes, requiring a theory of quantum gravity, is unknown."

It's all still theory at this point and seems to be based on scientific observations without tangible evidence, so it's anybody's guess at this point.

"In physics, a wormhole is a hypothetical topological feature of spacetime that is basically a 'shortcut' through space and time. A wormhole has at least two mouths which are connected to a single throat or tube. If the wormhole is traversable, matter can 'travel' from one mouth to the other by passing through the throat. While there is no observational evidence for wormholes, spacetimes containing wormholes are known to be valid solutions in general relativity."

One is a theory on a hole which can take you to point A to point B in a different time frame/speed in the known universe.... the other is unknown.... well both are unknown actually, but the concepts are different, yet similar.

 

[Praxius]

There is, in a sense, it's called inertia, but it's easier to describe the other way around. The acceleration is less at the top than at the bottom, so your feet will gain velocity faster than your head, and if the difference is large enough it'll pull you apart. Under normal circumstances, like standing on the earth for instance, the difference in the force of gravity between your feet and your head is pretty small, but it's there. It diminishes as the inverse square of the distance, as measured from the centre of the earth. The distance between your feet and your head is such a tiny fraction of that that it makes no sensible difference, but in a hugely stronger field, it will.

But in space, gravity for the most part is zero... there is no major resistence, and if I push you, we both move away and just keep on going. Therefore, if the event horizon pulls you in, to me, it makes sense that it's be just like dipping your foot in a strong river current which would suck you along. There is resistence here on earth when considdering the river idea, but how much resistence is there in space to cause this massive pulling effect that may kill you? No wind resistence, no gravity from a planet nearby.... granted when you are thrown at a high speed from this effect, there's chances that you'd get shredded by high speed traveling space dust or something (like a bullet to the head) but other then that, seems all clouded to me.

*shrugs*

 

[Kreskin]

Actually, it's all perfectly simple, you too can appear to know far more than you actually do. :smile: All you need is the basic understanding, a knowledge of how to use Google, a couple of good reference books near at hand, a browser that'll display multiple windows or tabs, and a wide screen monitor and a big desk so you can see everything at once. And take your time composing a post.

Would staying at a Holiday Inn Express help me?