Astrophysics and Cosmology - Discuss the Universe here

[Value Of Pi]

That's ok Chronaut.  I was just trying to stump you.     
so now I have to look up another ten words and go back to the library.  I really appreciate your answer.  It might take me a while to comprehend what you said.

Stump him? Ha! Get yourself to the library and look up those words. That'll teach you to try stumping Chronaut. The man really seems to know his stuff (not that I have the background and knowledge to tell for sure) and we are lucky to have him. But please, let's try and keep the questions and answers as simple and unconfusing as possible, for the benefit of all the liberal arts majors who might wander in here.

[Agent : Orange]

I haven't read it yet, but this is not entirely hypothetical.  Some small organisms on Earth are dominated by things like surface tension of fluids and electrostatic charge.  Unfortunately they can't tell us that that feels like.

Yes it's true. These organisms would have a very different understanding of the cosmos than we would even if they could observe the outside world.

That paper also contains a great example of the size of the beings they consider. A caption reads "Above: They are very tiny" below a blank figure. Effective.

[GravitySucks]

Stump him? Ha! Get yourself to the library and look up those words. That'll teach you to try stumping Chronaut. The man really seems to know his stuff (not that I have the background and knowledge to tell for sure) and we are lucky to have him. But please, let's try and keep the questions and answers as simple and unconfusing as possible, for the benefit of all the liberal arts majors who might wander in here.

Yeah, what ever happened to "Its intuitively obvious to the most casual observer. "

[Agent : Orange]

Yeah, what ever happened to "Its intuitively obvious to the most casual observer. "

"It is left as an exercise for the reader to prove the effect occurs as stated."

[area51drone]

It may not be truly singular at the center due to quantum gravity hijinx. A black hole has an event horizon, a neutron star does not. That means a black hole does not emit any radiation. Black holes are consistent with microlensing observations which set strong limits on the flux that can be coming from that object. All we can say about the mass inside the horizon is that it is sufficiently compact to have an event horizon so can't have any external structure and since we know about the type of degenerate pressure that can be generated by matter we don't know of anything that could form structure inside the horizon.

I don't find it odd that more mass increases the event horizon, since that's predicted by GR. It's spacetime curvature that makes up the external gravitational field, and you can think of Einstein's field equations as telling you how to translate mass into spacetime curvature. That's totally consistent.

If you're uncomfortable with the concept of an event horizon you're always free to transform to a frame where it doesn't exist and do your calculations there instead. Nothing wrong with taking the falling astronauts point of view.

Edited to add: Let me also say for completion that not all black holes have singular points - the rotating black hole solution (called the Kerr solution) has a singular ring.

You wouldn't say, that in a way, every large body has an event horizon where you cannot escape it's gravity (ignoring the ability to generate opposing forces, or coming at it with speed)?   Of course, a black hole is not a star, but what concrete example says that what is inside of a black hole is not simply matter in some form that does take up a reasonable amount of space?   So far all you've given examples of are the outside observations and calculations, which you admit DO break down at the singularity.   You don't know what happens even beyond the point where someone has gone from red to dark red to invisible.

In the ring case, is the singular ring a 2d ring or a ring rotated in 3 space, such that it makes a hollow sphere?

[Agent : Orange]

You wouldn't say, that in a way, every large body has an event horizon where you cannot escape it's gravity (ignoring the ability to generate opposing forces, or coming at it with speed)?   Of course, a black hole is not a star, but what concrete example says that what is inside of a black hole is not simply matter in some form that does take up a reasonable amount of space?   

An event horizon is not a physical thing. It's a radius at which the escape velocity is equal to the speed of light.
Every body has an event horizon, it is the radius beyond which the body would need to be compressed to become a black hole. You have an event horizon smaller than a proton. If you were crushed to this radius your body would be entirely within the event horizon and your matter would have sufficient density to become a black hole. In fact, in all stellar modeling schemes you have to check if the radius is smaller than the event horizon defined by the interior mass at all radii inside the star. That's the difference between a star and a black hole a star has a surface which by definition is outside of the event horizon. A black hole has all mass within the event horizon.

So far all you've given examples of are the outside observations and calculations,

Which are all we'll ever have. No signals can get out.

which you admit DO break down at the singularity. 

They do, but that does not affect the horizon structure or the external geometry. Newtonian gravity breaks down at r=0 too, and so do Maxwell's laws. It's why the delta function was invented/discovered.

You don't know what happens even beyond the point where someone has gone from red to dark red to invisible.

Yes, I do. Everything up to the singularity is well defined and understood mathematically. The singularity is not. The outside observations agree with GR predictions. No matter how much you may dislike it, GR has a track record of working well and it does in this case too. It has a long line up of people hoping and praying to shoot it down and would not have lasted as long as it has if it did not work well. Everyone wants to be the guy to beat Einstein but it's proven very difficult to do.

Edited to add: Of course, GR is not the full picture, which would also give back the behavior of mass and density at the singularity. But any theory that replaces it pretty much has to keep all the stuff that GR does right in terms of the external and horizon geometry. It will "reduce" to GR in the appropriate limit. It *must* because GR matches so well with what we observe. There's not really any way around that.

In the ring case, is the singular ring a 2d ring or a ring rotated in 3 space, such that it makes a hollow sphere?

It's a 2D ring in the plane of rotation. There's a more complicated horizon structure, too.

[area51drone]

Yes, I do. Everything up to the singularity is well defined and understood mathematically. The singularity is not. The outside observations agree with GR predictions. No matter how much you may dislike it, GR has a track record of working well and it does in this case too. It has a long line up of people hoping and praying to shoot it down and would not have lasted as long as it has if it did not work well. Everyone wants to be the guy to beat Einstein but it's proven very difficult to do.

I've got more to say but I need to go do something so I'll just keep the conversation flowing with this..  I don't dislike GR, I'm simply asking is there any physical evidence that there can't be a body inside the event horizon?  You say no, but only give a model, which GR is, even though at least from all past experiments it has been proven to be true.  But it's still a model.   I'm asking you, is there anything physical, an experiment that has been done, might be able to be done (even in theory), or an observation of a distant body that proves beyond a shadow of a doubt that the mass is not a singular point (or ring, or whatever).   How can one say that GR is correct beyond the point we can see when there is no data to prove it?   Again, I'm not trying to ask this in a gotcha kind of way.    I just don't understand how mass/energy can fall to a single point in space.   I'm not saying I can't understand why according to GR, I certainly could if I just accept that it is true everywhere (like you do), I just find it physically hard to believe because a singularity that is infinite seems like adding infinity+10 more stars shouldn't grow the event horizon, yet apparently it does.  Do you see what I'm saying?   

[Agent : Orange]

I've got more to say but I need to go do something so I'll just keep the conversation flowing with this..  I don't dislike GR, I'm simply asking is there any physical evidence that there can't be a body inside the event horizon? 

From what we understand about compressibility and the pressure-density relationship of matter under extreme circumstances we don't know of anything that can stand up to the extreme gravity inside. It should all be very nearly pointlike. Please don't get me wrong, that's by no means the whole story, surely there are quantum effects that are important at the singularity. The current thinking is that these will smooth out the singularity to prevent an infinity there. Many people also have other ideas about what might be in there from string theory also. But again, the horizon and external geometries reduce to GR within the observational error margins, as they must, for all these models.

You say no, but only give a model, which GR is, even though at least from all past experiments it has been proven to be true.  But it's still a model.   I'm asking you, is there anything physical, an experiment that has been done, might be able to be done (even in theory), or an observation of a distant body that proves beyond a shadow of a doubt that the mass is not a singular point (or ring, or whatever).   

You can get it from the Hawking radiation and gravitational waves will tell you a lot about whether or not there's a structure in there too given how black holes merge and ringdown. But there are other physical reasons why the mass has to be very localised to a small region near the center which is to do with our understanding of the properties of matter.

How can one say that GR is correct beyond the point we can see when there is no data to prove it?   Again, I'm not trying to ask this in a gotcha kind of way.    I just don't understand how mass/energy can fall to a single point in space.   

The least speculative option is GR given how well the other predictions all stand up to scrutiny. And thats my argument, given the success of GR anything that comes afterward has to reduce to GR in the appropriate limit, just like GR reproduces Newtonian mechanics in the appropriate limit. So it may be there's a spacetime crystal or phase transition to another universe inside a black hole or some other exotic thing. Observers are limited to what they can measure about black holes so we would have to hope that subtle distinctions exist between these options to distinguish the new theories predictions from vanilla GR, ie in the gravitational wave signature or some details of the black hole shadow, etc. These are quantities which are now on the cusp of being tested. Exciting times!

I'm not saying I can't understand why according to GR, I certainly could if I just accept that it is true everywhere (like you do), I just find it physically hard to believe because a singularity that is infinite seems like adding infinity+10 more stars shouldn't grow the event horizon, yet apparently it does.  Do you see what I'm saying?

Why should adding mass to a black hole NOT grow the event horizon? More mass means more curvature which means it's more difficult to escape the black hole at larger radii. I don't understand your objection to this point.

radius of event horizon = 2GM/c^2 where G is the gravitational constant, c the speed of light and M mass of the black hole. As M goes up, the radius of the event horizon goes up too.

Edited to add: I re-read your post and think you are mistaking mass for mass-density. The mass of the black hole is finite so M has a well-defined finite value. That mass must all be in a very small (point-like) region at the center of the black hole. This since mass divided by volume gives mass density if that mass is in an extremely small volume the mass density is very high. That mass density is what is finite, not the mass itself at r=0. Hope that helps.

[GravitySucks]

That last part was intuitively obvious to me... Hence some black holes are "bigger" then others and they should continue to "grow" as long as there is matter to be drawn into them by their graviton all force. As they grow in mass, the event horizon should grow as well. 

[area51drone]

I reread my statement and yes I agree I was confusing mass with mass density.   I do know the difference, I don't know why exactly I said that.   

Hawking radiation and gravitational waves will tell you a lot about whether or not there's a structure in there too given how black holes merge and ringdown.

How's that?

So it may be there's a spacetime crystal

[FearBoysWithBugs]

So it may be there's a spacetime crystal

Some guy in the Tenderloin was trying to sell me some crystal last weekend.  I know that some of these physics geniuses are idiosyncratic and don't pay too much attention to their grooming or hygiene, but this guy looked like a drug addict and not a physicist, so I passed.  Had no idea he was offering me a pathway to another universe.  He only talked about it taking me to the moon.

I wonder if he's still trying to sell that thing.  BRB guys, imma check it out.

[Agent : Orange]

I reread my statement and yes I agree I was confusing mass with mass density.   I do know the difference, I don't know why exactly I said that.   

How's that?

The details of how a newly formed black hole relaxes after a merger will have a lot to do with the structure of the horizon would presumably be influenced by internal structure if any existed. Which again, it doesn't to the best of our understanding. See also the event horizon telescope, http://www.eventhorizontelescope.org/science/general_relativity.html

[Agent : Orange]

Some guy in the Tenderloin was trying to sell me some crystal last weekend.  I know that some of these physics geniuses are idiosyncratic and don't pay too much attention to their grooming or hygiene, but this guy looked like a drug addict and not a physicist, so I passed.  Had no idea he was offering me a pathway to another universe.  He only talked about it taking me to the moon.

I wonder if he's still trying to sell that thing.  BRB guys, imma check it out.

Make sure you get the blue spacetime crystal.

[Camazotz Automat]

Make sure you get the blue spacetime crystal.

Yes.  Make certain it's Heisenberg.

[FearBoysWithBugs]

Make sure you get the blue spacetime crystal.

Awwww, man!!   I got the plaid one!  Why dint you say something before, man?

What am I gonna do with this thing.  It tastes like rock candy and newspaper.

[Chronaut]

Chronaut, before I forget let me say thanks for posting this. In fact, we have a weekly journal club at work where we talk about interesting papers we've come across and I put this one on my stack. So when I saw the link it reminded me of another really interesting one that I think many people here may also find interesting.

This paper was posted in November 2015, it is a physics paper but only contains some light basic equations in the text and really stood out for me and captured my imagination. The paper is called "atomic beings and the discovery of gravity", and the general idea is to explore how difficult it would be for a civilization of tiny microscopic people to discover the force of gravity, since they would be so overwhelmed by electromagnetic phenomena in their day to day (which are fractions of a second to us) lives. The paper goes on to speculate that the nature of gravity might forever be obscured to such a civilization, with the beings coming up with more elaborate charge distributions needed to describe the universe, culminating in their theory of "dark charge"!
The analogy to our current situation in cosmology is that maybe some of our big conceptual problems come from seeing only a small corner of a much larger picture.
Was a really neat read. And can be found here:
http://arxiv.org/abs/1511.05431

I'm glad you found that interesting Agent : Orange - the thought of an experimental gravitational field generator is so exciting that I don't even care how much it would cost; it would be worth it.  And you just never now what kinds of breakthroughs will come out of that kind of effort.

That paper sounds like a blast, and the meandering arrival of the Atom People's physical science to a theory of "dark charge" is fascinating.  I'm actually sympathetic to the notion of additional forces at cosmological scales, which isn't something I generally speak of in polite company, so it'll be interesting to see if this offers an approach to proving such a thing.  I'm hoping that higher resolution analyses of dark energy will reveal a mechanism more useful than the dreaded cosmological constant, which seems like a placeholder.  But then again I feel the same way about most if not all of the constants - someday I expect to see derivations; probably once we have a fully unified field theory.

Stump him? Ha! Get yourself to the library and look up those words. That'll teach you to try stumping Chronaut. The man really seems to know his stuff (not that I have the background and knowledge to tell for sure) and we are lucky to have him. But please, let's try and keep the questions and answers as simple and unconfusing as possible, for the benefit of all the liberal arts majors who might wander in here.

I'm with Feynman on this one - if you really understand something clearly, you should be able to explain it to any intelligent listener.  That gets to be a real problem with quantum mechanics, for everybody actually, which is one of the reasons I constantly wonder if there's a better underlying theory that we just haven't discovered yet.  The math works brilliantly, but even the world's leading experts have trouble explaining it.

And I can offer some good tidbits here and there because I love to dig into weird stuff, but honestly Agent : Orange is a better scientist than most of the pros I see at the main physics boards - he's got the academic foundation for mainstream teaching, but he's also got that rare passion for global interdisciplinary insights that open up new doors to deeper levels of understanding.  You're lucky to have him on such a small board.  Perhaps it's because there's such a disproportionate representation of seasoned engineers, technicians and investigators around here to keep things fun and lively.

Of course, a black hole is not a star, but what concrete example says that what is inside of a black hole is not simply matter in some form that does take up a reasonable amount of space?

I can offer two answers to this question; the first is the sound but kinda boring answer, the second is speculation but perhaps more interesting.

The gravitational wave signal that we got this month confirms the mathematical model that we have for black hole structure and collisions - so we know that our understanding of black holes is pretty darn well right on the money.  Because the gravitational waves give us information about what's going inside the event horizon as the singularities spiral together, merge, and ringdown like a bell.  The shape of the wave we saw fit within the expected parameters of predictions - that's quite an accomplishment, considering that we've had to infer everything we know about these objects.

On the other hand, the resolution of the LIGO facilities can and will be improved, and we can only currently detect a limited range of frequencies of gravitational radiation, so we can't see every last detail of what happened when those black holes merged.  Now perhaps Agent : Orange has the mathematical chops with quantum chromodynamics to answer this question decisively, but it seems plausible to me that there could be some kind of Pauli-exclusion-like principle with quarks that would prevent the matter of the singularity from forming a true point, or two-dimensional ring.  It just strikes me as deeply counterintuitive to presume that a nonrotating singularity would have no volume whatsoever.  I think at this point it's possible that the singularities that we recently heard merge into one, could have been very small but still 3D objects - perhaps the size of a proton or smaller.  It'll be interesting to see what comes out of the on-going analysis of the signal, and the confidence level of mathematical predictions about the singularities.

In any case, the exciting thing about gravitational waves is that it should be possible to answer this question decisively, observationally, someday.  With sufficiently sensitive gravitational wave detectors, we should be able to tease a Lot of new data about black holes from the waveforms we detect when black holes collide, right down to the precise properties of the singularities.  If they have any physical volume, we'll be able to see it sooner or later because they'd oscillate upon collision like a drop of water (but ostensibly at outlandishly high frequencies, given their ~infinite density).

In time we should also be able to gather detailed observational information about the first trillionths of a second into the Big Bang, or better.  And gravitational waves could help us answer one of the most important open questions in modern cosmology: "what drove the inflationary expansion?"

This is the one aspect of Hawking Radiation that I never had a firm understanding of.

This is one of the hairiest questions in theoretical physics, and I'm not sure if anyone genuinely has a firm conceptual grasp of it even though the math works out.  Even John Baez seems to struggle with it - have a look at some of the forms of the explanation offered here:
http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/hawking.html

What is clear is that black holes are predicted to emit black body radiation - a nice smooth statistical distribution of frequencies of energy - so the big celestial-scale black holes we usually think of are only emitting photons, which are also their own antiparticle.  Small black holes are hotter - they can even glow like a star.  And those hot black holes emit photons and particles and antiparticles.  Apparently the energy to make these particles is at first briefly borrowed from the quantum vacuum fluctuations, and then that energy debt gets absorbed by the black hole as the particles climb out of the black hole's gravity well.  Somewhere I read that the energy to make the Hawking radiation comes from the black hole's gravitational potential energy field, which seems weird, because Hawking talks about the gravitational field as a manifestation of negative energy rather than positive energy.  Which begs the question: how does stealing negative gravitational energy create a positive mass particle?

This excerpt may give you some idea about the rather messy theoretical situation surrounding Hawking radiation - so if you find it frustrating and unclear, you're in good company:

"This paper explains the nature of the difficulties, and reviews the proposals that have been put forward to deal with them. None of the proposals put forward can so far be considered to be really successful, and simple dimensional arguments show that quantum-gravitational effects might well alter the evaporation process outlined by Hawking. Thus a definitive theoretical treatment will require an understanding of quantum gravity in at least some regimes. Until then, no compelling theoretical case for or against radiation by black holes is likely to be made. "

"Do black holes radiate?" Adam D. Helfer, 2003
http://xxx.lanl.gov/abs/gr-qc/0304042

[zeebo]

I wonder if this idea might help others get why black holes are black.  I heard this recently and it made sense to me. 

See objects of significant gravity, like say planets or stars, have what's called 'escape velocity'.  This is how fast you must go to break far enough away to avoid being sucked back in to said gravitational source. For instance the Earth's is around 25,000 mph. 

A black hole however is so dense that it's escape velocity is faster than the speed of light, which is impossible to ever do, as Einstein proved.  Sorry, photons. 

[Chronaut]

I wonder if this idea might help others get why black holes are black.  I heard this recently and it made sense to me. 

See objects of significant gravity, like say planets or stars, have what's called 'escape velocity'.  This is how fast you must go to break far enough away to avoid being sucked back in to said gravitational source. For instance the Earth's is around 25,000 mph. 

A black hole however is so dense that it's escape velocity is faster than the speed of light, which is impossible to ever do, as Einstein proved.  Sorry, photons.

That's right.  The light/photons actually orbit around the black hole outside of the event horizon because they can't escape, in a region called the "photon sphere":

https://en.wikipedia.org/wiki/Photon_sphere

[area51drone]

I think at this point it's possible that the singularities that we recently heard merge into one, could have been very small but still 3D objects - perhaps the size of a proton or smaller.  It'll be interesting to see what comes out of the on-going analysis of the signal, and the confidence level of mathematical predictions about the singularities.

I don't know if I'm using the right terminology here, but can one of you explain how a large mass can collapse to a single point in terms of a quantum field?   As AO expressed early on in this thread, we should really think of everything in terms of fields.   Mass, as far as I understand, is just a fluctuation in this field, when great enough there is quanta that becomes say a proton (or a quark whatever). 
In 2D terms, I think of an oscilloscope, and maybe this is the wrong way to think about it, but let's say you have a particle (a bit of mass) when the scope reads 5 volts at a wave crest.   Is that a fair, albeit overly simplistic analogy?  In that example, would a lot of mass close together be a higher frequency in the field?   

I have another question for you Chron, as it relates to Bob Lazar.  Do you recall his comments about the candle flame?   What do you think about what he said in terms of his claims of a gravity generator?  What brings this question to mind is this:

http://www.skyandtelescope.com/astronomy-resources/time-changed-inside-a-black-hole/

Time comes to a standstill at the event horizon, such that an outside observer will never really see anything fall inside a black hole. Strangely enough, this even includes the surface of the star that collapsed to form the black hole!

[Chronaut]

I don't know if I'm using the right terminology here, but can one of you explain how a large mass can collapse to a single point in terms of a quantum field?   As AO expressed early on in this thread, we should really think of everything in terms of fields.   Mass, as far as I understand, is just a fluctuation in this field, when great enough there is quanta that becomes say a proton (or a quark whatever). 
In 2D terms, I think of an oscilloscope, and maybe this is the wrong way to think about it, but let's say you have a particle (a bit of mass) when the scope reads 5 volts at a wave crest.   Is that a fair, albeit overly simplistic analogy?  In that example, would a lot of mass close together be a higher frequency in the field? 

Some of this is pretty good, but our current model is a little more complicated than your description.  Quantum field theory describes photons as excitations in an underlying electromagnetic field, where the energy is proportional to the frequency:  smaller waves have more energy than bigger waves.  But each type of quark has its own quantum field, and electrons have their own quantum field.  And then there’s the Higgs field which gives the quarks mass.  We don’t have a quantum field theory for gravity yet. 

Oddly, it appears that most of the mass of a proton is in the kinetic energy of the quarks and the enormous binding energy of the gluons they swap back and forth constantly.

In concept a singularity would be a point-like excitation in all of the quantum fields.  It’s not so far-fetched when you consider that an electron has mass, and it’s point-like.  But we don’t really know what quantum rules apply to matter under black hole singularity conditions; I think a lot of physicists suspect that a true point-like singularity is unlikely, but the ultimate arbiter will be the data.

I have another question for you Chron, as it relates to Bob Lazar.  Do you recall his comments about the candle flame?   What do you think about what he said in terms of his claims of a gravity generator?  What brings this question to mind is this:

http://www.skyandtelescope.com/astronomy-resources/time-changed-inside-a-black-hole/

I’ve always thought that candle story was one of the biggest problems with Bob Lazar’s cover story.  Because for one thing, the reactor isn’t containing the gravitational field if it can time dilate a candle outside of it, but more crucially, time and frequency are dependent on each other, so if the candle became time dilated close to a standstill as he describes, the frequency of its light should be deeply red-shifted, and it would be much fainter.  It makes no sense to have a region of slowed time without changing the color or intensity of the light emitted from it.  Unless it's not a time effect at all, but some kind of acoustical standing wave effect holding the air in that region very still...that's just speculation though.

But again, I think that all of Lazar’s stuff about ufos and the gravity generator etc, is just cover story, fiction:  a fanciful tale to capture the public’s imagination so that the real “payload” of information â€" the military’s interest in funding superheavy element research, would get out to budget committees and other compartmentalized black budget programs.  With his actual background, which we know from a slew of public records, a guy like Lazar couldn’t get a job as a janitor at Area 51 or S-4, imo.  But he could certainly get a job as cut-out: a non-government shill employed to tell a story.

[Agent : Orange]

I don't know if I'm using the right terminology here, but can one of you explain how a large mass can collapse to a single point in terms of a quantum field?   

Well that's the exact problem that quantum gravity grapples with, singularities make problems for the uncertainty relation because they have an exact position. Funny things will happen when you approach them and it's not at all clear what they mean for quantum mechanics. That's why you need quantum gravity. All we can say classically is about the parts we can observe, shadow, etc. And as Chronaut rightly points out, the ringdown which is the key to this question. No one knows if you can put a whole stars mass into the volume of a quark. Unsatisfying. But it's a mystery. That's also the problem with the big bang, too, and why we can get right back on the fringes of t=0, because a similar problem happens there.

As AO expressed early on in this thread, we should really think of everything in terms of fields.   Mass, as far as I understand, is just a fluctuation in this field, when great enough there is quanta that becomes say a proton (or a quark whatever). 
In 2D terms, I think of an oscilloscope, and maybe this is the wrong way to think about it, but let's say you have a particle (a bit of mass) when the scope reads 5 volts at a wave crest.   Is that a fair, albeit overly simplistic analogy?  In that example, would a lot of mass close together be a higher frequency in the field?   

A big red flag of caution goes up here. It's really hard to make these kind of mechanistic analogies, you're getting into the region where it's difficult to really understand what's going on without doing some math. So our discussion with analogies can only really go so far. Quantum mechanics is counter-intuitive and the english that works to describe one case may fail in another.

The best I can say is that the wave that accompanies a particle is a wave of probability, and that you're more likely to detect a particle of mass m at a crest of the wave rather than a trough. Somewhere in that wave we could detect a particle. And, you can also think of the wave properties as depending on the momentum (or energy if you like), the wavelength and particle momentum are inversely related to one another. Anyway that's why it's hard to tell what the position of the particle is.

And, that's what's going to make all the problems for black hole singularities, if that's where you're going. We can't really sew the spacetime curvature and wave-function descriptions together, we really don't know how. GR lets us describe a black hole classically but when you start asking "what's the wave function of a black hole" you're up against a wall because there's no good answers and a lot of speculation. So my answer is: wait and see.

Anyway that discussion of wave and particle properties is the basis for the double slit experiment, and Feynman said that's all you need to understand quantum mechanics. So maybe it's a good place to start for black holes too.

[(Sandman) Logan-5]

Hi guys, cool thread.
Here's one for the catastrophists amongst us. It's a catalog of meteor impacts from ancient times to present including the recent up-tick in activity.  It contains some interesting insights into Roman and English culture too. Long article but good documentation and further links.
Enjoy.

http://www.sott.net/article/151954-Meteorites-Asteroids-and-Comets-Damages-Disasters-Injuries-Deaths-and-Very-Close-Calls

P.S. - There is also an article there about Project Blue Beam.

[FearBoysWithBugs]

Agent : Orange is a better scientist than most of the pros I see at the main physics boards - he's got the academic foundation for mainstream teaching, but he's also got that rare passion for global interdisciplinary insights that open up new doors to deeper levels of understanding.  You're lucky to have him on such a small board. 

All that may be true, but just try to get his help when buying a spacetime crystal from some dude in the Tenderloin.  Where's your god now?  A real letdown, I am sorry to say.

[Agent : Orange]

Now perhaps Agent : Orange has the mathematical chops with quantum chromodynamics to answer this question decisively, but it seems plausible to me that there could be some kind of Pauli-exclusion-like principle with quarks that would prevent the matter of the singularity from forming a true point, or two-dimensional ring.

Thanks for your kind words Chronaut. While quark degeneracy can't prevent a black hole, but a lot of people in the field speculate that quark stars may be an intermediate step between neutron star and black hole. There are a lot of interesting ideas out there about the types of supernovae that these would result in and other predictions regarding supernova remnants. There is also a wide gulf between our understanding of all the different kinds of neutron stars that we see out there, particularly in terms of their outburst and flaring activity.

Sad to say chromodynamics is far afield for me, but I do know how to use the results of nuclear many body simulations other people have done to make neutron star models from the equation of state.

[area51drone]

I’ve always thought that candle story was one of the biggest problems with Bob Lazar’s cover story.  Because for one thing, the reactor isn’t containing the gravitational field if it can time dilate a candle outside of it, but more crucially, time and frequency are dependent on each other, so if the candle became time dilated close to a standstill as he describes, the frequency of its light should be deeply red-shifted, and it would be much fainter.  It makes no sense to have a region of slowed time without changing the color or intensity of the light emitted from it.  Unless it's not a time effect at all, but some kind of acoustical standing wave effect holding the air in that region very still...that's just speculation though.

I'd love to see a video/animated gif of what a candle would look like to an outside observer if it were suspended in an increasing gravity field.   Get on that shit, boys.

You say there is no chance it wouldn't be color shifted, but by how much?  What happens once the photons reach the regular gravity field of earth and return to near the speed of light (in a vaccuum)?   Why wouldn't they shift back since they are then increasing in speed?    I know there was an experiment where someone "stopped" or slowed light significantly down in a medium.   What happened to the color of that light when was released?  Hoping you are familiar with that experiment...

[Chronaut]

All that may be true, but just try to get his help when buying a spacetime crystal from some dude in the Tenderloin.

Haha...I  tried bartering for some dilithium crystal down there and the savages stonewalled me; so now I have to construct an antimatter regulator using stone knives and bearskins.

I'd love to see a video/animated gif of what a candle would look like to an outside observer if it were suspended in an increasing gravity field.   Get on that shit, boys.

You say there is no chance it wouldn't be color shifted, but by how much?  What happens once the photons reach the regular gravity field of earth and return to near the speed of light (in a vaccuum)?   Why wouldn't they shift back since they are then increasing in speed?    I know there was an experiment where someone "stopped" or slowed light significantly down in a medium.   What happened to the color of that light when was released?  Hoping you are familiar with that experiment...

A candle seen from outside a gravitational field would just look Doppler shifted - redder and dimmer...and a strong enough field would also create a visible gravitational lens.  All of those effects would come into play as time approached a stop at the center of the field, at which point the candle would disappear completely from view.  The time dilation and the gravitational redshift are proportional, and dependent on the intensity of the field.

In free space, and the air is pretty close to free space for this consideration, the speed of light is constant.  Gravity just shifts the frequency of light, not the speed.  You can think of the photons (for example a blue photon) losing energy to escape the gravity well, so it drops in frequency as it climbs out of the well toward your eye, arriving at your retina red-shifted.

Your last part refers to "slow light" experiments in various media, but that's an unrelated phenomenon requiring special mediums and/or waveguides for the light to pass through:
https://en.wikipedia.org/wiki/Slow_light

[trostol]

anyone watch Telescope? show about the making of the James Webb Space Telescope

[zeebo]

anyone watch Telescope? show about the making of the James Webb Space Telescope

Just caught that tonite.  Cool show.  It's amazing that with the infrared detection we may see even farther out than Hubble (since things that far away are hugely red-shifted in wavelength). 

[trostol]

Just caught that tonite.  Cool show.  It's amazing that with the infrared detection we may see even farther out than Hubble (since things that far away are hugely red-shifted in wavelength).

yeah..but there is a lot that could go wrong..imagine if it doesnt work right lol 8 billion dollars floating around up there lol

[zeebo]

yeah..but there is a lot that could go wrong..imagine if it doesnt work right lol 8 billion dollars floating around up there lol

Yep due to how far they're sending it out ...  on this one, no quick trips up to earth orbit to whack the thing with a hammer.