Astrophysics question

[Jaxom]

Re: Astrophysics question

 

Vinnie the Pooh....

 

I may have to build a super-powered mafioso with ursine powers just to use that name. And give him a henchman who is an astrophysicist to supply them with really evil homework sets (or weapons if the find a need).

[Zeropoint]

Re: Astrophysics question

 

Broken how? (In layman's terms if possible please) Are there any dominant theories?

 

Somebody dropped it.

[Comic]

Re: Astrophysics question

 

The idea of broken symmetry hinges on there being more than one way to annihilate a fundamental particle.

 

If matter and antimatter mutually annihilate, there's symmetry.

 

If either one or the other are randomly sucked in by some other effect there's probabilistic symmetry.

 

If one is dominantly sucked in by some other effect, there's asymmetry.

 

Matter and antimatter have opposite 'handedness', which is a property that isn't so easy to explain or observe in the modern universe, and its interactions are poorly understood. But likely left-handed particles tended to fall into gravity wells, causing right-handed particles to 'tunnel' out, creating new mass in the Universe.

 

(Well, not new mass, since the mass of the gravity well would decrease by that amount. Somehow.)

[Midas]

Re: Astrophysics question

 

That's sort of the idea. There isn't a paradox. It's the result of the photons that reach you from the fall-in event having themselves to crawl out from the edge of the hole. This isn't the right picture, but it's convenient to think that the closer the photons from the falling-in are to the event horizon when they start out, the longer it takes them to spiral their way out of the deep gravity well of the black hole. It just takes a while to get the signals from the very edge of the black hole; for the thing that's falling in, the experience is over very, very quickly.

 

OK, I've had a question about this for years, and another that just occured to me (and maybe the answer). Isn't there a tremendous red shift in this event?

 

And second, where do the photons "come from." While the McGuffin fell into the gravity pit, from an outside observer's POV, the McGuffin is still hovering on the event horizon. How does the light energy continue to broadcast?

 

Hope I'm making sense with the question, Cancer's post doesn't *quite* answer it.

 

Midas

Who is still trying to figure out how an energy packet -light- can travel at the speed of light)

[Nyrath]

Re: Astrophysics question

 

Who is still trying to figure out how an energy packet -light- can travel at the speed of light)

Actually, according to Einstein, the answer is because it is impossible a photon of light to travel at any other speed except "c" (the speed of light in a vacuum).

[Cancer]

Re: Astrophysics question

 

OK' date=' I've had a question about this for years, and another that just occured to me (and maybe the answer). Isn't there a tremendous red shift in this event?[/quote']

Yes. In effect, the photon pays a price in energy to crawl out of the gravity well. That energy loss results in a change of the photon's frequency/wavelength to lower frequencies/longer wavelengths, which is a red shift. It doesn't take a black hole to get that, BTW; any/all gravity sources cause such a thing. In principle, that includes even the photon itself. And if you think about that too hard, you'll hurt your brain and start raving about quantum gravity.

 

And second, where do the photons "come from." While the McGuffin fell into the gravity pit, from an outside observer's POV, the McGuffin is still hovering on the event horizon. How does the light energy continue to broadcast?

 

Hope I'm making sense with the question, Cancer's post doesn't *quite* answer it.

 

Yeah, because the analogy I used breaks down there. And to get a better one takes someone who's taken more general relativity than I have, which is to say, any at all.

[Midas]

Re: Astrophysics question

 

Actually' date=' according to Einstein, the answer is because it is [b']impossible[/b]

 

(I added "for" to your reply, is that what you meant to say?)

 

OK, thanks.

 

Could you translate Uncle Albert to layman's terms? As a side note, I presume we are talking about "in a vacuum," since photons do slow down appreciably in other mediums.

 

See, I'm looking at the tau formula, which requires anything with a mass greater than zero (no matter how infantesmally greater) to require an infinite amount of energy to reach light speed. From that, either photons are travelling less than lightspeed, or they have no mass/energy -and can't run photovoltaic cells, much less persuade the optic nerve to send signals to the brain.

 

Midas

[Midas]

Re: Astrophysics question

 

 

Originally Posted by Midas

OK, isn't there a tremendous red shift in this event?

Yes. In effect, the photon pays a price in energy to crawl out of the gravity well. That energy loss results in a change of the photon's frequency/wavelength to lower frequencies/longer wavelengths, which is a red shift. It doesn't take a black hole to get that, BTW; any/all gravity sources cause such a thing. In principle, that includes even the photon itself. And if you think about that too hard, you'll hurt your brain and start raving about quantum gravity.

 

Why not? I have a tendency to rave anyway.

 

In this size gravity well, wouldn't the energy drop take the -"vision" for want of a better word- quickly into infrared and sub infrared?

 

What I'm thinking of is the vision of "glittery" black holes. Without stuff eventually seeming to cross the event horizon, you wouldn't have a "black" hole, you'd have a disco ball; showing every object that fell in appearing on the surface of the event horizon.

 

Yeah, because the analogy I used breaks down there. And to get a better one takes someone who's taken more general relativity than I have, which is to say, any at all.

 

'sOK. It's been bugging me for years, I can wait a few more.

 

Special Relativity I had no problem with:

1) Only applies to near lightspeed math

&

2) No matter what you do the answer is "=c" or "=c {squared}".

 

Never quite got general relativity though, couldn't quite wrap my mind around the concept.

 

Midas

[Nyrath]

Re: Astrophysics question

 

See' date=' I'm looking at the tau formula, which requires anything with a mass greater than zero (no matter how infantesmally greater) to require an infinite amount of energy to reach light speed. From that, either photons are travelling less than lightspeed, or they have no mass/energy -and can't run photovoltaic cells, much less persuade the optic nerve to send signals to the brain[/quote']

Ah, the key here is that photons have no REST mass (aka invariant mass). They do have relativistic mass, so they can run photovoltaic cells and persuade the optic nerve to send signals to the brain.

[Cancer]

Re: Astrophysics question

 

In this size gravity well' date=' wouldn't the energy drop take the -"vision" for want of a better word- quickly into infrared and sub infrared?[/quote']

Yes. In fact, an alternate way of expressing this is that photons that start out inside the event horizon get redshifted out of existence: they have insufficient energy to pay to get out of the black hole.

 

Severe redshifts are known in astronomical and cosmological sources. The cosmic microwave background radiation has a spectrum that peaks at about 2 mm now. That peak started off in the near infrared.

 

What I'm thinking of is the vision of "glittery" black holes. Without stuff eventually seeming to cross the event horizon' date=' you wouldn't have a "black" hole, you'd have a disco ball; showing every object that fell in appearing on the surface of the event horizon.[/quote']

In principle, yes, but the intensity of the radiation drops very rapidly as time goes on. (The number of photons coming per second of time as measured by the observer is falling, as each second of observer's time represents a smaller and smaller time interval in the faller's frame; and the redshift is reducing the energy each photon carries.) So the glitter from each infall actually fades out very, very quickly.

[StGrimblefig]

Re: Astrophysics question

 

Because it is somewhat relevant to the ongoing discussion here, I wonder if anyone has seen and/or has comments on this article: http://arstechnica.com/news.ars/post/20070622-apotential-solution-to-the-black-hole-information-loss-paradox.html

 

The bottom line of the theory is that matter falling into a black hole never actually crosses the event horizon. In this way, the information carried in that matter is not "lost," just changed in form at the event horizon.

 

The problem I have with the problem (the so-called "information loss paradox") and this solution is that they assume that the matter/information is not changed in form within the event horizon, yet it can be changed AT the event horizon. Given the theory that within the event horizon the laws of physics are not applicable/drastically different, this whole argument seems silly.

 

Or have I missed a decade or more of astrophysics progress/debate?

How many slashes does it take in a posting to create a singularity?

[Midas]

Re: Astrophysics question

 

Ah' date=' the key here is that photons have no [b']REST [/b]mass (aka invariant mass). They do have relativistic mass, so they can run photovoltaic cells and persuade the optic nerve to send signals to the brain.

 

Much Grass.

 

I'll check the links when I can find more time. (I'm chauffering some relatives who are layed over in Dallas, so whenever the rains let up...)

 

Midas

EDIT: Nyrath and Cancer repped.

[Dr. Anomaly]

Re: Astrophysics question

 

The original question gets down to the roots of (potential) CPT violation; I'll see if I can think of a way to abstract some of that down to very general terms a bit later, when I have some time and am not dog tired...

[Vestnik]

Re: Astrophysics question

 

The original question gets down to the roots of (potential) CPT violation; I'll see if I can think of a way to abstract some of that down to very general terms a bit later' date=' when I have some time and am not dog tired...[/quote']

 

Please do!

[Adam Kadmon]

Re: Astrophysics question

 

Could you translate Uncle Albert to layman's terms? As a side note, I presume we are talking about "in a vacuum," since photons do slow down appreciably in other mediums.

 

Actually photons only appear to travel slower than light speed in other mediums. They are in fact travelling at the speed of light but are bouncing back and forth between the heavier particles.

 

As an example, it takes about 30,000 years for a photon to go from the Sun's core to its surface, but takes only 8 minutes for the photon to travel from the Sun's surface to the Earth.

[Jaxom]

Re: Astrophysics question

 

Actually photons only appear to travel slower than light speed in other mediums. They are in fact travelling at the speed of light but are bouncing back and forth between the heavier particles.

 

Simple thought experiment invalidates this. Light travels at different speeds in different media without scattering or coherent light beams would not be possible in anything but a pure vacuum. A laser could not exist nor could a rainbow which is an example of coherent light separating specifically because of differences in speed in the medium.

 

Your statement about photons leaving the sun is essentially correct but this is a different realm of physics (scattering). It's also why the sun radiates what is essentially a black-body spectrum around 5000K.

[pinecone]

Re: Astrophysics question

 

Simple thought experiment invalidates this. Light travels at different speeds in different media without scattering or coherent light beams would not be possible in anything but a pure vacuum. A laser could not exist nor could a rainbow which is an example of coherent light separating specifically because of differences in speed in the medium.

 

Your statement about photons leaving the sun is essentially correct but this is a different realm of physics (scattering). It's also why the sun radiates what is essentially a black-body spectrum around 5000K.

 

Yeah, thats where chanrasaker radiation (sp?) comes in...its emitted when something exceeds the local speed of light.....

[Cancer]

Re: Astrophysics question

 

You're thinking of Cerenkov radiation, emitted when a charged particle (not a photon) passes through a medium at a speed faster than the speed of light in that material but not faster than the speed of light in vacuum.

[theltemes]

Re: Astrophysics question

 

Traveling through a medium, the group velocity changes while the phase velocity remains at the speed of light in a vacuum.