Black Holes

chew_on_this · Jul 15, 2005

No, not "Nuff said". When I said that someone may use the term acceleration disk when actually referring to accretion disk, I meant that they might use it, but it would be wrong. I suppose seeings this is a womans college, you'll claim it's the dumb bishes fault. http://physics.rmwc.edu/ssattar/black_holes.htm That's the last post I'll make on the subject. If you have a problem with it's usage, take it up with Randolph-Macon.

labguy · Jul 15, 2005

My last post too. -The site wouldn't open. -YOU were the first to "correct" some poster when they said accretion disk. -Quite a few have since said that accretion is correct, not acceleration. -Even the HST site with the photo. -I will promise to start using the term acceleration disk every time I post to an Astrology site.

tellmestuff · Feb 22, 2006

what exactly is a black hole besides a collapsed star or whetever. I know we dont know a lot about them but i haer all this stuff and wanted it in english. How can time be affected? someone explain this...

Saiph · Feb 23, 2006

a black hole is a source of intense gravity. Under general relativity gravity isn't a force like magnetism. It's a distortion in a "fabric" called space-time. Spacetime is a common reference frame people will all agree on, regardless of relative velocities, accelerations, or gravity. While someone traveling at .9c will disagree with us (who are stationary) about which of us is moving, and how fast clocks are ticking...we will both agree on the total space and time between events, though one of us may say its more space, than time, or vice versa. A black hole is a distortion so intense, it perpetuates itself. It also causes the distortion in space-time strong enough that a section loops back on itself. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

tellmestuff · Feb 23, 2006

hmmm....im more confused

why06 · Feb 23, 2006

I'll get back to you on this... but first let me explain gravity to you. Gravities ulitmate triumph is a black hole! When the idea of a black hole was first proposed someone wondered "Hmmm...it seems the more mass an object gets the more gravity it had. I wonder if gravity got so strong that not even light could escape and the mass of the star forced it to collapse. Okay you with me so far? All right now in order to go any further you must know something about gravity...At first gravity was desribed as a pull between objects, but Einstein described it as a dent in space time. I hoped you looked at that picture of the boling ball down below. Okay now the steeper that hole is the faster it's going to go down. A black hole is straight down! A black whole is also very small... lets put it like this. You know those bed of needles they have...have you ever sat on one? well anyway if you did you would know you get pricked unless you spread out your mass, a black hole is all in one spot so it is like you standing tip-toe on those needles...Your gonna get pricked right . Well the same thing applies to a black hole except the smaller IT GETS the more strongly it distorts space time in that one spot then over a large area. You get it? If not please ask another question...I hoped this helped. Read this: http://www.exo.net/~pauld/activities/astronomy/gravitywell.html <div class="Discussion_UserSignature"> <div>________________________________________ </div><div><ul><li>your move...</li></ul></div> </div>

alokmohan · Feb 23, 2006

Imagine you compress a star.At a certain radius its escape velocity is more than speed of light.Then light canot escape it ,we cannot see it.As we cannot see it it is black hole.

danyopizzle · Jul 19, 2006

nothing can escape a black holes grasp, even light. but whats at the pit of a black hole? does it get smashed, my theory for the bottom of a black whole is that it shrinks whatever goes in a black hole into dust. blackholes are such a unique thing in space, its like a tornado but in space

derekmcd · Jul 19, 2006

The center or "pit" of a blackhole is a Singularity. Matter at the Singularity is infinitely dense, gravity is infinitely strong, and space-time is infinitely curved. They are quite unique and interesting to read about. If the earth collapsed and turned into a blackhole (not mathematically possible), all the mass of the earth would be the size of a marble... imagine that! <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

rfoshaug · Jul 19, 2006

<blockquote>In reply to:<hr />If the earth collapsed and turned into a blackhole (not mathematically possible), all the mass of the earth would be the size of a marble... imagine that!<hr /></blockquote> Would that be the event horizon of that black hole? Because the mass shouldn't be as large as a marble if it is infinitely dense (that should mean that the size of Earth would be 0)? <div class="Discussion_UserSignature"> ----------------------------------My minds have many opinions </div>

derekmcd · Jul 19, 2006

You are correct. I used that analogy for illustrative purposes. Technically speaking, there is no solid mass inside a blackhole. When using the term blackhole, that includes both the event horizon and singularity. I suppose I could have worded it better to not be misleading... thanks for pointing it out. All the mass of the earth would collapse into a blackhole the size of the marble. There... that sounds better <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

robnissen · Jul 19, 2006

"Would that be the event horizon of that black hole? Because the mass shouldn't be as large as a marble if it is infinitely dense (that should mean that the size of Earth would be 0)?" You are correct. Current theory is that the event horizon would be the size of a marble, but the mass would continue to shrink to smaller than the size of a quark and never stop shrinking.

ryuu · Sep 21, 2006

<blockquote>In reply to:<hr /> from Valareos I think your answer to this is Black Hole evaporation. around a black hole, virtual particles of matter and antimatter are created and and destroyed continuously. every so often, they are created so close to the event horizon that the antimatter particle is tossed into the black hole, while the matter particle escapes. The result, the mass of the black hole shrinks! now the energy is still conserved, and all teh energy (light, energy from the matter/antimatter anniliations, ect) are in the black hole, but do not account for the mass. When that black holes mass dips below the threshold to where diameter of the event horizon is equal to the diameter of the actual stellar object, it literally explodes as the pent up energy floods from it at the speed of light. Such an explosion would make supernovas seem pale in comparison. Search space. com for Black Hole Evaporation <hr /></blockquote>I’m afraid there might be a problem with the idea of Hawking Radiation for a couple of factors. <blockquote>In reply to:<hr /> from Wikkipedea, Hawking Radiation Overview Black holes are sites of immense gravitational attraction into which surrounding matter is drawn by gravitational forces. Classically, the gravitation is so powerful that nothing, not even radiation, can escape from the black hole. However, by doing a calculation in the framework of quantum field theory in curved spacetimes, Hawking showed quantum effects allow black holes to emit radiation in a thermal spectrum. Physical insight on the process may be gained by imagining that particle antiparticle radiation is emitted from just beyond the event horizon. This radiation does not come directly from the black hole itself, but rather is a result of virtual particles being "boosted" by the black hole's gravitation into becoming real particles. A more precise, but still much s</blockquote>

search · Sep 22, 2006

Maybe this helps Explore http://hubblesite.org/explore_astronomy/black_holes/ in above website http://hubblesite.org/explore_astronomy/black_holes/modules.html http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970425b.html Here some websites with animations to shear up the croud http://antwrp.gsfc.nasa.gov/htmltest/rjn_bht.html http://chandra.harvard.edu/resources/animations/blackholes.html http://www.spaceref.com/tools/vi.html?id=139&cat=blackholes&imgs=movie http://www.spaceref.com/tools/imgcathp.html?cid=1 http://www.space.com/php/video/player.php?video_id=BlackHoleBirthBurst

alokmohan · Sep 22, 2006

What about acceleration disc?I never heard it anywhere.

Saiph · Sep 28, 2006

Steve's right, mostly (he's overstating the case for it a bit though). You're understanding of why the BH loses mass is indeed flawed. It has nothing to do with the mass of the particle absorbed, or the mass of the particle emitted...not directly anyway. If it did, you're right in that the mass lost equals the mass gained. However that isn't the entire picture. The other thing the BH does is seperate the particles, and overcome their binding energy. By swallowing one, and "allowing" the other to escape the BH inputs enough energy into the particle pair to overcome their binding energy, energy that is normally regained/returned when the two particle annihilate. That binding energy is related to the mass of the particles, charge, etc. Now, if both fall in...then the BH hasn't overcome their binding energy, they annihilate, the net energy is returned to zero (as it always was actually)...and the BH doesn't change. As for the existence of virtual particles, it isn't a fact, and I've actually chatted with some quantum researchers about it. The experimental evidence in favor of their existence is the Casimir effect, but the results haven't been shown to be due only to the existence of virtual particles. I.e. it hasn't completely isolated them as the only cause. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

gammarayburst · Sep 29, 2006

Not to burst your bubble friends, but how can it be that it is gravity in the black hole that captures everything when gravity is still only a theory and is not understood. I propose that Einstein was a bit misdirected.. sorry "big E" but listen to this. Particles of energy are manipulated by magnetic fields as shown with an electrical current. So why can't the stars magnetic field be the cause of the energy not being able to escape? Same with gravitational lensing, its the magnetic field that causes the particles of energy to bend not gravity. The evidence for this will show up when our dark star Sagittarius A points it's magnetic pole at us for one year starting on December 21 2012. If this idea is true then we will see a massive amount of energy coming from the "dark star". If we see this energy then gravity is not what is holding the energy back it would be the magnetic field. Right now we see giant x-ray flares coming from Sag. A. and the closer we get to that date in 2012, the bigger these energy flares will become. Gamma ray bursts are seen for only a few seconds. If they are coming from black holes then the energy can only escape at the stars magnetic poles. These two places are the only places where the magnetic field lines are 90° to the surface. Being 90° to the surface allows the energy to follow an escape route. If the star rotates the gamma rays "or energy" emitted appear to be a burst when viewed from one point, but actually the energy is continuiously being spewed out. Time will tell.

Saiph · Sep 29, 2006

First, gravity is understood as well as magnetism is, so I could turn your arguement against gravity right back at you. Why, afterall, does having a charge move create a field of force hmmm? Now as for the specifics of your arguement: Only moving, charged particles are affected by magnetism. Photons, while moving, are not charged. As such the magnetic field does nothing to redirect their course, and cannot produce the expected effects of traditional black holes. However, the magnetic fields do have very significant effects on the BH's surroundings, as they help and cause the formation of the ever popular "polar jets" of relativistic charged particles observed from BH's and other objects. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

alokmohan · Oct 12, 2006

Saggitarus is a dark star?How you say so?

sterling1970 · Jan 31, 2008

If black holes are so strong that light and time cannot escape, couldn't you say that time stops during that same time frame? And if these are "doors" leaving our Universe, where are the ones coming into our Universe. You should be able to see those as well.... shouldn't you? Do you think that is what the streams of light emitting from some black hole centers?

weeman · Jan 31, 2008

First of all, we have no proof that suggests that black holes are doors that lead to another universe or dimension. White holes are one theory as to what the other end of a black hole looks like. It has been theorized that black holes are entrances to wormholes, but like I said, no evidence has come forth. When you say streams of light, I'm assuming you mean the jets that rocket away from a black hole? These are composed of highly-energized matter that is being ejected back into space from the accretion disk at close to the speed of light. One theory suggests that the jets found coming from black holes and quasars consist mostly of protons and electrons. No light can come from the black hole center, because the center is the singularity. Once beyond the event horizon, nothing can escape, not even light. If you were to travel beyond the event horizon, it would be impossible to avoid the singularity. It's like trying to avoid five minutes from now, there's nothing you can do to stop it, it is inevitable. <div class="Discussion_UserSignature"> Techies: We do it in the dark. "Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity." -Albert Einstein </div>

jgreimer · Feb 1, 2008

Good answer weeman. However I have a few questions to which I don't know the answers. The Uncertainty Principle mandates that the more a particle's position is restricted, the more average momentum it must have. Unlike velocity, there is no upper limit to momentum because momentum is the product of velocity and mass. As a neutron star begins to collapse and the neutrons get squeezed into smaller and smaller spaces, they become better able to resist additional squeezing with their momentum. So how does the star collapse into a singularity? It seems like a real life example of an irresistible force meeting an immovable object. Why are we sure there is a singularity at the center of a black hole? How does anything ever cross the event horizon? Time stops completely and space contracts to nothing at the horizon. In our time an in falling object would fall forever but never quite reach the horizon. Nevertheless the horizon would continue to grow as more matter falls in but each particle would see its own unique horizon that it wouldn't be able to reach before the black hole evaporates.

alokmohan · Feb 1, 2008

First understand singularity and then you know.

shadow735 · Feb 1, 2008

My job is a black hole, there is no escape and it seems like you are stuck in the same place forever.. <div class="Discussion_UserSignature"> </div>

origin · Feb 1, 2008

The main thing (if you will) that trys to stop the collapse of star past the nuetron star state to a singularity or black hole is the Pauli exclusion principle. For this case it basically says that 2 nuetron cannot occupy the same space. But general relativity indicates that gravity can be so strong that it overcomes the Pauli exclusion. There is a pretty good write up on wikipedia on this. They say that the gravity is so intense that the nuetrons essentially breakdown into quarks so the Pauli exclusion principal does not apply, it is only for ferrimons. <div class="Discussion_UserSignature"> </div>

Black Holes

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