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Our Sun a Black Hole?


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Initial post: Jan 21, 2010 7:47:28 PM PST
Cy'Bele says:
Greetings all...I have always wondered what is on the other side of our sun, is it possibly a black hole? and if so where can I find the proof, any references are welcome.

Posted on Jan 21, 2010 7:54:21 PM PST
Gary S. Hurd says:
A "black hole" is a supermassive form of matter. It sucks ordinary matter into itself, and emits massive amounts of energy as that matter is destroyed. We could easily see this energy if it were being emitted near the sun.

Actually, we would be killed by that intense energy if it were that close.

In reply to an earlier post on Jan 21, 2010 7:55:01 PM PST
barbW says:
Every year (for the next few years) during the month of December there will be a 3 million solar mass black hole behind our Sun.

In reply to an earlier post on Jan 21, 2010 7:59:14 PM PST
Last edited by the author on Jan 21, 2010 8:11:57 PM PST
Gary S. Hurd says:
J. black, I think you should explain that more clearly. Momentzzzz seemed a little unclear about how orbits work.

In reply to an earlier post on Jan 21, 2010 8:00:13 PM PST
Last edited by the author on Jan 21, 2010 8:06:26 PM PST
we are in constant motion around the sun, as are all the other planets, astroids, etc. in the universe. If a black hole was on the other side of our sun, we would've found it by now, or if it was big enough been sucked into it. I get scared when I see stuff like this. This isn't Star Trek. Young people are letting themselves get sucked into the foolishness of the media and need to have a reality check.

Posted on Jan 21, 2010 8:04:39 PM PST
Son of Will says:
I really don't think I understand the question. On the other side of our Sun? You mean behind it? Or the back side of the sun? Maybe you should rephrase it. Are you asking if there are any black holes in or around the vicinity of our solar system? *scratches his head*

Posted on Jan 21, 2010 8:11:02 PM PST
Last edited by the author on Jan 21, 2010 8:33:03 PM PST
It must be that song "Black Hole Sun" that's being referred to here? Our Sun is not in a binary star system - as it's lack of orbit around a mutual center of gravity makes clear. The LIGO gravity wave experiment would certainly have detected any interaction of a black hole within many parsecs - and has not. There is no black hole anywhere near the Sun - sorry. Furthermore, the Sun is far below the Chandrasekhar limit (look it up - it's a fascinating concept, first described in a fascinating way by a really fascinating and utterly brilliant physicist). The whole concept is completely wrong - but has a lovely poetic aspect to it.

Posted on Jan 21, 2010 8:20:50 PM PST
barbW says:
Oh, I thought that armed with this one amazing fact Momentzzzz would be sufficiently inspired to learn about about our planet and star and the zodiacal windows and our galaxy's nucleus. Maybe even how the speed of the stars circling the black hole in the center of our galaxy at millions of miles per hour can give us a very good estimate of its colossal mass (even though it's curiously small for the size of our galaxy, when most all 'normal' galaxies have a central black hole 0.5 percent of their host galaxy's mass, so something a little unusual happened to our central BH (more than average collisions - recently), which might explain why it's off center (not in the geometrical center)). Fascinating stuff.

Momentzzzz, go ahead ask your questions, we'll all try to help. Remember, there are no stupid questions..

In reply to an earlier post on Jan 22, 2010 1:49:51 AM PST
[Deleted by Amazon on Aug 26, 2011 2:18:21 PM PDT]

In reply to an earlier post on Jan 22, 2010 10:23:35 AM PST
Joey Danelectro: <<Actually the is another earth, a doppelganger:
Journey to the Far Side of the Sun>>

That would be cool. If it had EXACTLY the same orbit it would have the same period and we would NEVER see it. It is possible? Would it have life? You betcha!

The trouble is, we would have detected it long ago by the gravitational effects on the other planets... sigh...

In reply to an earlier post on Jan 22, 2010 12:57:47 PM PST
[Deleted by Amazon on Aug 26, 2011 2:18:24 PM PDT]

Posted on Jan 22, 2010 4:44:13 PM PST
Cy'Bele says:
Greetings again all....I guess what I intended to express..was that I came across some info that stated that our solar system was binary and that the twin star was a red dwarf star....? Mr. A Ramone with all due respect I am 38 years old, and the question was one of curiosity not foolishness, as I have an inquiring mind, so no need for disrespect."example" Looking at a diagram of a flat disc"our solar system" the sun in the center, and spinning, if you were to look at it from a distance would there be verticle jets streaming out from the sun?What is giving our sun it's motion"spin" is it internally powered or is it an external gravitational force?

Posted on Jan 22, 2010 4:54:54 PM PST
Don Jennings says:
Momentzzz //Looking at a diagram of a flat disc"our solar system" the sun in the center, and spinning, if you were to look at it from a distance would there be verticle jets streaming out from the sun?What is giving our sun it's motion"spin" is it internally powered or is it an external gravitational force?//

I don't think that there would be vertical jets -- but that would not mean that there was a black hole. The sun is almost certainly not part of a binary star system; the motion of the sun would certainly give it away unless it was a truly tiny binary partner. If the partner was big enough to be a black hole (usually taken to be at least 2.4 solar masses -- but probably much bigger) there should be many markers for it.

How does the sun keep rotating? Rotational inertia. Grab a first year physics text. The sun and planets got their spin from slowly spinning gas (that spin induced by the multiple sources of the gas). As the gas condensed to form our star (or any other star) conservation of momentum insured that the system would spin faster and faster (like an ice skater who pulls in her arms during a spin). Once something is spinning, it tends to keep spinning absent something to slow it down; and in space there is no friction and few other forces to slow the spinning down.

Btw - if the sun could collapse into a black hole (not thought possible) then its radius would be about 3 km.

In reply to an earlier post on Jan 22, 2010 5:18:54 PM PST
DonJ: "Btw - if the sun could collapse into a black hole (not thought possible) then its radius would be about 3 km."

Me: Interesting! But perhaps I need some clarification . . :
1) I thought that singularities were single points compressed into a tiny amount of space, rather than smeared out over a number of km. Was I wrong?
or maybe 2) I thought black holes were a kind of singularity . . . am I wrong about *that*?

In reply to an earlier post on Jan 22, 2010 5:23:10 PM PST
Cy'Bele says:
Thank you Don J....very interesting points....there is a lot of misinformation floating about...and this was the foundation of my question...I appreciate your response, as this is a very interesting subject, as well as thought provoking!

Posted on Jan 22, 2010 7:19:24 PM PST
Cy'Bele says:
Just curious as to why the certainty our sun will not collapse into a black hole?

In reply to an earlier post on Jan 22, 2010 7:25:00 PM PST
Gary S. Hurd says:
Momentzzzz wrote, "Just curious as to why the certainty our sun will not collapse into a black hole?"

It has too little mass.

In reply to an earlier post on Jan 22, 2010 7:36:47 PM PST
Don Jennings says:
D Ritter says //1) I thought that singularities were single points compressed into a tiny amount of space, rather than smeared out over a number of km. Was I wrong?
or maybe 2) I thought black holes were a kind of singularity . . . am I wrong about *that*?//

I used words sloppily: I should have said the radius of the event horizon -- that is the point of no return of anything - including light.

As to a black hole being a "singularity" -- that is what General Relativity predicts; but this poses problems and since it is known that General Relativity breaks down at quantum dimensions, it is not clear that the singularity is real. It would be a point of infinite density (NOT mass - but mass per unit volume). Really, until a coherent theory of quantum gravity is devised, we don't know what is in the interior of a black hole.

Oh - and as to the Big Bang -- per a cosmologist named Max Tegmark whom I saw lecture on a SciAm cruise, we don't know anything about the Universe before the expansion plus about 10^(-30) second. Some physicists now say (I got this from a physicist poster in this group) that our big bang (maybe better called a "rapid inflation") is something that happens locally all over an infinite universe -- each expansion creating a new sub-universe from which the mother universe is inaccessible. (I just read about this so I have probably misstated it)

In reply to an earlier post on Jan 22, 2010 7:43:14 PM PST
Don Jennings says:
Momentzzzz says:
//Just curious as to why the certainty our sun will not collapse into a black hole? //

Gary is correct -- the sequence of events that are thought to create a black hole include there being enough mass to overcome the resistance of electrons being united with protons - when there is enough matter for this to happen you get a neutron star: a body where all the protons and electrons have been mashed together by the star's mass to make all the mass into neutrons. One path to a black hole is for a neutron star to be a binary with a conventional star and suck off matter from that star. If the mass passes some limit then the gravitational attraction will overcome a force called "quantum pressure" -- the resistance of any particle to be in a specific location per the Heisenberg uncertainty principle. When this limit is reached, GR says that there will be a catastrophic collapse to a singularity.

In reply to an earlier post on Jan 22, 2010 9:09:18 PM PST
Pulling out my copy of General Theory of Relativity by P.A.M. Dirac:

"All we can say definitely is that the Einstein equations allow it. ... It would take an infinite time to do so by our clocks, but only a finite relatively to the collapsing matter itself."

I haven't checked Dirac's math on this.

Hawking predicts that black holes evaporate via quantum mechanics: (The short, and potentially confusing version. Wikipedia is much more complete: http://en.wikipedia.org/wiki/Hawking_radiation )

Essentially there are virtual particles because the Uncertainty Principle does not allow for zero energy. (Also called zero-point energy, popular in certain SF tv shows. ) This allows particles to come into existence in pairs based on this energy, (if they weren't pairs charge and momentum would not be conserved). Normally these particles annihilate each other and turn back to energy. Hawking proposes that under certain conditions, next to the event horizon of a black hole, one particle will fall in and the other will escape. That means the black hole actually give up energy. When the black hole begins emitting more hawking radiation at a higher rate than consumes the black hole will eventually evaporate.

(Hope I didn't leave something dumb out of the explanation.)

So when you combing Hawking Radiation eventually causing a black hole to evaporate, and the time dilation inside the black hole the singularity will never physically happen because the black hole will evaporate first.

In reply to an earlier post on Jan 23, 2010 9:10:09 AM PST
Last edited by the author on Jan 23, 2010 9:31:29 AM PST
Gary Hurd: <<Momentzzzz wrote, "Just curious as to why the certainty our sun will not collapse into a black hole?"<
It has too little mass. >>

I had addressed this earlier when I posted: <<Furthermore, the Sun is far below the Chandrasekhar limit (look it up - it's a fascinating concept, first described in a fascinating way by a really fascinating and utterly brilliant physicist).>>

I should have posted more.

From wikipedia: "The Chandrasekhar limit limits the mass of bodies made from electron-degenerate matter, a dense form of matter which consists of nuclei immersed in a gas of electrons. The limit is the maximum nonrotating mass which can be supported against gravitational collapse by electron degeneracy pressure. It is named after the Indian astrophysicist Subrahmanyan Chandrasekhar, and is commonly given as being about 1.4[1][2] solar masses. As white dwarfs are composed of electron-degenerate matter, no nonrotating white dwarf can be heavier than the Chandrasekhar limit."
http://en.wikipedia.org/wiki/Chandrasekhar_limit

Because the Sun is below the limit (1.4 solar masses) the Sun will become a white dwarf. The well understood electron degenerate force guarantees that when the Sun runs out of fuel and collapses in on itself it will not have enough mass to counteract the force that electrons will exert outwards to resist being shoved further together. If the Sun was heavier than 1.4 solar masses (actually it would have to far heavier than that because stars outgas a great deal during their final life stages before collapse - it would have to END UP with more than 1.4 solar masses) the electrons would be compressed so hard that groups of them would compress together to form neutrons (forming a neutron star). That's the end of the line for matter. Beyond that there's only the complete collapse of matter to form a black hole if the mass of the remnant is beyond the Tolman-Oppenheimer-Volkoff limit.

In reply to an earlier post on Jan 23, 2010 11:00:08 AM PST
Don Jennings says:
No Name //"All we can say definitely is that the Einstein equations allow it. ... It would take an infinite time to do so by our clocks, but only a finite relatively to the collapsing matter itself."//

The math is available in GR text books and not original to Dirac (his strong suit was quantum mechanics). The collapse is difficult to conceptualize but the apparent paradox between what an observer outside sees and an observer near the event horizon sees was clarified to me in this example (if this is something you already know, my apologies -- but others read this thread so maybe they will find it useful):

First - gravitational time dilation: clocks or anything clock-like (a photon with a given frequency, for example) will tick slower (or the photon will red shift) in a stronger gravitational field as observed by someone in a weaker gravitational field; e.g., a clock nearer a black hole versus an observer further from a black hole.

Imagine a clock falling toward the event horizon while sending out a tick every "second" as seen by the clock (to the clock nothing seems weird about time). To the observer the clock's ticks get slower and slower -- i.e., further and further apart. The time between ticks approaches infinity so the observer never sees/hears the last tick the clock made before crossing the event horizon -- the observer's pov is that the clock just gets closer and closer to the event horizon.

The clock, however, knows it made a final tick before crossing and it is just falling into the abyss.

The time dilation will happen because gravitational red shift is a property of all gravitating bodies, not just black holes. Black holes just have the property of shifting all frequencies to zero ultimately.

Yes, in about 10^30 years after the last matter falls into a medium sized black hole, it will evaporate. The big problem with that is what happened to the information that fell in. Leonard Susskind thinks that the information is preserved on the surface via that last tick that never comes.

In reply to an earlier post on Jan 24, 2010 8:50:12 AM PST
barbW says:
This loss of information (usually it's the question of the angular momentum of the infalling mass) gives us a hint that we're on the right track when we ponder a universe coming out of nothing. Can we assume by this that no information survives the cusp between universes? This has huge implications for our ultimate origins.

So, not only will all matter be swept up by black holes and transformed into virtual particles within 10,000 googol years, but all the information about that matter will be forever lost.

So the question is, what do you think will happen when field strengths in the first regions which reach so near to max entropy, relax to zero? When virtual particle pairs first no longer recurve together to re-annihilate, what do you think will happen? What will stop gazillions of new baby universes from emerging in THAT far distant future? Is this what happened in our parent universe less than 14 billion years ago?

In reply to an earlier post on Jan 24, 2010 9:21:23 AM PST
barbW says:
Hi Joshua,
I wanted to quickly note that electrons and protons combine to form neutrons and neutrinos in this scenario. I know you didn't mean to give the misleading impression that "the electrons would be compressed so hard that groups of them would compress together to form neutrons", but it caught my eye.

In reply to an earlier post on Jan 24, 2010 9:29:39 AM PST
J. Black: <<I wanted to quickly note that electrons and protons combine to form neutrons and neutrinos in this scenario. I know you didn't mean to give the misleading impression that "the electrons would be compressed so hard that groups of them would compress together to form neutrons", but it caught my eye.>>

Thanks - I got that totally wrong. I'm no physicist - it's abundantly clear. I was posting off the top of my head without proofing and made a rookie blunder.
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Discussion in:  Science forum
Participants:  12
Total posts:  34
Initial post:  Jan 21, 2010
Latest post:  Jan 28, 2010

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