Black Holes

frobozz · Aug 19, 2005

I don't think it would nessarily be a grave danger to the Earth (so long as it didn't say physically hit the Earth so to speak). It should just perturb the orbits of the planets slightly. Provided that the orbits of the planets are stable from a dynamics point of view (which I believe they are, however please correct me if this assumption is wrong) then the errors in the orbit should stamp themselves down to zero and things should return to normal again over a period of time. On what may be an unrelated subject, but still tied to this, is that if such a black hole perturbed the earth even for a short period of time, would the effect on the weather be sufficient to warrent being worried about it?

contracommando · Aug 21, 2005

“On what may be an unrelated subject, but still tied to this, is that if such a black hole perturbed the earth even for a short period of time, would the effect on the weather be sufficient to warrent being worried about it?’ Yes. If a relatively large black hole (example being one of 10 solar masses or higher) passed near our solar system (or through it), then the consequences would be disastrous. Planets could be thrown out of the solar system or into the sun. If ejected, our planet would freeze fairly quickly. If hurtled into the sun, our oceans and atmosphere would boil off. However, if a black hole passed at a significant distance, and the effects on the Earth’s orbit were only modest, then only a small change in weather might result (depending on the mass of the black hole, locations of the planets, distance at which it passed, etc). Any change, however, in the Earth’s orbit might result in disaster-even if the changes were only minor. Some scientists have speculated that small changes (wobbles?) in either the Earth’s orbit around the sun or the sun’s orbit around the Milky Way may have caused the ice ages. If the orbit of the Earth were changed by a black hole, then the damage might be significant.

nexium · Aug 21, 2005

All that appears to be correct, except how can changes in the Sun's orbit about the milky way cause an ice age or global warming? Neil

nexium · Aug 21, 2005

Do I wrongly understand that Earth is about 26,000 light years from the center of the milkyway galaxy instead of 40,000 light years? Neil

one_billy · Aug 22, 2005

So what happens to the galaxy when it's black hole evaporates? <div class="Discussion_UserSignature"> </div>

Saiph · Aug 22, 2005

Well, by the time a supermassive blackhole (the type in the core of almost all galaxies) evaporates....the galaxy as a whole will be long dead (no active stars, just black holes, cooled white dwarfs, etc). When it does...not much I suppose. <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>

frobozz · Aug 24, 2005

I believe I saw that movie as well. However, assuming the current theory on the evaporation of black holes, it should be possible to make mini-black holes which dissipate before they cause any real damage.

nexium · Aug 27, 2005

True: Mini black holes are thought to evaporate in minutes. If we can feed matter though the event horizon faster (ain't easy) than the evaporation rate: The black hole will be less mini, evaporate in hours or become sufficiently massive to cause large scale danger. Neil

kmarinas86 · Aug 27, 2005

or become sufficiently massive to cause large scale danger. If you jam a mini black hole into a bar of uranium. Guess what happens.... You will be absorbed into the uranium bar as fast as it was absorbing you earlier. The uranium bar, however, will shrink <insert innuendo here />, and it's surface gravity is infinite. The uranium bar's gravity at any distance outside its original radius will be just the same. It's only because its surface is compact is why you get the high level of gravity at distances that are smaller than the bar's original radii.

rodrunner79 · Sep 12, 2005

<blockquote>In reply to:<hr /> I, if I’m not mistaken, believe that the CERN supercollider, when it comes on line, might try to create mini-black holes in the laboratory to study instead. <hr /></blockquote> There's a man-made black hole, alright. It's called Congress.

alexanderc · Sep 18, 2005

me accede he of Attitude

pyoko · Oct 14, 2005

A lot of people are skeptical about black holes. Or at least to the mathematical simulations that people come to think of pretty but pointless. What do you think black holes, or the phenomena observes as 'black holes' with radiation streams etc really are? <div class="Discussion_UserSignature"> -pyoko the duck It is by will alone I set my mind in motion. </div>

CalliArcale · Oct 14, 2005

Objects sufficiently dense that there is an orbital altitude above them which has an escape velocity of "c" or greater. (c = the speed of light) <div class="Discussion_UserSignature"> "People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff." -- The Tenth Doctor, "Blink" </div>

pyoko · Oct 14, 2005

Is there a singularity or are they just dense? Neutron stars are pure neutrons. Something even more dense is composed of what? Pure quarks but with a finite dencity that is close to infinite but not quite there to form a perfect singularity? <div class="Discussion_UserSignature"> -pyoko the duck It is by will alone I set my mind in motion. </div>

Saiph · Oct 15, 2005

Good question that...Various aspects of GR point towards a "singularity" like center, though that core can vary a bit. We won't be sure until we figure out a way to mesh quantum mechanics with general relativity. <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>

Saiph · Oct 17, 2005

Not a clue, they're generally outside my realm of expertise. I actually know very little about the inner workings of GR, and of quantum mechanics (ugh, I'm working on some homework for the subject as we speak, double ugh). Basically the issue is how do you reconcile GR, which requires a continous description of spacetime and curvature to be gravity, and quantum mechanics, which uses descrete particles and force carriers. <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>

rodrunner79 · Oct 17, 2005

When you fill a sink with water then you pull the plug, the water drains counter-clockwise into a spiral shape (rotates), much like hurricane and much like spiral galaxies and much like blackholes. Many scientist theorize blackholes (drain plug) exist in centers of galaxies, and matter tends to rotate around these objects. Could it be possible that dark matter holds stuff together and it is some sort of liquid?

pioneer0333 · Jan 6, 2006

What will happen if two black holes collide? Will they merge together, destroy each other, or just repell each other? <div class="Discussion_UserSignature"> </div>

kmarinas86 · Jan 6, 2006

They merge.

rodrunner79 · Jan 6, 2006

Wasn't there a thread like this a couple of months ago??? Same exact questions too.

Saiph · Jan 6, 2006

there's always a thread asking this question within the last few months. Why? cause it's a good question and the search function at SDC isn't very good. Its one reason I had a Black Hole reference post before the crash. <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>

abhinavkumar_iitr05 · Jan 29, 2006

I am not familiar with any such similar post but as far as my knowledge they will merge & create an even more massive BH.There is no reason for their repulsion as Gravitational force is never repulsive.As I know a similar event was observed by the nasa scientists.Ofcourse there will be a release of tremendous energy but that too will take place for a very very short time as the curved space & time will become more curve and thus the escape of energy will stop.

nexium · Mar 31, 2006

A glancing merger is much more likely, where the event horizons over lap slightly and briefly. If approximately equal mass and the speed difference is large, perhaps ten black holes could be the result. Few if any, would leave at sufficient speed to avoid future collisions which would be at lower speed resulting in re-capture within seconds. Several black holes orbiting each other for millions of years is not improbable. Results are likely much different for a pair of billion solar mass black holes as compared to a pair of billion ton black holes, if any exist with that small mass. Very little mass escaped/recapture is delayed long term. Please comment, refute and or embellish. Neil

derekmcd · Apr 1, 2006

My understanding is that in the early universe (1 billion or so years), galaxies would often collide and thus the black holes would merge. Quasars are are believed to be evidence of this. <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

Black Holes

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