Black hole effects on our galaxy in 10E18 years

[nexium]

If our galaxy averages one new black holes each 100 years, we now have 137 million black holes, They may have typically lost 0.1% of their mass by Hawking radiation, but most of them would have accreted more than 0.1% resulting in a net mass gain for most of the compact stars.<br /> After a million times a million times a million years = 10E18 (close enough to the end of time for most purposes), nearly all of our galaxy's mass will be in the 100 biillion 10E11 blackholes and other compact stars, so they will be accreting very little, resulting in some of them shrinking to nothing.<br /> 99.999999% of the stars will be compact and cold, by then, so the planets will be very cold, but some will be intact.<br /> Our galaxy will likely have about 1/2 the present mass, will rotate slower and likely will have increased in volume by several times. Collisions are quite rare now and will be even more rare in the far future. Please embellish, comment, correct or refute. Neil

 

[qzzq]

The Big Rip could destroy everything in 3 billion years from now. But when you're right, a lot of very advanced civilizations will be doing battle over the remaining habitable planets. <img src="/images/icons/crazy.gif" /> <div class="Discussion_UserSignature"> <p> </p><p>***</p> </div>

 

[paleo]

"If we average new black holes each 100 years'<br /><br /> What is the basis for that figure and how would it be a constant? Is it an educated estimate? Wouldn't the rate of black hole formation increase as the average age of stars in our galaxy increases? And start to drop off dramatically as there would be be less stars formed as the galaxy ages...and thus less stars with sufficient mass to become black holes.

 

[nexium]

Hi paleo: I think I disagree, black hole formation is decreasing slightly. I guessed one per hundred years is average for our galaxy to date. 100 trillion black holes would form if constant, but there is likely not enough matter in our galaxy for more than a trillion, so it has begin to taper off as new stars are not being born as often as in the past. Neil

 

[a_lost_packet_]

What about the limitations of a black-hole's effect on the surrounding matter? SMBH's such as the one at the center of the Milky Way have a limited "reach." Are you saying that regardless of orbit, all matter will be consumed? Eventually, even a SMBH will consume everything within a limited distance. However, in order to "get" all the matter into all the SMBHs wouldn't systems have to be significantly disturbed past the point of the "terrifying equilibrium" distance with a SMBH? If so, how would that happen considering expansion? Would the time it would take to achieve these disturbances be longer than the energy in the Universe would allow? ie: Before total consumption would take place the Universe would fizzle out into the long, dark "freeze."?<br /><br /> <div class="Discussion_UserSignature"> <font size="1">I put on my robe and wizard hat...</font> </div>

 

[thalion]

There's been a lot of theoretical work on this; I'll go along as I understand cosmologists see the future unfolding; see Adams's and Frank Laughlin's excellent "The Five Ages of the Universe", and the old Time-Life book, "The Frontiers of Time."<br /><br />As paleo mentioned, the black hole rate will undoubtedly decrease as time goes on. After the starbursts caused by the merging of the Magellanic Clouds, then M31 with the Milky Way, probably almost all of the gas will be used up. My round guess is that by say 20 billion years from now, star formation will be virtually nil.<br /><br />The time frame of 10^18 years is not long enough for any stellar black hole to evaporate; a solar-mass black hole would take 10^67 years to evaporate. I also think there are considerably less than 137 million black holes in the Milky Way; most of the current population probably formed at the peak of star formation some 8-5 billion years ago, with a steadily-declining rate since then, and the stars massive enough to form black holes (maybe some 15 solar masses and up) have probably always been very rare, even during the peak ages.<br /><br />You are right, collisions will still be rare. However, more important than collisions will be gravitational scattering. When two stars pass very close to each other--and these events will be much more common than collisions, even if they are also rare--they will undergo a kind of slingshot effect that will change their speeds, with the more massive star losing momentum and the smaller one gaining some. If this happens only once in a million years somewhere in the galaxy, there will have been a trillion events by 10^18 years in the future. The net effect will be to eject the lowest mass stars from the galaxy, while making more massive objects (stars, degenerate objects and black holes) migrate towards the center, ultimately to feed the supermassive black hole at the center.

 

[nexium]

Hi Thalion and lost packet; That is a lot of great information. I did not mean to imply that the blackholes would get more than 1/2 the matter even in 10E67 years. I gussed one trillion was the upper limit of black holes for our galaxy. Perhaps even 100 billion is more than likely, since evaporation is slower than I guessed and 0.1 percent average accreation is likely low even for the past 5 billion years.<br /> Do we have measurements indicating the Magellanic clouds will merge? Will they stay merged or just pass though each other? <br /> True we see perhaps a thousand stars for each O, B and A star we see, and a few of these may be less massive proto stars; but the less massive stars stay 1000 times longer on main sequence, so there could be more black holes than visable stars after 8 billion years, if the tendecy was for more massive stars to be born 8-5 billion years ago in our galaxy. I was thinking my 137 million black holes was likely low as that is less than 1% of the present main sequence stars in our galaxy. How about 8 billion black holes in our present galaxy which would be one per year average for the past 8 billion years?<br /> The high gas and dust density 8 billion years ago made orbits more eliptic which helped form the SMBH = super massive black hole at the center of our galaxy. What mechanism will cause compact stars to merge at the center of our galaxy instead of diverge (= galaxy of increased volume) in 10E18 years = one billion times one billion, when most cubic meters in our galaxy will have less than one particle each? Neil

 

[nexium]

Hi packet: I agree, collissions and disturbances will continue to decrease in our galaxy. While many experts seem to think the expansion of the Universe will not increase the volume of a typical galaxy, the sling shot manuvers will move many of the five solar mass and less objects just outside the present envelope of our galaxy. Conversely some experts are of the opinion that random close passes are just as likely to slow the less massive object. They seem to be of the opinion that the rotational direction of the more massive object relative to the direction of the object that just barely missed determines gain or loss of speed. Can you confirm or refute? Neil

 

[Maddad]

paleo<br />"<font color="Yellow">'If we average new black holes each 100 years' <br />What is the basis for that figure </font>"<br /><br />That sounds like the number of supernovas we get each century. All of them do not collapse into a black hole, but when you're only counting zeros it's close enough.

 

[paleo]

Thanks maddad:<br /><br /> My lack of knowledge makes me just a peripheral observer on a discussion such as this. It is fascinating stuff.<br /><br />As a scientist, however, the bells go off when I read an opening guesstimate which forms the basis of subsequent theory. I just like to know that the guestimate has a basis (as you point out it does).<br /><br /> I won't be a pest and ask the next question as to the number a 'hundred supernovas a century'. It's just that sometimes some non-messuarable phenomena are rounded off with a degree of plus or minus that make them meaningless. Is it a hundred or could it really be 12 or even 312? I'm not asking for a response but rounded numbers should always make us pay a bit closer attention to premises.

 

[nexium]

Hi palio: I like to put numbers on things, so I can perform some simple arithmetic. I corrected the first line which was vaugue and not what I wanted to say. I think Maddad said there had been about 100 super novas in the last 100 years; some make neutron stars, the biggest ones/10%? make black holes according to the theory which changes a little each year. That would be ten new black holes per century = 800 million in the 8 billion years since our galaxy started making stars. perhaps 600 million, if new black holes formed less often the first 4 billion years. The number is not critical to what our galaxy will be like in a billion times a billion years 10E18 as few new black holes will be formed, a trillion years from now as all the present stars will have left main sequence and less than ten main sequence stars is likely by then, if present theories are approximately correct. Neil

 

[paleo]

Thanks for the added info nexium.<br /><br /> I wasn't being ctitical of your numbers in the premise. I have no background in the field to make a judgement.<br /><br /> As for numbers. I agree they help to give persepective. A difference, however, of a factor of 10 (even 2) can make a huge difference when extrapolating consequences over astronomical time scales.

 

[nexium]

Hi qzzq: tell us about the big rip. Neil

 

[a_lost_packet_]

<font color="yellow">nexium - Can you confirm or refute? </font><br /><br />Heh heh. I don't know that I can confirm/refute much there. I'm not a cosmologist. However, I can confirm that it appears the driving force behind the expansion of the Universe is weaker than the force of local gravity holding systems and galaxies together. So expansion would not make localized changes. ie: Galaxy volumes would not expand solely due to the expansion of the space-time fabric over time.<br /><br />I misunderstood the starting post somewhat. I had thought that it was intended to present an idea that most of the mass of the Universe would end up within SMBHs. So, my questions revolved around the mechanism that would create disturbances that would "shuffle" material inside/together which had previously "stable" orbits within their galaxy. In other words, I was just trying to figure out a macro-mechanism to accomplish this. Given that expansion would require that, eventually, distance between galaxies would increase to the point where little to no interaction would take place, I was wondering what other mechanisms could produce such disturbances. (Granted, galactic "collisions" don't necessarily produce the disturbances necessary to affect change in all the mass present. But, it was all I could think of at the time heh heh.)<br /><br /><font color="yellow">nexium - They seem to be of the opinion that the rotational direction of the more massive object relative to the direction of the object that just barely missed determines gain or loss of speed.</font><br /><br />I would assume that momentum could be increased by the effect of a "close pass" by an object would would impart an impulse to the former, stable, object effected. So, a gain of velocity could be affected. Is that what you are describing?<br /><br />Note: I was reading somewhere that stars towards the edges of galaxies and in danger of ejection would, over time, be more susceptable to faster de <div class="Discussion_UserSignature"> <font size="1">I put on my robe and wizard hat...</font> </div>

 

[qzzq]

Neil,<br /><br />The Big Rip is a theory about the end of the Universe. When observations of distant 1-a type supernovae and improved measurements of the cosmic background radiation, the echo of the Big Bang, showed that the Universe is expanding and that this expansion is accelerating, scientist were wondering what would happen if this acceleration of expansion would continue ad infinitum. At a certain moment in the future, the rate of expansion would overcome gravitational forces and in the end nuclear forces, tearing up atoms and the structures of our Universe, Earth included. This would then be the Big Rip. <br /><br />BTW: I think I read somewhere that in our galaxy, black holes form at a rate of 1 every 1,000 years. I'll see if I can find a link. <div class="Discussion_UserSignature"> <p> </p><p>***</p> </div>