Will the black hole of Milkomeda kill us?

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Ann
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Will the black hole of Milkomeda kill us?

Postby Ann » Mon Aug 13, 2012 5:49 pm

Of course I have to rephrase the question in the heading. "We" will hardly be killed by the black hole of Milkomeda, the large elliptical galaxy that will form as the Milky Way and Andromeda merge. Seeing that this event is going to happen about three billion years from now, it's rather optimistic to think that "we" will be around to witness it.

Okay. But this merger will happen, according to the latest measurement by the Hubble Telescope. The Milky Way is a moderately gas-rich galaxy, and Andromeda is less so, but the combined amount of gas in these two galaxies is going to be enough to send enormous helpings of gas into the nuclei of Milky Way and Andromeda. And then, I suppose, the two central black holes will merge.

The problem is not going to be that either of the black hole is going to eat us (quite apart from the fact that we will hardly be around at that time). Rather, the problem is going to be that as this monstrous black hole guzzles tremendous helpings of gas (and I shudder to think what the actual merger of the two supermassive black holes will be like) it is going to burp such awful super-jets that it will clear Milkomeda of much of its gas, and the gas that remains will be hot and turbulent. Also, the black hole will likely blow away the thick dust that is shielding us here on Earth from the antics of the somewhat "moderate" black hole that is lurking at the center of our "unmerged" galaxy.

I'm wondering if the black hole is going to be the kind of monster that tears down all "safety equipment", all the airbags, all the safety belts, all the life vests, all the protection that our galaxy offers us at this time and shields us from the bad behavior of our central black hole.

When the super-monstrous black hole of Milkomeda forms, how likely is it to sterilize a lot of the life that may exist in our two galaxies?

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Re: Will the black hole of Milkomeda kill us?

Postby Chris Peterson » Mon Aug 13, 2012 6:43 pm

Ann wrote:When the super-monstrous black hole of Milkomeda forms, how likely is it to sterilize a lot of the life that may exist in our two galaxies?

I would say yes... although not so much from radiation effects as gravitational ones. However, as the merger will occur over evolutionary time scales, it's also possible that some life will simply adapt. In the end, I expect that there will still be plenty of habitable planets, they'll simply be different from the ones that were around before the collision.
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Re: Will the black hole of Milkomeda kill us?

Postby Ann » Tue Aug 14, 2012 5:59 am

I would like pursue this a little further, Chris.

To me, a large elliptical galaxy seems like an enormously scaled-up version of a globular cluster. Of course there are tremendous differences - a large elliptical galaxy contains many generations of stars, many of its stars are very metal-rich, there is always a gargantuan black hole at the center etcetera - but the turbulent motion of the stars in globular clusters seems similar to the motion of stars in elliptical galaxies.

Searches for planets in Milky Way globulars have turned up - if not nothing, then at least very meagre harvests. This, of course, can't imply that planets are althogether missing in globulars. Rather, tidal forces must have torn planets from their parent stars, leaving them either in orbits that are exceedingly hard to detect or else decoupling them from their stars altogether. So globular clusters should be rather full of free-floating planets. However, globular clusters lose members over time, mostly by ejecting low-mass objects. Since planets are very low-mass compared with stars, quite a few of the free-floating planets ought to have been ejected from the globular clusters.

What is the situation in large elliptical galaxies going to be like? Are well-ordered solar systems like our own going to be common, or are they going to be rare - perhaps exceedingly rare? Are free-floating planets going to be the norm in large elliptical galaxies?

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Re: Will the black hole of Milkomeda kill us?

Postby BDanielMayfield » Tue Jan 01, 2013 3:44 pm

It’s a fascinating question Ann. I have a much more optimistic take on what will happen to our planet when Andromeda and the Milky Way merge. I prefer saying merge over the word collide when speaking of galactic encounters, since with the vast distances between them (excepting dense clusters) stars will almost never collide. Also collisions are rapid, destructive events, whereas when galaxies come together it takes vast lengths of time to unfold and the result is often more creative than otherwise, with new stellar systems forming as dust and gas clouds are compressed.

My reasons for this optimism are at the core religious, so I won’t discuss them here. But there are also sound scientific arguments to be made for an optimistic viewpoint as well. There was a paper reported on in Sky and Tel’s news blog in a Kelly Beatty article back on June 7, 2012 which stated that simulations of this encounter usually lead to star systems in our region of the Milk Way to end up farther from the dangerous core area in the coming giant elliptical galaxy that the local group is destined to become. Here’s the link: http://www.skyandtelescope.com/news/Future-Shock-M31-to-Hit-Milky-Way-Head-On-157990465.html

Warning: If you’re easily offended by biblical references, you might want to avoid reading the blog postings at the end of that article.

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Re: Will the black hole of Milkomeda kill us?

Postby Chris Peterson » Tue Jan 01, 2013 4:17 pm

BDanielMayfield wrote:I have a much more optimistic take on what will happen to our planet when Andromeda and the Milky Way merge. I prefer saying merge over the word collide when speaking of galactic encounters, since with the vast distances between them (excepting dense clusters) stars will almost never collide.

Stars don't collide, but certainly, galaxies do. And these are not gentle events, even if they appear slow and stately by human time scales. Galactic collisions rip apart the structure of both galaxies involved, dramatically and permanently changing their morphologies. They produce tidal forces that alter the orbits of countless planets around their stars, and hurl countless others out of their stellar systems completely. They are responsible for massive areas of shocked gas where nebulas collide, and consequently for huge regions of star formation- which in itself produces massive, short-lived, violently dying stars, themselves responsible for altering large areas. No, I'd have to say "collision" is a pretty good word here!

In fact, simulations of what will occur around our own star are essentially meaningless, since we can't say with much precision where we'll be in the Milky Way in 4 billion years, we can't say whether a dense M31 structure like an arm will pass through wherever we are or not, and the uncertainties on the proper motion measurements of Andromeda are still much too high to even know just how the galaxies will come together (the paper takes the nominal motion of Andromeda, but there is a wide range of error). Of course, it's really academic given that Earth will be nothing but a rocky cinder by then, and if the descendents of humans survive anywhere, they will be so far removed genetically from us that to call them "human" at all would be silly.
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Re: Will the black hole of Milkomeda kill us?

Postby BDanielMayfield » Fri Jan 25, 2013 6:39 am

I find nothing to disagree with in your first paragraph Chris. Creation is often a violent process, whatever it's cause may be.

But in your last paragraph you say that the earth will be a cinder before the collision starts in 4 BY. You seem to be forecasting the sun's red giant stage much sooner than most astronomers predict. I've often read things like 'the sun is 4.6 billion years into it's 10 billion year lifetime on the main sequence.' That would have the sun's predicted Red Giant phase starting more than a billion years AFTER the big galactic collision starts.

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Re: Will the black hole of Milkomeda kill us?

Postby Chris Peterson » Fri Jan 25, 2013 3:10 pm

BDanielMayfield wrote:But in your last paragraph you say that the earth will be a cinder before the collision starts in 4 BY. You seem to be forecasting the sun's red giant stage much sooner than most astronomers predict.

No, I wasn't referring to that. The Sun is getting hotter, and we're nearing the end for most (perhaps all) life on Earth. In only another 500-1000 million years, all the water will have been boiled off our planet's surface. If our descendents are still around, they almost certainly will be living elsewhere by then, because Earth won't be a viable option.
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Re: Will the black hole of Milkomeda kill us?

Postby Beyond » Fri Jan 25, 2013 4:56 pm

Well... i can tell this thread will be 'milked' for all it's worth. :mrgreen:
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Re: Will the black hole of Milkomeda kill us?

Postby neufer » Fri Jan 25, 2013 5:06 pm

Beyond wrote:
Well... i can tell this thread will be 'milked' for all it's worth. :mrgreen:
http://petslady.com/articles/are_domest ... _man_61392 wrote:
Are Domestic Dogs Evolving Faster Than Man?
Posted January 25th, 2013 by Ron Callari

<<When you look back over the last millennium, it's hard to say if man has evolved? Homo sapiens, the forerunner of anatomically modern humans, evolved between 400,000 and 250,000 years ago. Whereas the lineage of domesticated dogs from wolves is estimated to have occurred only 15,000 years back.

Journalist and physician David Brown writes in the Washington Post that a change in diet might have accelerated the canine evolutionary process. "Your dog’s willingness to eat (dog biscuits made from wheat), instead of going for a bone in your thigh, helps explain how its ancestors evolved from wolves into house pets," he says.

Swedish researchers have uncovered some very interesting evolutionary changes in Dogs lovin' starch!Dogs lovin' starch!comparing the genomes of wolves and dogs. By pet owners feeding dogs starches instead of meat, dogs have quickly evolved from their "pack-hunting carnivore" predilection to home and hearth companions.

In Mark Derr's book, "How The Dog Became The Dog," he believes that the changes started to occur in the eighteenth century, when humans began the drive to exercise full control over dogs to complete the domestication process of its wolf ancestors.

The findings in Nature, an international science journal supports the hypothesis that dogs evolving from wolves allowed interactions with man when they began to search out food sources in refuse on the outskirts of human settlements. An alternate theory is that wolves were captured by hunter-gatherers, who tamed, bred and eventually settled down with them.

In either event, archaeological remains reveal dogs and humans have shared the same graves dating back 11,000 years ago, at the dawn of man shifting from a hunting to an agrarian society.

"Accompanying the dietary change — and probably evolving along with it," notes Brown — were behavioral adaptations that allowed dogs to tolerate man who ultimately become their masters. Additionally, the Swedish researchers found strong evidence of genetic differences in brain function — and particularly brain development — between wolves and dogs, which they have not yet analyzed.

In Moscow, dog evolution has taken yet another turn. According to Stuart Fox who writes for POPSCI, in his report titled, "Moscow's Stray Dogs Evolving Greater Intelligence, Including a Mastery of the Subway," he suggests that "the fierce pressure of urban living has driven dogs to evolve (back to) some wolf-like traits (displaying) increased intelligence, and even the ability to navigate the subway."

Relying on scraps of food from commuters, "the beggar dogs" as Fox describes them, not only recognize which humans are most likely to give them something to eat, but have evolved to actually becoming commuters on the subway. Using scents, and the ability to recognize the train conductors for different stops, they incorporate many stations into their territories and daily journeys.

Evolution has perhaps propelled Darwin's theory of natural selection in these cases. Since most of the strays take to the streets as rejected house pets, they either need to learn to thrive in the harsh realities of urban living or die from neglect. Reversing the domestication process somewhat, these dogs revert back to their primal instincts, where the fittest ultimately have the best shot at surviving.

So whether or not, dogs are evolving faster than man, it does appear they've learned when to be cooperative and when to fend for themselves -- something man has had a harder time in dealing with, particularly in times of crisis. According to Brown, it might also explain why dogs still remain man's best friend. "They grew up together," he says. I would take this one step further and say, there's still a few new tricks we can learn from those old dogs!>>
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Re: Will the black hole of Milkomeda kill us?

Postby Beyond » Fri Jan 25, 2013 8:09 pm

Beyond wrote:Well... i can tell this thread will be 'milked' for all it's worth. :mrgreen:

I didn't think of it also going to the dogs. :puppy: . I guess neufer has a 'bone' to pick with Milkomeda. :lol2:
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