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The coming collision between The Milky Way and Andromeda galaxies


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In reply to an earlier post on May 27, 2012 6:50:38 PM PDT
Last edited by the author on May 27, 2012 8:18:39 PM PDT
D. Thomas says:
I believe we're converging with Andromeda at a rate of about 130,000 mph. That's a crawl in galactic terms.

When it happens, it's unlikely that humans would feel any effect, even if life on earth survives that long.

It's also possible that our sun and its satellites could be ejected from the our galaxy, the Milky Way, by dark energy from a distant supernova. We probably wouldn't notice that either, except for a brighter star and shifts in the star map over a few hundred thousand years.

In reply to an earlier post on May 27, 2012 6:52:21 PM PDT
D. Thomas says:
You're in your element, MFEH. Absurdist science fiction.

In reply to an earlier post on May 27, 2012 6:58:06 PM PDT
Last edited by the author on May 27, 2012 7:16:13 PM PDT
D. Thomas says:
You sure would! A typical galaxy is believed to consist of a few hundred billion stars, plus trillions of other objects. Plus dark matter, of course.

A distant region of space photographed in the Hubble Deep Field study was the size of a tennis ball seen from 100 meters, in other words, a barely visible pinhead. That tiny region - which includes some of the first stars formed in the universe - contains 3000 galaxies.

Do the math, 'cause I can't.

In reply to an earlier post on May 27, 2012 7:13:10 PM PDT
Last edited by the author on May 27, 2012 7:16:28 PM PDT
D. Thomas says:
A very interesting question is why matter clumped and separated from space. At the very beginning, there was only hot plasma, not even atoms, and not a photon to be seen.

I have a feeling the answer to that question is very complicated.

In reply to an earlier post on May 27, 2012 9:44:32 PM PDT
Re D. Thomas, above: "not a photon to be seen." This does not follow. At the extremely high temperature of the big bang, one would expect a LOT of photons. Remember that the total photonic energy goes as the FOURTH POWER of the temperature.

"I have a feeling the answer to that question is very complicated." That it is, and has been studied in some detail both theoretically and by computer simulation. See Krauss [1] for more on this.

1. Krauss, A Universe from Nothing: Why There Is Something Rather than Nothing.

Posted on May 28, 2012 9:25:25 AM PDT
Rukbat says:
>At the very beginning, there was only hot plasma, not even atoms

Not even plasma. At the very beginning (t+0) there was energy. Plasma is already matter, and that came about much later.

In reply to an earlier post on May 28, 2012 10:05:57 AM PDT
barbW says:
heh, yeah, much later. A few billionths of a second.

In reply to an earlier post on May 28, 2012 10:13:24 AM PDT
barbW says:
I wrote, "It's difficult for me to visualize how so many stars formed, because a huge amount of mass must be pulled together each time."

But, taking the opposite view, so much matter was created that it's been a mystery as to why the universe is so empty today. Clues from parity and mysteries in the electro-weak breakdown have been offered as a solution, but I think a definitive answer still eludes us. Maybe Robert knows the latest..

Posted on May 28, 2012 10:28:04 AM PDT
barbW says:
We read in the wiki article that the universe will die a heat death (max entropy) after 10^150 years. The previous figure was 10,000 googol years.

In reply to an earlier post on May 28, 2012 11:31:30 AM PDT
Last edited by the author on May 28, 2012 11:31:42 AM PDT
Couldn't a humanoid race create machines that will make pockets of organized matter in the interstellar ocean of maximum entropy? Thereby avoiding entropy and allow humanoids to live forever? We are not doomed, we must persevere! The end is not near.

In reply to an earlier post on May 28, 2012 12:07:53 PM PDT
Last edited by the author on May 28, 2012 8:01:23 PM PDT
barbW says:
where would they get the energy to build anything?

Yes, if they began early, they could forestall the end by accumulating large masses, before the Big Rip becomes too powerful

from Wiki

Big Rip: 20+ billion years from now
See also: Big Rip
This scenario is possible only if the energy density of dark energy actually increases without limit over time.[citation needed] Such dark energy is called phantom energy and is unlike any known kind of energy. In this case, the expansion rate of the universe will increase without limit. Gravitationally bound systems, such as clusters of galaxies, galaxies, and ultimately the solar system will be torn apart. Eventually the expansion will be so rapid as to overcome the electromagnetic forces holding molecules and atoms together. Finally even atomic nuclei will be torn apart and the universe as we know it will end in an unusual kind of gravitational singularity. At the time of this singularity, the expansion rate of the universe will reach infinity, so that any and all forces (no matter how strong) that hold composite objects together (no matter how closely) will be overcome by this expansion, literally tearing everything apart.

In reply to an earlier post on May 28, 2012 12:56:57 PM PDT
Doctor Who says:
No. Basically every task you do could only "break even" with the entropy produced and the entropy it stopped. This is called a Carnot engine and it is the most efficient engine in principle. The problem is it is non-physical. Therefore you must lose some efficiency and your engine would not reduce more entropy than it produces.

In short the tree laws of thermodynamics are as flows (in gambling metaphor form):
1) you can't win.
2) you can't break even.
3) you can't get out of the game.

In reply to an earlier post on Jun 6, 2012 8:52:02 AM PDT
Last edited by the author on Jun 6, 2012 11:35:59 AM PDT
Jeff Marzano says:
The universe is a dangerous place. It's an interesting discussion about what could happen in space to end our world.

Recently a star that is 140 light years from Earth gave off tremendous amounts of radiation during solar flare activity. Most people have never heard of this star other than astronomers. If this star was closer to the Earth it would have ended the human race.

The dinosaur killer asteroid is probably the most dramatic scientific discovery of all time. They can see ground zero where this gigantic object collided with the Earth.

I believe I heard awhile back that a few years ago a meteor came very close to colliding with the Earth like as close as our moon. The astronomers never saw it coming because it came in from the direction where the sun is.

There's been other extinction events in the distant past including the Permian Mass Extinction back 250 million years ago. That event took a long time to develop and was according to the current theories caused by volcanic activity that started in what is now Russia and lasted for a million years. This created a greenhouse gas effect.

Going back even farther in time people think some sort of gamma ray burst or some burst of deadly radiation wiped out the trilobites and other ancient sea creatures.

There's a theory out there now about the red dwarf Nemesis, our sun's evil twin star which hangs out in the Oort cloud. Every 26 million years Nemesis perturbs the orbit of comets and sends them smashing into to Earth. That's the theory anyway although even the theory's creator agrees that it must remain controversial until it can be proven which they are working on now with a new type of telescope. They think there's also a gigantic planet hidden out there in the Oort cloud.

Solar flares. Black holes. Asteroids. Gamma ray bursts. Who knows what might get us.

Jeff Marzano

In reply to an earlier post on Jun 6, 2012 2:05:28 PM PDT
Lj3d says:
Jeff Marzano says: Recently a star that is 140 light years from Earth gave off tremendous amounts of radiation during solar flare activity. Most people have never heard of this star other than astronomers. If this star was closer to the Earth it would have ended the human race.

Lj3d: GRBs or hypernova events would also cause mass extinction on earth depending on their distance from us. Even a supernova would put out sufficient radiation to eliminate most life on earth if its close enough relatively speaking.

Jeff Marzano says: The dinosaur killer asteroid is probably the most dramatic scientific discovery of all time. They can see ground zero where this gigantic object collided with the Earth.

Lj3d: Ground zero for this event is Chicxulub crater on or near the Yucatan Peninsula in the gulf of Mexico. While it is still one of several theories to explain mass extinction, it is the best theory of the pack.

Jeff Marzano says: I believe I heard awhile back that a few years ago a meteor came very close to colliding with the Earth like as close as our moon. The astronomers never saw it coming because it came in from the direction where the sun is.

Lj3d: True, and its happened more than once. I don't recall the specifics of each report, but I recall we were not made aware of the potential danger until after it had passed. This has been going on for ages. Our technology has only recently become refined enough to spot more and more potential dangers than ever before. That's a good thing as long as we spot it before being done in.

Jeff Marzano says: There's been other extinction events in the distant past including the Permian Mass Extinction back 250 million years ago. That event took a long time to develop and was according to the current theories caused by volcanic activity that started in what is now Russia and lasted for a million years. This created a greenhouse gas effect. Going back even farther in time people think some sort of gamma ray burst or some burst of deadly radiation wiped out the trilobites and other ancient sea creatures.

Lj3d: Interesting theories and ones that do shed light on what can happen to us in modern times. It also is a telling story about how, despite our technology, there are possible extinction event phenomenon for which we have no way of stopping.

Jeff Marzano says: There's a theory out there now about the red dwarf Nemesis, our sun's evil twin star which hangs out in the Oort cloud. Every 26 million years Nemesis perturbs the orbit of comets and sends them smashing into to Earth. That's the theory anyway although even the theory's creator agrees that it must remain controversial until it can be proven which they are working on now with a new type of telescope. They think there's also a gigantic planet hidden out there in the Oort cloud.

Solar flares. Black holes. Asteroids. Gamma ray bursts. Who knows what might get us.

Lj3d: Its been that way since the beginning of human existence and before. Its interesting to speculate on, but not much we can do about stopping some of these events such as GRBs, from occurring.

In reply to an earlier post on Jun 7, 2012 7:05:09 AM PDT
barbW says:
"There's a theory out there now about the red dwarf Nemesis, our sun's evil twin star which hangs out in the Oort cloud. Every 26 million years Nemesis perturbs the orbit of comets and sends them smashing into to Earth. That's the theory anyway although even the theory's creator agrees that it must remain controversial until it can be proven which they are working on now with a new type of telescope. They think there's also a gigantic planet hidden out there in the Oort cloud."

A red dwarf is a star. We observe these over 50 light years away. Here's a list for within 10 parsecs;

http://www.solstation.com/stars/pc10rds.htm

The idea that a rogue planet can form outside of a star system, or escape a star system and then move toward our system is a very improbable concept. We could catch up with a brown or a black dwarf if they were heading the 'wrong' way (because some have violent histories), but imagine how long it would take Pluto to reach Earth if it was heading our way and these imagined objects are much farther out, and they'd have to be aimed right at us..

The 26 to 33 million periodicity seen in the fossil record has been seriously discussed in papers. It's suggested to be a result of our motion up and down through the mid-plane of our galaxy, because there could be some increased jostling of proto-comets out of their large orbits with the changing gravitational effects.

Also, as we reach the top of our curve, we're hit with more gamma rays from the intergalactic emissions, since we're no longer protected by the debris in the mid-plane. They think they see the resulting increased mutation rates in the fossil record with the same periodicity.

In reply to an earlier post on Jun 8, 2012 11:12:48 AM PDT
Charlie T. says:
In reply to your post on May 19, 2012 7:45:52 AM PDT
?????

Asteroids are nearby and could hit the Earth. The spaces between stars are enormously much bigger.

In reply to an earlier post on Jun 8, 2012 11:27:21 AM PDT
D. Thomas says:
I dunno. I wonder about that, too. After all, it's expected to take place in a mere two billion years. Why... that's practically next week!

In reply to an earlier post on Jun 8, 2012 11:34:13 AM PDT
D. Thomas says:
What would be interesting would be to watch the struggle at their event horizons BEFORE they collided. But in the end, they'd simply join into a supremely supermassive black hole. That BH would REALLY suck!

In reply to an earlier post on Jun 8, 2012 11:41:12 AM PDT
Last edited by the author on Jun 8, 2012 12:46:24 PM PDT
D. Thomas says:
Is there something remarkable about radiation levels in the Andromeda galaxy? I doubt it. On a large scale, radiation levels are uniform throughout the universe.

Two billion years hence, there may be unfriendly civilizations in the Milky Way. For all we know, they may be here already. Take the Republican Party, for example, and its nativist animosity toward aliens.

In reply to an earlier post on Jun 8, 2012 12:39:23 PM PDT
Last edited by the author on Jun 8, 2012 12:47:09 PM PDT
D. Thomas says:
Whups! I was off by a mere 1,900,000,000 years. Oh well, at these magnitudes, what's a billion years one way or the other?

I don't imagine the human race or anything like it will be around then. But if we are, those Andromedans had better watch out!

Edit: According to the Wiki page on the Andromeda Galaxy, "The Andromeda Galaxy and the Milky Way are expected to collide in 3.75 billion years." So at 2 bn, I was even further off, but in the other direction.

In reply to an earlier post on Jun 8, 2012 1:27:22 PM PDT
D. Thomas,

Yours: "... a supremely supermassive black hole."

Mine: I've read, I think in Scientific American, that there may be a mass limit on black holes. I don't recall what's expected to happen when that limit has been surpassed.
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Discussion in:  Science forum
Participants:  25
Total posts:  96
Initial post:  May 18, 2012
Latest post:  Jun 8, 2012

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