Look out for that galaxy! *CRASH*

[J-Sun]

NASA'S Hubble Shows Milky Way is Destined for Head-on Collision with M31 (and maybe M33, too).

"I'm Robot 976QRZ3 with your morning traffic. A three-galaxy pileup was observed in the universe today. We suggest other galaxies with business in the area divert to..."

[Vertigo]

Well it only confirms what we have long thought to be the case anyway.

So... fasten your seat belts, it may be a bumpy ride!

[Venusian Broon]

Typical!

Always happens on a bank holiday weekend.

[Metryq]

I guess someone forgot to press the clutch before redshifting. Galaxy collisions are very common.

Funny how that can happen when everything is supposed to be expanding away from everything else.

[TheEndIsNigh]

... Although it'll all be over long before that.


I don't understand why this has hit the headlines recently. I thought this was very old news.

Originally Posted by Vertigo

Well it only confirms what we have long thought to be the case anyway.

So... fasten your seat belts, it may be a bumpy ride!

Originally Posted by Metryq

I guess someone forgot to press the clutch before redshifting. Galaxy collisions are very common.

Funny how that can happen when everything is supposed to be expanding away from everything else.

Something I've always puzzled about myself. Presumably this galaxy still has a red shift. That or someone has been telling porkies about everything in the universe moving away from us: red shift in every direction being the foundation of that particular argument.

Personally I'm an advocate of the 'multiple big bang' theory. If it can happen, why can't it happen again?

[Venusian Broon]

Originally Posted by TheEndIsNigh

... Although it'll all be over long before that.

Something I've always puzzled about myself. Presumably this galaxy still has a red shift. That or someone has been telling porkies about everything in the universe moving away from us: red shift in every direction being the foundation of that particular argument.

Galaxies have feelings too - they are attracted to each other! Hence despite the continual expansion of all space that drives everything apart some will indeed move and collide together because gravity compels them to. But most are sailing off away from us.

Oh and galaxies coming together have blue shift, not red

Personally I'm an advocate of the 'multiple big bang' theory. If it can happen, why can't it happen again?

Well as long as I'm not around in the neighbourhood when it happens!


I quite liked the 'Evolutionary Multiverse Model' where a new universe is created at some point inside a black hole with universal parameters slightly different - and random - from the parent universe (pure speculation of course, no idea how the author of this model was going to test it!) Hence over, loads of occurences and cycles, universes with the propensity to generate black holes would be most numerous.

It's a bit of Russian doll existence for us, but some of the scenario's for the far future of the universe - heat death etc... are sooo depressing

[thaddeus6th]

Metryq, that's a cunning point I'd never thought of before.

Hmmm. Quite glad the Venusian Broom was around to tidy up [puntastic!] that problem.

[Venusian Broon]

Originally Posted by thaddeus6th

Metryq, that's a cunning point I'd never thought of before.

Hmmm. Quite glad the Venusian Broom was around to tidy up [puntastic!] that problem.

<Gritted teeth mode on>
Fight. The. Urge. To. Reply. With. A. Pun ...
</off>

Anyway, I appear to be meandering,

Yours,
Venusian Brook

[thaddeus6th]

Cripes, sorry, I really did misread your name.

[Vertigo]

Originally Posted by TheEndIsNigh

I don't understand why this has hit the headlines recently. I thought this was very old news.

Not quite. We have known for a long time that we might collide with Andromeda but have not been able to make accurate enough measurements to know for sure. Let's face it if we have the measurements of the relative directions of motion of the two galaxies out by even the tiniest fraction of a degree then that will mount up to a very big difference over 4 billion years.

The point of the article is, I think, that they have now made more accurate measurements that confirm we will indeed collide.

[Venusian Broon]

Originally Posted by thaddeus6th

Cripes, sorry, I really did misread your name.

No need to apologise, we shouldn't ponder morbidly about mispelling forum names.

Yours

Venusian Brood

[Metryq]

Originally Posted by Venusian Broon

will indeed move and collide together because gravity compels them to.

That's an assumption that lead to Dark Matter—matter that is completely undetectable, except by its gravitational effect on galaxy structure. And then it doesn't create any lensing effects. (Can you say "ad hoc"? More like ad hoc ptui.)

I realize plasma cosmology is on very tenuous ground, also, but no worse than the theory that gravity drives the entire universe.

Do these Hubble results say whether or not the Magellanic Clouds will be involved? 'Cause I might want to move to my vacation house there until this collision thing is over with.

[Venusian Broon]

Originally Posted by Metryq

That's an assumption that lead to Dark Matter—matter that is completely undetectable, except by its gravitational effect on galaxy structure. And then it doesn't create any lensing effects. (Can you say "ad hoc"? More like ad hoc ptui.)

I realize plasma cosmology is on very tenuous ground, also, but no worse than the theory that gravity drives the entire universe.

Do these Hubble results say whether or not the Magellanic Clouds will be involved? 'Cause I might want to move to my vacation house there until this collision thing is over with.

Not a great believer of Dark matter - currently I think it's a fudge to preserve Einstein's equations. Of course it may be true and there are vast numbers of exotic particles floating about around us not interacting very much, but my current belief would be that general relativity is wrong in some fundamental manner - (no idea what it is of course, so I'm not much help, but if I were to put a bet on it, I'd say it's something to do with black holes and singularities...)

However I'm reasonably confident that bodies with mass are attracted to each other in this universe one way or another; beliefs gained through personal experience and experimental data. And I don't need dark matter to predict that some galaxies being in close proximity to others will, if the conditions are right, move towards each other.

Of course given current experimental data, gravity really doesn't have a say in this universe, given that it appears that the rate of expansion appears to be increasing. Which gives rise to my next bugbear, the great fudge of 'Dark Energy'. Again the assumption is that General relativity can't be wrong!


BTW, what's 'plasma cosmology'? Genuinely interested* Also what does "ad hoc ptui" mean. The Scottish state school education system did not touch upon the classical languages,at least when I was going through it



* note: I'm not a complete believer of the current scientific orthodoxy, and in some cases reject it - so please don't think I'm deliberately 'toeing the party line' or deliberately opposing your remarks. I studied Physics to PhD level - although as you can probably see from my verbose, long and no doubt dull reply on the Kepler thread, bog standard QM was my speciality.

[Huttman]

Originally Posted by TheEndIsNigh

... Although it'll all be over long before that.

Um...what will be over before the Milky Way and Andromeda collide?

Originally Posted by TheEndIsNigh

Personally I'm an advocate of the 'multiple big bang' theory. If it can happen, why can't it happen again?

I used to entertain that idea until recently I learned that everything is speeding up out there. Kind of intriguing, huh?

[TheEndIsNigh]

Originally Posted by Huttman

Um...what will be over before the Milky Way and Andromeda collide?

I used to entertain that idea until recently I learned that everything is speeding up out there. Kind of intriguing, huh?

The End is Nigh. Galaxies colliding? Pah! In your dreams. The end will be a lot sooner than that!

Not sure why speeding up - by which I assume you mean, 'expanding quicker than it should', would affect your view. Multiple big bangs could happen both within and outside our current expansion. IE. there could be billions of expanding universes just over the horizon of our universe all having their 'pull' on our local expansion.

Originally Posted by Metryq

That's an assumption that lead to Dark Matter—matter that is completely undetectable, except by its gravitational effect on galaxy structure. And then it doesn't create any lensing effects. (Can you say "ad hoc"? More like ad hoc ptui.)

I realize plasma cosmology is on very tenuous ground, also, but no worse than the theory that gravity drives the entire universe.

Do these Hubble results say whether or not the Magellanic Clouds will be involved? 'Cause I might want to move to my vacation house there until this collision thing is over with.

Regarding dark matter (and expanding universes for that matter) - I did have a thought recently along the following lines.

One of the odd qualities of light is that it is invisible. I did wonder what the total weight of all the photons that have ever existed, but have not yet interacted with something.

Moving away from our local expansion are thirteen billion years worth of photons, neutrinos, alpha, and beta particles - (short lived in air but, in the absolute vacuum of inter-expansion space?) and the like. In similar vein, at any one time inter-stellar/ inter galactic space would also have 13 billion years worth of these particles criss crossing the 'emptiness', at any one instant they would form a virtual sea of 'dark matter'.

So in my theory it comes down to :-

(for photon = read all the 'invisible' particles)

What is the weight of a photon?

How many photons are emitted from a source in any one nanosecond?

How many photons have existed since the universes began?

How many photons still exist? (99% as an estimate since collisions of photons with something else is so rare - just look at our sun's output)
What is the sum total of these particles?

How does that affect the calculations re dark matter/energy?