Galaxy Collisions: Simulation vs Observations

[MrLionHat]

What's the song?

[spider853]

Imagine you're go to the window with a cup of coffee and see planets and stars flying around and you are like: -Darling, quick, get the f*** camera! We will film this and post it online and become a millionaire! (Evil laugh)... Bang... a planet just crushed in your house :-D

[djbarryiii]

Spectacular!

[TriKri]

NIce! Really good job! :)

[ShwangShwing]

All the stopped frames match the 5 different pictures. So the pictures are pictures of galaxies in different stage of collision. That's strange... Does it mean that all the galaxies collide in the same way?

[100PercentGreen]

So is this a proof that our simulations are reasonably accurate?

[qunniq]

poor septillions of life forms dieing =(

[kelsob]

You're stupid?

[qunniq]

no one died in that collision?

[kelsob]

Assuming there is any life in the galaxy (who knows?) yes it definitely all would of died during the collision, but not because of the collision. The individual star systems within the galaxies are actually very far apart and when two galaxies merge, although their might be some collisions, they aren't commonplace. As for the life forms dieing, this happens over the course of millions of years, meaning on the time scale of our lives, we would likely not notice much change.

[qunniq]

so the answers yes i'm right your stupid

[Drag0nfoxx]

@qunniq - No, the answer is 'no'. No-one died because of that collision.

[kelsob]

good comeback!

[rochelimit55555]

@qunniq they died because they probablu live only for 100 years (if they're human). this collision happens like gazillion times longer than human lifespan

[qunniq]

@rochelimit55555

So youre saying in the span of the life of a species absolutely no one died as a result of this collision?

[rochelimit55555]

@qunniq I think it will be like apocaclyptic death at certain point when certain smaller elements of the galaxy effect the tiny relics (planets) in the collision.

if any organism would be inside where the collision happen, they probably evolute during the course of the collision. say a humanbeing will probably evolute into 5 species during the collision process. it's galactic time, something that's grand and long.

[johannesvalks]

Very nice animation!

[rothgowooft]

Awesome. But... for these galaxies to all be such a close match for different stages in the simulation, wouldn't all of those galaxies from the photo's needed to have collided in a very similar way? Kind of odd that they'd all be roughly the same velocities and relative angles. Odd.

[Flyborg]

Not quite - there are only half a dozen examples shown, and there are countless billions of galaxies to choose from. It also keeps rotating the simulation to fit the examples, since we can only see them from 1 angle. And some of them are pretty rough matches.

[rothgowooft]

Sure there appears to be billions out there, but I didn't realise there were so many nice quality galaxy collision pictures to choose from. I stand corrected.

[BlackMetalWarewolf]

@rothgowooft there are only so many ways to significantly mismatch angles betwen 2 disks.

Remember, this is one simulation of a likely collision scenario, compared to 6 out of trillions of galaxies and trillions of different collisions. finding pictures that match isn't going to be difficult. I understand what your saying, but this simulation is a mere study of behaviour, not a model of how all galaxies colide. Like car crash tests arent models of how the car will crash, just a behaviour study.

[aceboylemieux]

see when two galixies collide the litarally go strait

through each other because of the vast distance between stars in the two galixies are light years apart nothing happens except the center masses combine then the get back into shape some times the dont even combine

[Baleur]

Thats just wrong. Every single star in a galaxy is on its own course, and it will be affected by the other stars in the other galaxy as well, eventually resulting in the two galaxies combining.

[Mendelevium146]

Its true that they don't literally "collide", but the fuse due to gravity that allows every stars of each galaxies to interact with each others. But after all, nothing really "collides" in our world either, atoms just get really close to each others and never really touch when you smack something. I think this is as much of a collision as two bullets hitting one another

[TheXRealXBrapp]

@Mendelevium146 Are you saying if a punch a wall, i'm not actually touching it??

[Mendelevium146]

@TheXRealXBrapp Exactly, in fact what you feel are the molecules of the wall repealing the ones of your hand

[TheXRealXBrapp]

@Mendelevium146 Whaa?? well why would it stop so suddenly?

[Mendelevium146]

@TheXRealXBrapp because the closer they are, the stronger the force that repeals them is. Thats why the harder you hit a wall the more pain you feel in your fist.

[maplestorystudios]

this is my thought of collisions between

galaxies....

DAMN SHIT

[CACBCCCU]

The only other thing I wanted to say is "thank you" to fjsummers for finding and posting this superb video.

[fjsummers]

@CACBCCCU You're welcome. Thanks for your comments and interest. I will only note that I didn't find this video, I created it.

[CACBCCCU]

I don't know whether the initial/intermediate/final spin profiles in this sim are supposed to match the anomalously-flat spin profile curves observed in actual galaxies. I suppose they do not.

[CACBCCCU]

My remarks compare the upper galaxy in the image at 0:10 with the simulation at 0:12 --

Because a cosine factor isn't used, what should be a dark ring area navigated by two long wound-up spiral arms is simulated as a less-dark ring area navigated by numerous looser spirals.

Also, as near as I can tell, the evenly-spaced spirals in the sim could be a manifestation of patterned inhomogenaity in non-random initial conditions.

[CACBCCCU]

The spiral arms look wrong because they didn't do a low-energy quantum correction to Newtonian gravity, I believe. The correction involves simply mutlpying Newtonian gravity by a cosine with a wavelength that is on the same scale as the diameter of the galaxy. The effect is only obvious with a dense compact center mass, otherwise it is smoothed away.

[gulskjegg]

Awesome, but its s shame that theoretical even would take what, about a million years to unfold?

[fjsummers]

@gulskjegg The simulation covers about 1.5 billion years. Galaxies collide very slowly.

[lateintheday2007]

Bravo! Frank Summers animation is awesome, using existing galaxies at different times of their collisions!

[ucenigma]

very cool.

[ArizonaDelRio]

I predict this event will seriously affect an already troubled housing market.

[maccollo]

This is a NASA simulation right? Accurate like hell I say.

[fjsummers]

The computer simulation was done by two astronomers, one at Case Western Reserve University and one at Harvard University. The simulations were done to research the process of galaxy collisions, and the results have been presented in research publications, such as the Astrophysical Journal.

The visualization was also done by an astronomer, myself. A visualization takes the data from the simulation and turns it into pictures. My viz preserves the detail of the science data as much as possible.

[CheeseSample]

What program did they use to simulate this collision?

[fjsummers]

@CheeseSample To create the visualization used a C program that I wrote myself.