merging galaxies

[larryduane100]

I just read DiscoverMagazine's email containing blog/bad astronomy article on "smash galaxies together...for Science!"
http://blogs.discovermagazine.com/badas ... tronomy%29
Today's TPOD is about the fallacy of galaxy merger models.

Mr. Plait says 50 million galaxies have been identified by the public as part of a 'citizen science project'. Galaxy Zoo is a computer program the public can use to model galaxy collisions and change parameters to get your model to look like the actual image.
It is hard to imagine 50 million results. I also wonder if anyone involved in such a huge project has thought the galaxies might be flying apart instead of 'smashing together'. I also wonder if the strangeness of all of these mergers in an explosive "Big Bang" universe has crossed the public's mind.
I realize that a person involved in the project would be ignored if such questions were voiced but it just seems that there would be some noise about all of this.
I would like to read some of the member's thoughts on this conunbrum.
Larry

[jjohnson]

I like the attitude that ordinary citizens can contribute to science, as if the ordinary citizen gave a fig about helping or understanding science, but I do not believe that internet twiddling with "colliding galaxies" whose algorithms implicitly include dark matter will help their cause, other than creating a dependency on fooling with their galactic game rather than thinking critically about the underlying assumptions.

How close do these colliding galaxies actually get to one another? Our estimates of distances to other galaxies are based on some shaky assumptions. We have not lived long enough in observational time to observe ANY relevant motions of these 'collisions' - we only have snapshots of this superimposed galactic pair or that one, and cannot actually say that they are in the same plane or are colliding or anything. In 50 or 50 million or 50 bazillion 'colliding galaxies' show me a single observation in our entire scientific history - just one - of two star's colliding. It is like looking at one frame of a video of two objects of unknown size at an unknown distance from the camera, with smaller objects frozen in the field here and there, and concluding that "these two things are in the midst of a violent collision". Yes, there are doppler indications of rotation and careful examination may or may not reveal isophote evidence of linkage between or among various elements in the scene, but extrapolating from one frozen frame does not make a feature-length film. The only star collision images we have are created artificially as art. The Scientific American article on what would happen if a white dwarf ran through a star like our sun had no evidence from the universe at large that any two stars had ever collided. They are extrapolating from an observational record with ZERO data points. That is dangerous to do, even in mathematics! (Like "black holes"...) Given the number of stars, what are the chances that there should have been at least one observable collision in human history? Given the distance between stars, or the average volume occupied by stars in a galaxy compared with the total spatial volume encompassed by a galaxy, it is vanishingly small, even in old, dense clusters. So. If stars don't ever collide (a reasonable assumption based on the record) what makes it okay to say that galaxies collide? Galaxies occur along the big stringy thingies for a reason, and they appear to stay there and not wander out into the dark voids among those filaments. Positing high relative velocities and ignoring the idea of intrinsic (as opposed to doppler or expansion red shift is a foundational thought built on sand.

Again, it is simply whistling in the dark to assume gravity controls all, to ignore electrodynamics on these scales in a plasma universe, and on top of it all, to ex temporize by positing 'dark matter' to force the gravitational model to behave differently from how it wants to predict. It is like modeling the path of a bowling ball by assuming that the only force involved is that imparted by the bowler's arm, and that the alley is frictionless, and accounting for the observed 'hook' in the ball by saying that its rotational spin creates an invisible pushing force on the ball at right angles to its velocity vector. It might work, but it is unobservable and not repetitive and doesn't explain why the velocity vector also decelerates en route to the pins. The model ignores what is already there and imagines some other action which is claimed to be, let us say, 'dark' and therefore unobservable. It's not a valid or correct model. In non-PC terms, it is wrong, or at the least, incomplete. Or both!

You, forum dudes, and I, are citizens trying to contribute to a science. We will have no "citizen input" or "assistance" to science unless those who make galactic pinball games decide to listen to our contributions.

Don't hold your breath, but press on anyway.