View Full Version : Can galactic wind explain the accelerating divergence of galaxies?

David Stein
2012-Apr-15, 02:25 PM
I understand that a given galaxy radiates a wind of energetic particles, and that much of this wind is the resultant of the
billions of stellar winds radiating from stars comprising the galaxy. And we know that the particles from a stellar or solar wind have sufficient mass and momentum to propel and accelerate a physical object (e.g. a solar sailing ship).

So, my question is: Is it possible that these galactic winds are partly, if not entirely, responsible for the divergent motion of galaxies? And for the gradual acceleration of that divergent motion?

In mainstream cosmology, the observed divergent motion is used to argue for the origin of the Universe in a Big Bang. Just run the divergence backwards in time, the argument goes, and you arrive at a timeless spaceless infinitesimal point of infinite density. And then, for unexplained reasons, the explosion, the unfurling of spacetime.

But instead of running the universal divergence backwards to one single point, and one Big Bang, wouldn't it be just as logical to run it backwards to the centers of myriad galaxies and myriad little bangs?

2012-Apr-15, 02:57 PM
... Is it possible that these galactic winds are partly, if not entirely, responsible for the divergent motion of galaxies? And for the gradual acceleration of that divergent motion?...

Welcome David, glad to have you here.

If I understand your question correctly, you are asking if galactic winds can be the cause of universal expansion. If that is your question, the answer is no. You describe a solar sail as part of your justification for the question, but I'd like to point out that solar sails require a high surface area to mass ration to work even very close to a star, and the sail itself must be a single bound object. Neither of these properties can be attributed to a galaxy, especially one that is 80-90% dark matter.

Also, looking at it another way, the total amount of energy conveyed by galactic winds if a small fraction of a percent of the energy associated with the cosmic expansion.

2012-Apr-15, 03:02 PM
No it is not possible. The winds are too weak and the expansion to homogeneous for that. Galactic distributions are very clumpy and there is no evidence of that in the expansion.

Plus the Big Bang theory does not go back to the 'point of infinite density' - it describes the evolution of the observable universe from a hot dense state of finite size. At this point our physics models break down thanks to the problems reconciling quantum theory and gravity. We need more info to model what was happening further back.

Jeff Root
2012-Apr-15, 11:03 PM
Hello, David!

In what direction would each galaxy need to be blown?

Think about it!

-- Jeff, in Minneapolis

Ara Pacis
2012-Apr-16, 10:19 AM
Actually, a solar sail does not use the solar wind (protons) at all. It uses light (photons). If you want to use the solar wind, you'll need a magnetic sail, and that propels you at a right angle to the direction of the wind. So, even if you invoke a magnetic sail concept, it wouldn't push things apart in that manner. Moreover, much of the solar wind (from our star) only happens to flow at 400 km/s, but galactic escape velocity (from the sun's location) is ≥ 525 km/s. So, not only would it not span the distance to the next galaxy, it wouldn't even get out of the Milky Way. There is a component of the solar wind that is faster > 750 km/s, but even a lot of that gets slowed down and stopped when it interacts with the interstellar medium. I'm not sure how much of it can actually escape a galaxy. There are galactic winds of a sort that can occur from supernovae, high-speed stellar winds from new massive stars or in jets from an active galactic nuclei (a super-massive black hole) link (http://astronomy.swin.edu.au/cosmos/G/Galactic+Winds). But jets tend to happen mostly with younger galaxies so it would not be doing much now, and they're very directional which may not fit observations of uniform expansion.

2012-Apr-16, 06:19 PM
Maybe the expansion of the galaxies themselves, would be sufficient for what we observe.

What is the rate of expansion of the Galaxy according to the theory, and what on the basis of measurements?