Guess all I can do is ask again, simply stated … did Einstein propose or not propose a “static” model of the universe very shortly after the release of his General Theory?
However, this isn’t necessarily pertinent to question of colliding galaxies or the question here … but the new franchise expansion is fasinating.
Is it your proposal that 1) a separate galaxy could “form” within a galaxy (an oxymoron?) and/or 2) if a galaxy forms between existing galaxies, with existing matter, it could change the Hubble expansion model, e.g. galaxies colliding and/or 3) a psuedo big bang occurs creates a new galaxy and matter which would change the Hubble expansion model …
I too want to know if Andromeda galaxy is going to collide with the Milky Way? Shouldn’t this be able to be empirically proven? and 2) if this is really going to occur, wouldn’t this put hole in the Hubble expansion model? …
He changed his original formula to match the current view of the universe–which was static. He added the cosmological constant because everyone thought the universe was static. So, from that perspective, he didn’t propose a static universe–he just accepted it.
Like Chronos said, if the Milky Way already consumed another galaxy (which it probably has), then the other galaxy wouldn’t have a name (it’s long gone).
In my earlier post, I mentioned the “Large Magellanic Cloud” and the “Small Magellanic Cloud”…these are two small galaxies which are our closest galactic neighbors. I’m not sure if they are colliding with the Milky Way now, but if not, they probably will eventually. BTW, these two galaxies are only really visible from the Southern Hemisphere.
All galaxies formed at about the same time. New galaxies are not formed today–all we can see is already-existing galaxies interacting.
Either Andromeda will hit the Milky Way, or it will go past us–it won’t be carried away from us by the cosmological expansion.
And, once again, NO, that doesn’t put a “hole” in the expansion model. Hubble’s law is a simple empirical relation between distance and velocity, and you must understand that it cannot be applied over short distances. Hubble’s law was never meant to be valid over short distances; Edwin Hubble was well aware the Andromeda is moving toward us. I do not think of this as a “hole” but you might be using the word in a different way. What I mean is that it does not invalidate Hubble’s Law or the Big Bang model.
It is entirely possible for collisions to occur in spite of cosmological expansion because gravity can overcome the expansion over short distance. It’s incorrect to say that the Big Bang model implies that all galaxies always recede from each other no matter what. That’s just not what it says.
I’m sorry that I haven’t provided the calculation I promised, but I’m hesitant to do so if it will ultimately prove meaningless–I don’t want to solidify anyone’s misconceptions (including my own ).
Hi Podkayne, when Hubble made his observations he could only observer galaxies within 2.5 Mpc!! This is an extremely short distance compared to current observations. The concept that short distance gravitational effects now make Hubble’s model invalid is completely contrary to Hubble’s own very short distance observational basis when developing his expansion model. By the way how far away is the Andromeda Galaxy? Thanks …
Good research Phobos , and I agree with this as a maybe the first fact! So Andromeda was in the range of what Hubble observing, 2.5 Mpc? Do you think he missed Andromeda when developing his expansion theory, given that it is the closet galaxy, and pretty big by the way, to the Milky Way? Thanks … Andi
Yes, Hubble was very restricted in the range of galaxies he observed, but then again, the data he got out of his measurements wasn’t the best, either. He had enough to say in a vague way that allowing for some variation in the velocities, more distant galaxies are receding faster. If you look at a plot of recession velocity vs. distance for the galaxies he observed, it’ll look mostly like a scattering of points, but a scattering of points with somewhat of a bias. The scatter becomes much less significant as the distances and velocities involved become larger, so we have a much better handle on it than he did.
Hubble didn’t manage to “miss” the Andromeda galaxy–did you miss where I told you that he’d measured Andromeda’s blueshift? He identified Cepheid variables in Andromeda, which allowed him to compute its distance–incorrectly, as it turns out. He didn’t get it right because he wasn’t aware that there are two types of Cepheids, and this confusion threw off his own values of the Hubble constant (around 500 km/s/Mpc). Nevertheless, his distance to Andromeda was an important observational proof that the “spiral nebulae” lie outside of the Milky Way.
In his first paper on the subject, “A Relation Between Distance and Radial Velocity Among Extra-Galactic Nebulae,” Hubble used galaxies out to what he thought was 2 Mpc, due to his confusion of the two types of Cepheids, but these days we know it was more like 20 Mpc. Hubble’s law is certainly applicable over that length scale. As time went on, he made futher observations of more distant galaxies as well.
In any event, regardless of what distances Hubble was (or thought he was) dealing with, it remains true that for almost every galaxy whose distance is known and sufficiently large, Hubble’s law applies. Otherwise, nobody would bother with it!
Hi Chronos … you’ve been great, and this is only done out of the highest regard and for argumentative purposes only. Still these issues are close to the issues of this OP.
I agree that both Einstein and Hubble had restrictions on their incredible postulates during their times. But I was told that it was my personal view of Hubble’s expansion model that galaxies move away from each other. Hubble is very specific that “galaxies” move away from each other. Einstein postulated a “static” universe after the release of his General Theory in approx 1916, and I was told that he never excluded a expansive universe? If they’re wrong, let’s correct them, I’m sure they wouldn’t mind … Anyways …
I still believe that there must be some valid expansive and gravitational attraction models. The question still is, will the Andronmeda and the Milky Way galaxies collide? Maybe even the probability that they will collide will suffice? What are the models used to predict this collision, i.e. and does it involve Hubble, Newton, Lorentz, or newer concepts, etc?
For the question of whether our galaxy and M31 (the Andromeda galaxy) will collide, simple Newtonian physics will do just fine. The problem is a lack of data. We can easily determine the radial component of the relative velocity using the Doppler shift, and that tells us that the two galaxies are getting closer together. What we don’t know is the transverse velocity. We could, in principle, measure that by looking at the position of M31 in the sky, waiting a while, and looking at it again: If it’s in exactly the same place in the sky, then it’s heading straight for us, and we’ll collide. On the other hand, if it appears to move in the sky, then it’ll just pass us by. Unfortunately, the proper motion of anything in the sky is awfully low, espescially for something so far away, so we’d have to wait centuries between our measurements to be able to tell if it’s heading for us or not.
On the other hand, we can estimate the amount of time it would take for the two galaxies to make a complete orbit around each other, and I’m pretty sure that this is shorter than the ages of the galaxies. This means that if they were going to collide, they already would have done so several times, and there’s no evidence that they have.
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