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Physics, Astronomy & Cosmology / Re: Why are my atoms not flying apart? Please Hurry - May Have Limited Time Left
« on: 21/09/2019 18:14:23 »Okay, I'm not really worried about disintegrating. Just wanted to get your attention. I asked the following question on a more general forum and got a single, not-so-satisfactory answer. So here goes:As of this time, Atomic radii are not increasing due to the expansion of the universe. The bonds holding them togehter are stronger than the effect caused by the expansion.
If the very fabric of space is expanding, then I would assume that such expansion is resulting in increasing distances between all physical objects -- not only macroscopic objects like galaxies, but also between the very particles that make up atoms. I get that at that scale, such increases in distance would be infinitesimally minuscule -- but I also assume not zero.
My layperson understanding of particle physics tells me that the strength of the forces governing subatomic interactions are very critical -- and measured to many, many decimals of precision. Furthermore, if the constants were reduced by the even the slightest amount, one result would be that nucleonic particles would not be able to adhere (or whatever the term of art is) to form stable nuclei.
So (I'm sure you see where this is going), if the forces have remained constant, and the distances, however infinitesimally, are increasing, then at some point in the expansion of the universe, won't atoms cease to exist?
To explain, I'll use a somewhat loose analogy. Imagine you and someone else are standing on a waxed tile floor in your stocking feet, each standing in the center of am adjacent tile. The tiles all begin to expand. You and your friend will move apart. But if you grip hands, the floor will still expand but you won't move apart. The strength of your grip is stronger than the friction between your socks and floor. This is somewhat similar to what is happening with the universe expansion. The expansion, if it could, would separate adjoining atoms, but the force holding the atom together holds them in place.
This is true not only for atoms, but galaxies and groups of galaxies. The gravitational bound is stronger than the effect of the expansion and holds them together against it and keeps them from expanding along with the universe. Galaxies and groups of galaxies retain their size, while moving apart from other galaxy groups.
Now, having said that, this may not always be the case. A while back we learned that the expansion of the universe is accelerating and the that the rate at which it expands is increasing.
So let's go back to the tiled floor. If we keep increasing the rate at which the floor expands, the tendency for the soles of your feet being dragged along increases. Eventually, it will exceed the strength of your grip and you will be pulled apart.
In cosmology, this eventual result due to an ever increasing rate of expansion is call the "Big Rip".
As the rate continues to increase, the ability for structures to hold together against it begins to fail. First groups of galaxies will begin to pull apart, then later galaxies themselves will pull apart into independent star systems. Down the road, the planets of those star systems will be ripped away. Going further forward more, the planets and stars will be ripped apart as their gravity will no longer be enough to hold them together. This will continue as smaller and smaller structures succumb.
If this turns out to be the eventual fate of the universe, it turns out that the end comes fairly quickly. For one model, which has the end coming in 22 billion years, galaxies would be pulled apart ~60 million years before the end, and our solar system would hold together until just three months until the end, planets and stars wouldn't go until minutes before the end, and atoms just moments prior to the end.
And we really don't know if the the Big Rip scenario is the actual fate of the universe.
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