Why doesn't the universe collapse?
Hey!
Gravity is a fundamental force—every object and particle with a positive mass attracts each other. This includes you and a molecule on the other side of the universe. While the gravitational force weakens with distance, two questions arise:
1.) How can the universe expand against gravity? Is there such a thing as "antigravity"? After all, every force has an opposing force.
2.) Why is the universe expanding ever faster? Can this really be attributed to the energy of the Big Bang?
Best regards!
(9 votes)
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You don’t have to go to “dark energy” or anything else. that is simply a question of the initial conditions. stay in the frame of Newton’s physics. Your question would be similar “how can a ball move upwards on the earth if the gravity acts downward?” and the answer is simple: in which I threw him up. yes, the gravitation will slow him down, and yes, probably he will eventually turn around and come down, but that doesn’t mean he can’t move up. if I have thrown it fast enough (> ca. 11 km/s) it will even move away forever and ever from the earth to the infinite. only because the force of gravity acts constantly downwards means, of course, NOT that nothing can move upwards.
the attraction between the mass slows down the expansion, but that is, of course, NOT that it cannot expand.
that has nothing to do with “anti-gravitation”. consider the Newtonian mechanics again: the earth exerts an attraction on you, and you exert an exactly equal attraction on the earth (in the opposite direction). THE is the meaning of strength and strength.
because in addition to the uterus and the radiation in the university there is obviously something else that we call “dark energy” (and is still best described by a simple cosmological constant in the Einstein equations)
No. but no one has claimed that.
I don’t know, but I thought about it almost 20 years ago and came to a relatively interesting assumption.
Time is considered a measure of change, so to speak, to describe the development of entropy. Therefore, let us assume that the continuous time is also a result of the expansion of what we call universe (and yes, I deliberately formulated it in this way because I find the meaning rather unfavourable due to the term “universum”. If the expansion gradually decreases, but a certain “information imperfection” can be assumed by the limit of the speed of light, the impression of accelerated expansion is likely to arise particularly in the case of more distant objects, because their light information originates from a time of greater expansion. Interesting in this is that in astronomy one always emphasizes that some stars that we can still see in the night sky may not exist at all, just because the light of them is already as old in years as they are distant from us in light years, but it is like to fall under the table that the influences of the Doppler effect in the expansion of the universe are cling out thematically, although this is a slowdown in time. If this is so, and this is a huge if, at all, it would not really be foreseeable when the expansion finds its end, especially if the expansion trend and thus, in order to come with an even bigger one, perhaps also the time sequence will decrease, which then would prevent a waste of a eventually dead “universum” and instead (externally considered) lead to a big crunch with possible restart.
And as mentioned above, the seemingly accelerated expansion, in particular objects far away, would be rather a sign, under the assumption mentioned above, that the expansion actually leaves behind and only the age of the information of objects far away from our already slower temporal sequence would lead to a slowing in the expansion.
It should also be taken into account and was also in my assumption that, of course, the Doppler effect should increase proportionally with increasing distance. All that deviates from this could lead directly or indirectly, instead of an accelerated expansion, to a slowed expansion, even if the latter perhaps only take into account the speed of light for information propagation and possibly different speeds of time corresponding to the expansion in order to designate it in this way.
Since I have studied nothing in this regard, this can seem more or less like nonsense from the terms used, while some others may seem like nonsense, because a delay in information due to the speed of light and relativeity of time in context with entropy is rather not just everyday themes, but from the basic idea I think that this could be done as a thought experiment at least once if you have the necessary understanding, perhaps also the necessary computers.
Thank you for your answer!
I understood your answer as follows:
The expansion has already left behind, but we do not know it (still) because information needs us for a while – max. Speed of light. But if that were so, then the concentration of matter in the universe would increase, but it does not.
And time and expansion aren’t bound together? Time is independent, but relative.
PS: The Doppler effect is not ignored during expansion.
Lack of study does not prevent good, logical thoughts!
Tag: Dark energy – this is currently being intensively researched…
https://de.wikipedia.org/wiki/Dunkle_Energie
The gravitation is hardly understood, one still seeks the gravitron as a rubber band between matter.
The “dark energy” is traded as the theory of repulsion on large scales. Dark because unknown.
The “dark matter” was invented as the theory of excessive gravity within galaxies.
It’s at the beginning. That’s how the stars were born. And because everything was still in motion, the constellations that we know as galaxies and in which there is a balance of attraction and centrifugal force are found.
So you could ask: Why does the moon not crash on Earth? Or the earth in the sun?
I don’t know whoever finds out gets a Nobel prize. It is assumed that some kind of energy is responsible for this (dark energy) that drives the galaxies apart.
…. because “our” spinweb – universe of only 4.9% matter (pulse about 27% sog. Dark matter) exists where the gravity force can also act as a field property. Another (unknown) component in this equation is the so-called antigravitative “dark energy”. In addition, we know that such extremely large spaces, such as that of the universe, where there are no gravitational field strengths, expands everywhere, where this does not hold the gravity together – this expansion then sums up over the distances. Finally, each inertial system with gravitative fields acts on adjacent gravitational systems accelerating. However, it is not clear whether the entire universe expands (or at least evenly) and not only local spaces (with an extension of perhaps several million to one billion light years).
There is no “antigravity” – just as with all other fundamental forces of interaction.