In the explanation of the expansion of the universe. Which one: Dark energy or Multiverse?

Question

"Our universe is expanding faster and faster" Saul Perlmutter - Nobel Prizes winner for physics.

There's a theory said that Dark energy is causing the expansion of the universe. For me, this is complicated & fragile theory. Let me explain:

Ok now, someone suggested that there are many universes out there & our universe is just 1 of them. The multiverse concept was first suggested by the American philosopher and psychologist William James in 1895 many years before Einstein Relativity Theory suggested. Now suppose there is a 10 year old kid who heard the multiverse concept. If he has some basic gravity knowledge + imagination, he can answer the above question easily. That is:

There is other bigger universes close to us that has greater gravity forces & that cause our universe to expand. So elegant & simple explanation.!!!

Some scientists said Multiverse is useless cos no one can prove there other universe & then they keep follow the Dark energy theory which, in my opinion, is a very weak theory to explain why universe is expanding at faster & faster rate.

"As skeptical as I am, I think the contemplation of the multiverse is an excellent opportunity to reflect on the nature of science and on the ultimate nature of existence: why we are here… In looking at this concept, we need an open mind, though not too open. It is a delicate path to tread. Parallel universes may or may not exist; the case is unproved. We are going to have to live with that uncertainty. Nothing is wrong with scientifically based philosophical speculation, which is what multiverse proposals are. But we should name it for what it is." wiki
— George Ellis, Scientific American, Does the Multiverse Really Exist?

"A common feature of all four multiverse levels is that the simplest and arguably most elegant theory involves parallel universes by default. To deny the existence of those universes, one needs to complicate the theory by adding experimentally unsupported processes and ad hoc postulates: finite space, wave function collapse and ontological asymmetry. Our judgment therefore comes down to which we find more wasteful and inelegant: many worlds or many words. Perhaps we will gradually get used to the weird ways of our cosmos and find its strangeness to be part of its charm." wiki
Max Tegmark - a Swedish-American cosmologist

What is your opinion?

Answer 1

"For long time, scientist's trying to answer the question why our universe keeps expand faster & faster?."



Net production of entropy.



"People said that it's cos of dark energy that we can't see. For me, this is complicated & fragile theory."



It isn't a theory. Dark Energy is another name for the cosmological constant. It is a way of describing the Universe displayed. So it is neither complicated, nor fragile.



"Some scientist said Multiverse is useless cos no one can prove there other universe."



It is not a matter of "prove", but of "disprove". They have no observables, so they cannot disprove, therefore it is not Science.



"What is your opinion?"



Wasted effort.

Answer 2

I think the answer lies a lot in dark matter. If we look at the amount of gravity acting within the universe we end up getting a lot more than what we can account for, therefore, there must be something out there we cannot see that is acting upon our universe. I think this in some way explains the expansion of the universe, how I am not sure it is still a mystery of the universe. Perhaps the dark matter behaves opposite and pushes instead of pulls, but this is probably completely wrong.



On the multiverse subject, I really don't believe in such a thing. If there is other universes out there I don't think ours and them interact in any way.

Answer 3

Dark energy.