I Expanding Universe without dark energy

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The discussion explores the concept of an expanding universe without dark energy, suggesting that stars might move apart like a balloon in a vacuum. While distant galaxies do move away from each other, models without dark energy fail to match the observed expansion of the universe. The consensus is that dark energy is necessary to explain the current expansion profile. The analogy of a balloon is critiqued, as there is no pressure in a vacuum to drive such movement. Ultimately, while the idea is intriguing, it does not align with scientific observations.
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Question of a noob.
Dear all!

I'm not a scientist, but I'm thinking about something, I'm curious, is it possible to believe that our universe is in a vacuum, the stars are moving away a not because of the dark energy but becouse it behave like a luffbaloon in a vacoom. Sorry for noob questions.
 
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The stars don't move away. Only distant galaxies do.

Yes, they move apart even in models without dark energy. However, no matter how you play around with the mix of matter and radiation in the model universe you cannot get the expansion profile to match the universe we see around us. To get what we see you have to add dark energy to the models.

So although you can have an expanding universe without dark energy, it does not appear to be the one we live in.
 
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takacszoltan87 said:
becouse it behave like a luffbaloon in a vacoom
That behavior is driven by the pressure of the gas inside a balloon. In a vacuum there is no pressure between stars and other celestial objects that aren't effectively in contact with each other, and there is no material outer boundary to press against.
 
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takacszoltan87 said:
TL;DR Summary: Question of a noob.

Dear all!

I'm not a scientist, but I'm thinking about something, I'm curious, is it possible to believe that our universe is in a vacuum, the stars are moving away a not because of the dark energy but becouse it behave like a luffbaloon in a vacoom. Sorry for noob questions.
Okay, Thank you very much for everyone, it make sense!
 

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