Expanding Universe without dark energy

In summary, the concept of an expanding universe without dark energy suggests that the universe's expansion can be explained through alternative theories of gravity or modifications to general relativity, rather than relying on the existence of dark energy. This perspective explores the dynamics of cosmic expansion and seeks to address the observed acceleration of the universe without invoking the mysterious force attributed to dark energy, potentially reshaping our understanding of cosmic evolution and the fundamental laws of physics.
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takacszoltan87
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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.
 
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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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  • #3
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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FAQ: Expanding Universe without dark energy

1. What does it mean for the universe to be expanding without dark energy?

Expanding the universe without dark energy suggests that the universe is growing in size due to other mechanisms, such as the effects of gravity and the initial conditions of the Big Bang, rather than the influence of a mysterious force that counteracts gravity. This perspective challenges the current cosmological model, which includes dark energy as a significant component driving the accelerated expansion of the universe.

2. What alternative theories exist to explain the expansion of the universe without dark energy?

Alternative theories include modifications to general relativity, such as Milgrom's Modified Newtonian Dynamics (MOND), and the idea of a dynamic cosmological constant that varies over time. Other approaches involve considering the effects of inhomogeneities in the universe's structure or the possibility of extra dimensions that could influence gravitational interactions on cosmic scales.

3. How do observations of the cosmic microwave background (CMB) fit into this model?

Observations of the CMB provide crucial evidence for the early universe's conditions and its expansion history. In models without dark energy, the interpretation of CMB data may require adjustments to account for the universe's geometry and the rate of expansion. Researchers must ensure that any alternative model can still explain the uniformity and temperature fluctuations observed in the CMB.

4. What are the implications for the fate of the universe if dark energy is not involved?

If the universe is expanding without dark energy, its fate could be different from the widely accepted scenarios, such as the Big Freeze or Heat Death. Depending on the alternative model, the universe could eventually slow its expansion, leading to a Big Crunch, or it may continue to expand at a constant rate. The ultimate fate would depend on the balance of gravitational forces and the matter content of the universe.

5. How does the concept of an expanding universe without dark energy affect our understanding of cosmic evolution?

This concept challenges the current understanding of cosmic evolution by suggesting that the dynamics of the universe could be governed by different principles than those currently accepted. It invites scientists to explore new physics and reconsider the role of gravity, matter, and energy in shaping the universe's history and structure, potentially leading to new insights and discoveries in cosmology.

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