# Massless Universe: Examining the Behaviour & Mass of Our Universe

• Xbehave
In summary, the Milne Model solves the problem of GR in a massless universe by proposing that the energy is released in the form of photons.
Xbehave
How would a universe with a total mass of zero behave?
By comparing the expected result for a zero mass universe, can we be sure that our universe has total mass?

A universe with zero mass, if you mean a universe where the particles are masses would be dull. There would be no interaction due to gravity as it wouldn't exist. It would also take no energy to accelerate anything to any speed at any rate of acceleration. There are just simple effect so. Without mass lot, if not most, or the physics we know would be useless or not exist.

actually i meant a universe where we exist along side negative-matter, to give a total mass of zero, but i wondered if there was a solution for general relativity in this situation more than the physical implications of the fact there could be no matter in the universe.

this is a valid question, and is tied directly to "where is the anti-matter?"

Ahhhh, right ok, makes slightly more sense.

The only issue now is if you consider this negative-matter to be anti matter then at some point anti-matter and matter will eliminate each other leaving nothing...

anti-matter is electrically the opposite of normal matter, and it can be shown that any anti-matter that collided with its particle.
this negative matter would be the gravitational opposite of normal matter, I am not sure if it would be destroy on contact with its postive-particle. but as the same processes that form galaxies would push the negative-matter out it wouldn't be found inside galaxies, only between them (or visa-versa if a galaxy was formed by negative matter). Also as neg-mass-particles and normal ones always repel each other, it would take a very energetic event to cause a colision.

But my main question was if a solution to general relativity existed for a massless universe, and if this could describe our universe?

Anti-matter is not 'negative' matter. It still has the same gravitational effect as regular matter, i.e. it attracts and is attractive to all other matter (whether 'anti' or normal). The only way to get a zero mass universe is to have nothing in it at all.

Edit: There is a solution to GR for a massless Universe (in a way) that is known as the Milne Model. Google/Wiki that if you are interested. It has nothing to do with anti-matter though.

correct wallace...
and to be more correct, when matter and anti-matter annhilate they transform in radiation energy (photons)...

marco

I bow down to superior knowledge, thinking about it now there would be a release of energy...a substantial one too...my bad. I'm just a humble electronic engineer ;)

## 1. What is a massless universe?

A massless universe is a theoretical concept in which the fundamental particles and forces have no mass. This means that they would travel at the speed of light and have no resistance to acceleration. It is a topic of interest in the field of theoretical physics and cosmology.

## 2. How would a massless universe behave differently from our current universe?

In a massless universe, the laws of physics would be significantly different. Without mass, particles would not experience gravity, making the formation of large structures like galaxies and planets impossible. Additionally, the speed of light would be the maximum achievable velocity, and there would be no concept of time dilation.

## 3. Is there any evidence for a massless universe?

Currently, there is no evidence to support the existence of a massless universe. However, some theories, such as string theory, suggest the possibility of extra dimensions where particles could exist without mass. Further research and experimentation are needed to confirm or refute these theories.

## 4. What are the implications of a massless universe for the Big Bang theory?

The Big Bang theory, which explains the origin and evolution of our universe, relies on the existence of mass and gravity. Without these forces, the timeline and events of the Big Bang would be drastically different. A massless universe would require a new theory to explain its creation and behavior.

## 5. Could a massless universe exist in reality?

At this time, there is no evidence to suggest that a massless universe could exist in reality. The laws of physics, as we currently understand them, require mass and gravity for the universe to function as it does. However, as our understanding of the universe continues to evolve, it is always possible that new discoveries could challenge our current theories.

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