Infinite Density ?

modeller | 21:08 Wed 01st May 2013 | Science

38 Answers

If the big bang started from a mass of near ' infinite ' density then the mass must have occupied a space. No matter how small that mass was it would still occupy a space. If that is the case then how can we say space did not exist .
If instead of mass could it be pure energy . Does energy require space ?
Can mass be created from pure energy alone ?

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jomifl

Vascop, Maths may have it's limitations, we just haven't found those limits yet.

Graham-W

Modeller. The most simple energy into mass reaction I can think of is Photosynthesis. Light energy, from the Sun, is converted into Biomass by photosynthesis.

jomifl

Graham, photosynthesis does not create matter from energy. It just lowers the oxidation state of the carbon in carbon dioxide.

jim360

What is "pure energy" by the way?

One physical example, though, is the non-empty vacuum. Any realistic theory requires that the vacuum be continuously creating particle and anti-particle pairs -- though they constantly vanish again. Still, it's a continuous (albeit fast) cycle of energy --> matter --> energy again.

modeller

Question Author

//Light energy, from the Sun, is converted into Biomass by photosynthesis. //
I think that is using photons to react with the mass that is already there.

Graham-W

In photosynthesis, if no energy is adsorbed to create mass, where does it go?
http://biology.clc.uc.edu/courses/bio104/photosyn.htm
Photosynthesis is the process of converting light energy to chemical energy and storing it in the bonds of sugar.

By converting light energy into chemical energy there must be an increase in mass.

Graham-W

Just read back what I put and it seems the light energy remains as energy, even though it is converted to chemical energy and stored in the sugar bonds.

modeller

Question Author

jim // Still, it's a continuous (albeit fast) cycle of energy --> matter --> energy again//

The problem there is , the result is zero energy . So there is nothing
available to create any matter . Let alone enough to create the matter required for the BB.

jim360

No, not really. Where did you get the zero energy from?

This process isn't 100% efficient -- since nothing is. Energy is lost, and gained, and lost again, and spit all over the place, and particles can split into yet other pairs... All the time, continuously.

modeller

Question Author

No I didn't mean zero energy but rather no change //energy --> matter --> energy again// The particles cancel each other out as you say simultaneously.
Either way I am still stuck with the problem of there being no space prior to the BB. Not a vacuum just nothing. But in order for the BB to occur it had to consist of something ,
did it consist of matter which would require space or particles which have zero rest mass but require space to exist.
The only other option is that there is a form of energy that is totally beyond our comprehension but nevertheless exists.

jim360

Well there is change, though, it's not really a zero-sum process.

At least some of the problem is that I don't do nearly enough cosmology to answer this. But then, you can rest assured that no-one else knows the answer either.

Peter Pedant

Graham - W ; any endothermic reaction provides an answer innit ?

(energy into mass)

in the Mg - > MgO reaction - we were taught that the mega huge energy release came from an ever so slight reduction in the atomic weights

in which case in an endothermic reaction.... the converse occurs.

just a thought - I dont do this professionally

vascop

@jim
What is a non-empty vacuum?

vascop

Is it this idea that you are refering to?
http://blog.darkbuzz.com/2013/04/nonempty-vacuum-is-not-crazy.html

jomifl

It has been suggested that 'empty'space is in fact an energy field of an unknown nature and unimaginable proportions and that all that matter is, is just standing waves/resonances within that field. If this or something like it was the case then the question of where the BB came from is relatively easy to answer. Perhaps this is what string theory refers to.
The next question is of course ...where did it all come from? I'll leave that to the theologians they can always be relied upon to come up with a convincing explanation for everything that they never thought of.

jim360

Not exactly, vascop. I was meaning rather that even in general there is no such thing as an empty vacuum -- because at a fundamental level any consistent theory of interacting particles requires that the true vacuum be very active. For an analogy (though this isn't necessarily reflective of the truth), if something has an expectation value of 0 it could still have a lot going on. Example: Normal distribution about the zero point.

In a similar way the vacuum is full of particle-anti-particle pairs appearing all the time, and these can even interact with matter passing through, and so on. The net effect I can't say for certain, because in reality we have curved space due to gravity and no-one yet knows how to work out properly what's going on in that case.