How Does Gravity Balance Forces Without Mass in a Pre-Big Bang Energy Scenario?

[Mordred]

Several articles I've read describing one theory of how everything could have started from nothing. State that all the energy of nothing equals zero as gravity is negative energy. One of those articles was written by Stephen Hawkings. He also stated that quantum fluctations will always exist even with nothing. That part I had little trouble understanding. What gave me the most problem was the previous statement. This was a point that mass or matter did not exist. How would gravity balance out the other three known forces without mass?

I am on my andoid atm I'll try to find the article later on.

I also realize that the big bang theory is not intended to descibe pre big bang but merely a model to aid in our understanding of current cosmology findings

 

[Simon Bridge]

How would gravity balance out the other three known forces without mass?

Balances out energy - not force.
You'd need some way for matter to acquire mass wouldn't you? However - in general relativity (where the big bang model lives) gravity is the way space-time curves in the presence of energy - mass is only one form of energy.

I also realize that the big bang theory is not intended to describe pre big bang but merely a model to aid in our understanding of current cosmology findings

The "big bang" is the rapid expansion part... it become difficult to talk about what happens "before" that without lapsing into math.

 

[Mordred]

In several other articles all the forces were combined into one force. I can't recall which one was described as seperating first. If I recall correctly it was gravity but could be wrong on that score. The distinction of balancing energy not the forces had not occurred to me. Would it be correct to assume that when all the forces were one entity prior to the split the net forces also equals zero?

 

[Simon Bridge]

Would it be correct to assume that when all the forces were one entity prior to the split the net forces also equals zero?

"Net force" on what? How would it make sense to talk about a "net force" in the circumstances?

 

[Mordred]

yeah your right I was trying to describe the scenario where all the forces were combined and referred to that as the net force, I suppose Unitary force would be more accurate.
Keep in mind that I'm asking in relation of the theory of universe out of nothing.

That being said prebig bang there was nothing therefore no "Unitary force" would be my immediate thought however Quantum Physics argue that nothing is something in the form of Quantum fluctations.
So I was wondering during the time that the stated energy balance of the universe was zero would not the combined energy potential of that Unitary force also be zero?

Hope that's clearer

 

[Simon Bridge]

Same problem - "unitary force" on what?
I'm trying to get you to realize that the simple models you are using to visualize this sort of physics are inadequate and misleading.

QM has much to say about the energy of a vacuum ... and clarifies that what we mean by a physical vacuum is not "nothing". However - Hawking et al do suggest that quantum fluctuations could be responsible for the existence of the Universe. In this case, matter and energy spontaneously come in and out of being.

I think you'll do well to canvass the less-pop-science lectures.
http://www.openculture.com/2011/09/a_universe_from_nothing_by_lawrence_krauss.html
... I suspect this particular one is the view you are struggling with.

 

[Mordred]

Thanks that is the correct model. Seen that lecture you posted before. From your reply I can see that getting more info on the quantum fluctations would best be asked in the QM section. I have another related question to ask there anyways. On the Heisenberg uncertainty and how it relates.

 

[Simon Bridge]

In that lecture, Krauss states outright that what we have been thinking of as nothing is not nothing ...

The concepts that seem to have been giving you trouble are:
1. the difference between the physics concept of a vacuum and the mathematical concept of zero.
2. the difference between Newtonian and Einstein ideas about gravity.

I think a useful way forward for you is to think like this:
For 1. in physics, a vacuum is not (any longer) supposed to be a synonym for "nothingness" ... before the universe there was no vacuum. The big bang was not an explosion into an extent of nothingness.
For 2. You don't need matter to have gravity ... what we think of as gravity is a manifestation of the way space-time geometry changes with energy-density - matter happens to be a dense form of energy but it is not the only form of energy.

So the first one helps you think about how something can come from nothing in a, hopefully, clearer way; and the second one deals with your question about how you can have gravity without matter. Bear in mind that these descriptions are not complete and you will find yourself having to refine your seas as you delve deeper.

See you in the QM forum :)

 

[Mordred]

Thanks both points do help understand the model more accurately. I had hoped that Krausses book would have been better than the lecture you posted. However when I looked at the book it lacked too many of the essential ingrediants to make it useful to me. It will be a bit before I post in the GM section on this as I am still looking up appropriate non public media related articles lol

 

[Simon Bridge]

The book is pop-science ... better than most but still pop.
It can provide a conceptual basis to start learning from but should not be treated as anything like complete. This end of physics is hard.

I sometimes wonder if there isn't a demand for a kind of fast-track through basic physics to cosmology at the x01 level that could be better exploited...

 

[Mordred]

Considering how many laymen like myself are coming to forums such as this one. Such a book would be useful. Searching the web is more often than not misleading. Many of the various papers leave you asking which model is this or that describing. Cyclic, bubble etc etc. One book that describes in detail with the supporting math etc would be something I would buy. Unfortunately the physics books I own describe the beginnings of QM. They don't even touch cosmology other than relativity and the Big Bang. Believe me readings posts on this site for the past 2 to 3 years has taught me far more lol