What type of nothing?
|Jan2-13, 08:32 PM||#1|
What type of nothing?
FYI I'm not a physicist (as you will soon be able to tell from my question, so my apologies :) )
I have a question regarding where the big bang came from
The big bang theory (singularity not phase) is often said to say how everything came from nothing.
Nothing is now said to be more complex than we once realised, where nothing has complex properties etc.
If the point of singularity was to explain how everything came from nothing, would it explain how everything came from the nothing of physics, or the nothing of philosophy (where nothing is a 'true' nothing)
I guess it would be the first! but no one ever clarifies. If it is the first would the physicists nothing be eternal? And outside of the universe?
Or is this complex nothing very much a part of our universe where nothing (as well as everything) was created by the big bang? Therefore suggesting that philosophical nothing was before (or rather not even nothing existed before the big bang)?
Any help would be appreciated
Thanks in advance
|Jan2-13, 09:17 PM||#2|
Do keep in mind that there are several different models of how our universe's expansion might have started. Several do not involve a "singularity" and the ones I am thinking of do not involve anything called "nothing".
these newer models are called "nonsingular" models because of not having a "singularity". The most common type of nonsingular model that researchers study currently is a "bounce" model. Expansion begins from a very high density state stemming from a collapse.
So these days when there is a cosmology conference (one of the big international ones they hold every few years) you are apt to hear talks by people about their work with bounce cosmologies. computer simulations. equations that describe the bounce etc.
I actually don't know of any professional cosmologist working today who thinks the expansion we can see going on actually began with a "singularity".
that is more pop-sci media talk, I think. You wouldn't hear it at a conference of professionals talking to each other. It is more for television.
So that's something to keep in mind. there are different math models of how expansion started and what was going on then. They make predictions of features we may be able to see in the background of ancient light (the "cmv") they have to checked to see if the predictions are right or wrong, or at least to narrow down the possibilities.
|Jan3-13, 09:19 AM||#3|
The idea of a universe from nothing as I understand iit comes in al least two main forms.There may be others too. The first was suggested by Edward Tryon who suggested the uvierse may have zero not energy and hence may be the reuslt a fluctuation from a vacuum.
The second is from Alex Velinkin who suggested that space and time themselves can tunnel into existence from a state with no space and time. This is not from a vacuum. The only thing that eixsts here is the laws of physics which somehow exists even when there is no universe.
The first idea dates back to the ealry 70's and the second to the early 80's.
In the media interest in these ideas has increased recently especially after LAwrence Krauss has publicised them. Before that it was ALan Guth who promoted them, but that was in the age before youtube.
However as Marcus pointed out intereste in these ideas seems to me to be on the decline in the professiona literature and bouncing cosmologies are on the rise. It seems to me that you are more likely to get tetsable predictiosn from the latter than the former. If you listen to Krauss's he seems to me to be suggesting that a universe form nothing must have inflated and we can look for signs of that in the CMb and we find it and hence the unvierse from nothing has some evidence for it. I dont think even he says its proven.
However a bouncing universe also undergoes inflation so I think his case is overstated.
|Jan3-13, 12:29 PM||#4|
What type of nothing?
Thanks for the responses,
I had an idea that singularity models weren't to popular, but cheers for clarifying. I still here a lot of universe from nothing talk but I guess that's Krauss and pop talk, it's also very popular with the 'God debates' (which Krauss has taken part in on rare occasions)
I have krauss' universe from nothing on my reading list, is there anything you would recommend on a bouncing universe?
|Jan3-13, 02:00 PM||#5|
Here's a search for quantum cosmology (including loop quantum cosmology) since 2009.
this is ranked by the number of citations the paper got, so the most important, most widely cited papers come first. The search picks up 434 research papers. Scanning down the first 20 or so, which are the most highly cited and so in some sense representative of the mainstream, gives an idea.
Bounce models predominate in quantum cosmology. Most of the top 50 papers, and about half of the total 400-odd.
The guy usually asked to give the quantum cosmology overview talk at major conferences is Abhay Ashtekar. You can see his name on many of the top 50 articles on that list.
Other names: Edward Wilson-Ewing, Ivan Agullo, William Nelson, Francesca Vidotto, Alex Corichi, Par Singh, David Sloan.
Either because they are too busy or for some other reason, none of these people seem to have taken the time to write a BOOK length popularization.
Ashtekar has given interviews, and has a collection of semi-popular MAGAZINE articles at his website. I could check his website and see if there are any I'd recommend. But offhand I don't know of one.
|Jan3-13, 02:46 PM||#6|
he also wrote an article that got on the front page of the Scientific American
As MArcus said Ashtekars web site is excellent , here is the link
i also recommend this, a bit more technical but not too bad.
|Jan18-13, 01:24 AM||#7|
|Jan18-13, 07:51 AM||#8|
I think what Vilenkin is asking is do the laws of physics allow for the unvierse to come into being from "nothing"? He argues the answer to that questions is yes. Of course that doesnt mean that's what really happened.
|Jan18-13, 11:07 AM||#9|
It is worthwhile noting that the 'big bang theory' describes the early evolution of the universe, NOT its actual origin. Our models start a few moments AFTER the initial start. The known laws of physics so far are not much help because they describe how things evolve in time not how time can begin.*
Wikipedia puts it this way:
A popular book on a cyclic model without math is Paul Steinhardt and Neil Turoks' book THE ENDLESS UNIVERSE
about a cycle model they developed..It is covered briefly here:
The authors say this:
and I introduced a discussion after reading the book here:
In this discussion I recall Marcus noting that the original research paper is not
widely cited, so I guess their idea never took off....
If you search these forums for things like cyclic cosmology, brane cosmology, etc, you'll
find a number of discussions.....
|Jan18-13, 12:14 PM||#10|
Oh, and someone should point you towards 'vacuum energy'....in 'empty space'...
in essence, there is no 'nothing'...there is ALWAYS something....but it is theoretical....
and maybe zero point energy if you are interested:
|big bang, nothingness|
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