'A Universe From Nothing' by Lawrence Krauss, AAI 2009

Schlofster

Well, I have transcribed some relevant sections of the talk, and it seems to me that my bewilderment by his contradictions is not irrational.

time index: 19:35
what could contribute a term like this, and we know the answer - nothing - by "nothing", I don't mean nothing, I mean nothing.
If you take empty space, and that means get rid of all the particles, all the radiation, absolutely everything,
so there is nothing there, if that nothing weighs something, then it contributes a term like this.


time index: 21:20
It turns out, most of the mass of the proton comes not from the quarks within the proton, but from the empty space between the quarks.
these fields produce about 90% of the mass of the proton, and since protons and neutrons are the dominant stuff in your body,
empty space is responsible for 90% of your mass.

time index: 23:48
we should test what the energy of empty space is, how do we do that? well we 'weigh' the universe,
how do we do that? well we stand on the shoulders of giants.

time index: 24:53
and the point is, we can use gravity to 'weigh' the universe including the weight of empty space

time index: 25:30
and an open universe would be infinite in spatial extent, as would a flat universe

time index: 40:20
but just like Goldilocks, in a flat universe, it is just right, in fact it is right now we know to an accuracy of better than 1 percent.
The universe is flat, it has zero total energy, and it could have begun from nothing, and I have written a piece,
although of course, I got a lot of hate mail, saying that in my mind, this answers this crazy question that religious people keep throwing out
which is: "Why is there something rather than nothing", the answer is: there had to be, if you have nothing in quantum mechanics, you will
always get something, it is that simple, it doesn't convince any of those people, but it is true.

time index: 41:01
Now, great, we know the universe is flat, but if you have been awake, 10 minutes ago I proved that the universe is open,
there is only 30% of the stuff in the universe needed to make it flat, where's that other 70%?
Well, if you put energy in empty space, so that empty space weighed something, you wouldn't see it, it is the empty space between the galaxies,
you're far away from those galaxies, you wouldn't see it.
But what would that empty space do if you put energy in it, well, produce a cosmological constant, that would cause the expansion of the universe
not to slow down over time, as any sensible universe would do, but to speed up over time.
In 1998, people measuring these supernovae at large distances to measure the Hubble diagram tried to measure what was happening at large distances
to see if the universe was slowing, well they all knew that the universe was slowing down, they wanted to measure how much.
This doesn't look like much, but it was a revolution in cosmology.
I can draw a straight line through that dataset there and bring the whole thing down and make it horizontal, and if the universe was slowing down,
these distant supernovae should have followed this curve.
Much to the surprise of the observers, the supernovae lay above the straight line, and the only way to explain this, well there is two ways,
either the data is wrong , which it usually is, or the universe is accelerating, speeding up.
And if just for fun, one believed it was speeding up, and one asked just how much energy would you have to put in empty space to make it speed up
by the amount we measure it, it is exactly the amount we are missing.
Everything holds together, our new picture of cosmology is that we live in a universe dominated by nothing.
The largest energy in the universe, 70% of the energy in the universe, resides in empty space, and we don't have the slightest idea why it is there.


A comment by Marcus seems appropriate to me:
As far as I can see, it is not only scientifically sloppy, it is more broadly logically sloppy (the little matter of whether the universe is infinite in spatial extent is muddled here).
I understand that it is impossible to express the mathematical model in natural language while still maintaining logical consistency, but I feel that in this case, no attempt should be made, because it damages his reputation and the reputation of science in general in the eyes of non scientists.

Ich

And where's the contradiction? Where does he claim that the universe has a finite mass?
"we 'weigh' the universe" - is that the phrase which bothers you?

Bob_for_short

I voted "Yes" meaning the Minkowski space-time with the gravitational filed to be physical one similar to other physical fields rather than variable curvature of the Riemann space-time where not additive conservation laws are possible.

Schlofster

what I said is that most of the mass of protons and neutrons can be attributed to virtual particles.. it is that mass that we can calculate using the theory of the strong interaction and powerful computers..

_______________________________
Lawrence M. Krauss
Foundation Professor
Director, Origins Initiative
Co-Director, Cosmology Initiative
ARIZONA STATE UNIVERSITY
College of Liberal Arts and Sciences
School of Earth and Space Exploration
http://krauss.faculty.asu.edu

On Nov 3, 2009, at 5:04 PM, Jessica Lee wrote:


------ Forwarded Message
Date: Wed, 28 Oct 2009 06:48:23 -0700
Subject: A Question For Prof Krauss.


Hi Jessica,
Please could I ask you to send this question on to Prof. Krauss?

Hi Prof Krauss,
I loved your recent public lecture <http://www.youtube.com/watch?v=7ImvlS8PLIo> at AAI 2009, but I don't understand something,

and I was hoping that you might be able to spare a few moments to clear it up for me.

First of all let me state that I am no physicist, so I am rather certain that my
misunderstanding is due to an incomplete grasp of the mathematical model that you
attempt to describe in natural language. I do understand that it is actually impossible to
do this since the mathematical model cannot be expressed in natural language.

In the lecture you say that you have calculated the mass of the universe, and have calculated that
most of the mass in the universe is as a result of virtual particles "popping in and out of existence" in empty space,
while matter particles constitute a very small fraction of the mass of the universe.
Considering this, and since you are able to calculate the mass of the universe to be a finite quantity,
it seems to me that a conclusion that the universe is infinite in spatial extent would be logically incompatible with a universe of finite mass.
I say this because if empty space itself constitutes most of the mass of the universe, then if the amount of empty space is infinite,
then the mass of the universe must also be infinite.

Thanks very much & kind regards,


------ End of Forwarded Message

Schlofster

Yes, it does bother me, are you saying that he measured that the 70% of the mass of the universe is caused by dark energy, but also that the mass of the universe is infinite because it is infinite in spatial extent, and therefore the mass of the dark energy is also infinite?

What also bothers me is I cant show this lecture to any theists or deists because he says:
"Why is there something rather than nothing", the answer is: there had to be, if you have nothing in quantum mechanics, you will always get something, it is that simple, it doesn't convince any of those people, but it is true.
They will just respond: where did the quantum mechanics come from?
When in reality, he has shown that there are 2 different definitions of "nothing", I think that he means the physics definition where empty space can be called "nothing", and this may be empty space in some wider reality before the universe was created in the big bang.
This would confuse the layman, because they would tend to use their own definition of nothing - which really is nothing - no empty space, no quantum field or fluctuations - literally nothing.
I think that his mixing of language here will really confuse the general public.

I know that he qualifies all of this by saying that you must not take him literally all the time because he cant express the mathematical model in natural language, but I am asking whether this kind of confusing talk in natural language is a good idea in a world where people often dismiss scientists as being biased against any deistic solutions.
(I am neither a deist nor a theist)

Ich

Basically, yes.
Read that text again with this in mind. I think you'll find that at no place he says something that can convincingly be interpreted as the mass of the universe being finite. You will also find that the wording "...of the mass of the universe..." - which could be such a hint - is yours, not his.
For the theist debate: Don't believe that physics can prove that there must be something rather than nothing. At least not yet, and maybe such a proof is impossibe. It's not the fault of the theists if they don't buy into it.

Schlofster

Thanks for clarifying that :-)

Schlofster

I was wrong - I have just given this to an intelligent, but very non mathy person, and she is glued to the screen - laughing hysterically and obviously fascinated by what science can tell you.

I have to now concede that what he is doing is very important - taking science to the masses and by making it accessible by sacrificing accuracy and coherency for in favour of creating an immersive, entertaining experience, inducing the awe and wonder in the audience that our universe is worthy of.

Chronos

Flat looks very attractive given current observational evidence. What flat means is subject to interpretation. There are a number of ways to induce this impression that are model dependent.

Ich

OTOH, curved looks very attractive, too.
Sorry, OT.

yogi

My take - while enjoyable and informative - Krauss pontificates at several places which are, as pointed out in the above posts, not yet established - in particular, the notion of an evolving infinite universe. Perhaps Asympotical Flatness leads to a spatal distension that approaches infinity at some infinite time - its hard to imagine an infinite universe that instantly sprang into being like Athena emerging full grown from the head of Zeus. Seems like Krauss has an agenda - that of selling Flat Universes.

Chronos

LOL, Ich. Curved is very comely. A lot if it has to do with philosophy and aesthetics. In a finite universe of finite age, you are inevitably faced with a choice between a unverse from nothing, or a cyclical universe. It is a difficult choice. Something from nothing seems illogical, but, so does a universe that can reincarnate itself in perpetuity - both forward and backward in time - without gaining or losing a single quark in the process.. An infinitely old and large universe, a third option, just doesn't work for me without a compelling solution to Olber's Paradox. There is also a fourth option - parallel universes. This, imo, is fairy dust until someone figures out how to detect them.

Skolon

I voted No. Why? Shortly because:
1. The BB Theory say that the Universe is not expanding in space, instead the space of Universe is expanding. At the beginning the Universe has a finite and little "amount" of space. An "outside" space doesn't exist.
2. The expansion of Universe is without center and without bounders.
3. I can't imagine a flat shape without bounders (name me a 2D flat geometrical shape without bounders and than extend it to 3D).

So, my believe is that the Universe it is flat only at our observational scale. It is like a humane eye observation of Earth shape: it just look like to be flat.

Chalnoth

A torus.

But really, I don't think anybody genuinely believes that our universe is perfectly flat. Just that it is very, very close to flat. And the generally-accepted explanation is inflation, which drives the universe to near perfect flatness in a tiny fraction of a second.

Skolon

Yes, maybe a torus is mathematically flat shape but is a strange kind: a torus shape Universe is closed (going on any direction you will finally arrive at the same point) but for each direction other "diameter" of Universe exist. So, it seems like each direction have its own properties.
In our Universe all directions seem to have the same properties, at least until now. Or I don't know well?

Chalnoth

Er, well, no. A torus is not closed in that sense. It's flat.

Closed is a statement about curvature. Whether or not the universe wraps back on itself is a statement about topology. It is perfectly possible to have a flat universe with a topology that wraps back on itself. Just as it is, in principle, possible to have a closed universe that doesn't extend far enough to wrap back on itself.

We'd be hard pressed to determine if the different directions wrapped back on one another after different distances, as long as all distances were beyond our horizon. But in any case, it's still perfectly possible that the circumference in each direction is identical.