How could something possibly come from nothing? He reminds me of the Sokal Affair.
They are not his theories, the idea came from a cosmologist called Alex Vilenkin and its far from new, dates back to 1982 in this paper:
Vilenkin's is one of many many ideas as to the origin of the universe, including ideas that it may be eternal. There is no consensus and certainly no observational support for any one idea
There are many, many cosmological models that attempt to explain the origin of the universe. Most recently, models from quantum gravity have grown in popularity, such as loop quantum cosmology's 'bounce' models (marcus is the expert on this, I don't know enough about LQG to comment on them). There are various cyclic models, and loads of models where the universe can fluctuate out of a vacuum.
If you're asking if Krauss's ideas are accepted to be possible, then yes. That may be how the universe began. However, there is no consensus. There are dozens of non-singular cosmologies that are researched by many people.
BTW, as pointed out by skydivephil, these aren't Krauss's ideas. Actually, Edward Tyron was the first to start taking seriously a zero-energy universe.
Krauss is IN physics academia, so obviously for at least one person the answer is yes.
Tyrons idea is the universe arose form a vacuum fluctuation. But there is still a vacuum and an underlying space time there in the first place. Vilenkin's idea has a better to claim to the word "nothing". In Vilenkin's model space and time themselves tunnel into existence from a state where there is no state or time. Vilenkin is a well respected cosmologist so i really dont htink one can compare him to the subject of the Sokal affair. But being respected and getting your stuff into proper physics journals is just the beginning of a long road to acceptance, not the end point if there ever is one. Until your model makes predictions that can be tested it wont gain full acceptance. To be fair to Krauss hes not arguing anything more than the idea is plausible, not correct.
What does the zero energy universe mean though? From what I've read on this there seem to be some formidable obstacles:
1. Energy is not a globally defined quantity in GR, so it means nothing to say the total energy is zero.
2. The simple description of the concept seems to rely on the fact that gravitational potential energy is usually presented as negative, with zero being achieved only at infinity, and offsetting this negative against the positive energy of matter and radiation. But this seems purely arbitrary, as it is only relative, not absolute levels of potential energy that have any physical meaning.
Is there any physically sound way around these objections?
Andrew, see this paper:
The total energy of closed or flat (if finite) universe sums up to zero in GR.
Krauss basically presents the mainstream view of theoretical physics within academia to the public.
Thanks for that link Mark. I see from the abstract that the paper is based on pseudo-tensors. I have avoided pseudo-tensors thus far, having gained the impression that many physicists do not consider them respectable, such as in this FAQ post. The coordinate dependence does seem to be a problem. Does the total energy, as defined by these pseudo-tensors, sum to zero in all reference frames, or only in a particular class of frames?
Thanks for the link to the FAQ.
Yes, I believe all of Berman's papers use pseudo-tensors. The energy sums to zero for only a closed universe, see from the FAQ you posted:
"For certain pseudo-tensor definitions of mass-energy, the total energy of a closed universe can be calculated, and is zero.[Berman 2009] This does not mean that "the" energy of the universe is zero, especially since our universe may not be closed."
Since he obtains the 'general relativistic version of the energy-momentum four vector' (by contracting the Einstein pseudo-tensor with the stress-energy tensor), I would assume this is independent of the FoR.
However, there is a coordinate dependence - on Cartesian coordinates. If you use spherical coordinates, there isn't any way to guarantee energy is conserved, but instead varies in time. So, you must use Cartesian coordinates. However, I seem to remember Berman writing another paper where he derived the result with spherical coordinates, but I'm not sure.
And of course, these only apply for a finite universe (closed or flat). If the universe has negative curvature, or an infinite flat topology, then of course there is no consistent way you can integrate the energy density over an infinite space and receive sensible results.
a good review at
INTRODUCTORY LECTURES ON QUANTUM COSMOLOGY
....Boundary Condition Proposals and Tunneling
Hartle and Hawking (Hartle and Hawking, 1983; Hawking 1982, 1984a), Linde (1984a, 1984b, 1984c) and Vilenkin (1982, 1983, 1984, 1985b, 1986, 1988), but there are others (see for example, Suen and Young (1989)).
Quantum Creation of the Universe
Some of the older papers on quantum creation of the universe are those of Atkatz and Pagels (1982), Brout, Englert and Gunzig (1978, 1979), Brout, Englert and Spindel (1979), Casher and Englert (1981), Gott (1982) and Tryon (1973). Various aspects of the quantum creation of the universe as a tunneling event have been explored by Goncharov et al. (1987), Grishchuk (1987), Grishchuk and Sidorov (1988, 1989), Grishchuk and Zel’dovich (1982), Lavrelashvili, Rubakov, Serebryakov and Tinyakov (1989), Lavrelashvili, Rubakov, and Tinyakov (1985), Rubakov (1984) and Rubakov and Tinyakov (1988)......
Creating a Universe in the Laboratory
The possibility of quantum creation of an inﬂationary universe in the laboratory has bee studied by Farhi et al. (1989) and Fischler et al. (1989). See also Hiscock (1987) and Sato et al. (1982)....
i asked personally to vilenkin "why exist the universe" , and he answered:
"better ask to the Dalai Lama" and we laugh a while......
how can be tested ? Quantum creation scenarios produce gravitational waves of a calculable form and magnitude, models differ in predictions
The Quantum Creation of the Universe can be Observationally Verified.
Grishchuk, L.P. (1987), Mod.Phys.Lett. A2, 631
QUANTUM EFFECTS IN COSMOLOGY
Vacuum is not nothing.
Also the situation with Krauss .....
1) as far as I can tell his peer-reviewed papers have nothing to do with quantum cosmology
2) he presents one possible scenario for the creation of the universe, but doesn't mention
that this is one of about fifty others
3) once he presents that one scenario he goes *way* overboard into theology and philosophy in ways I personally find very objectionable since it give the impression that all physicists support those views which they don't.
A lot of this depends on "theories of what?"
He gives people the impression otherwise. If that's not his intention, he needs to be much more careful.
The description from his book on Amazon says:
Personally, I find that nutty, and well beyond the data. The problem with Krauss is that not that he is a crank. The problem is that he isn't a crank. He's written some excellent papers, and if you cut out the philosophical and religious commentary, there is a decent introduction to some of the current ideas in cosmology. That's what makes this dangerous. Someone that doesn't know better can't easily separate the science from the non-science and assume that physicists agree with his religious views.
It's actually very hard to figure out what to do with Krauss. I have different religious views which are quite different to his, but I don't want to go into details because I like to keep my religion and my science separate. On the other hand, when he ends up giving people the impressions that because physicists often try to avoid talking about God, that means they are all atheists, then I just have to mention that this just isn't true.
One other problem is that Krauss doesn't emphasize the extent to which theorists are *guessing* and that what guess ends up to be the solution is based on observation. Something that could very well happen is that we see a certain CMB signature or find primordial gravity waves at which point, Krauss would have to write another book, remember what I wrote 10 years ago, well it was wrong. Not that this is a bad thing. One of the reason I find science more interesting than religion is that science tends to say "remember what we thought ten years ago. HA!!!!! it was wrong."
Once you remove the element of self-doubt, observation, and uncertainty from science, you end up with a mess.
I totally agree that a more interesting book on the early universe would include the many different scenarios, quanutm bounce, brane clash, CCC, VSL, etc . and yes I think he needs to be louder on his caveats. The model hes basically putting forward, Vilenkins tunneling form nothing model, is just one idea out of many. Nevertheless those caveats are there and I guess perhaps people read into what they want to, ignoring them or noticing them depending on what they want to see.
What I think Krauss is saying is that a quantum nucleation event from "nothing" has to have undergone inflation to get the unvierse we see. The evidence points to inflation and so his scenario is "more plausible", I dont think he ever claims its verfied. My problem is that a bouncing unvierse also undergoes inflation and in this case its a universe from "something". So whilst Krauss seems to be right, inflation does make Vielnkins model more plausbile ; its a very incomplete picture. You cant disntinguish Vilenkin model form say LQC bounce by confirming inflation happened.
Im not sure why, but popular accounts of cosmology seem to like inflation, like the brane clash model, but LQC boucne seemes to be ignored by many popularisers. Krauss is guilty of this, but hes far from the only one.
I dont see why Krauss cant promote his religious beliefs, there's plenty of religious people claiming cosmology supports their religious position. Somebody needs to respond to that. Krauss reposnse is not the way I'd respond. I think its better to say we dont know the origin of the unvierse and the religious often imply we do, rather than - hey it might have come from nothing. but perhaps its a better response than silence.
I just noticed this. What do you have in mind for a finite flat universe? Wouldn't it either have to be a manifold with boundary or else be an infinite flat manifold with the mass energy all lying within a bounded region (which would not be consistent with the cosmological principle, not that that's necessarily a show-stopper).
The issue is that this sort of thing tends to be expected when you are talking with a popular audience. People and the press will react to statements in rather predictable ways, so if you spend two hours talking about something and then mention "God" gets what gets quote. We've had a lot of this recently with the "God Particle" non-sense.
The danger is that people will end up with sensationalism burnout if you aren't careful.
Also talking about "something from nothing" also runs into the possibility of oversensationalism.
Which is very common scenario.
The reason why LQC gets ignored is that it's "boring". None of this cool talk about "something from nothing" or "God stuff."
I don't object to Krauss talking about his religious beliefs. I also don't mind if he supports various candidates or plugs diet Cola. What I do find a bad thing is that lots of people seem to have the impression that science supports his religious beliefs rather than being some personal preference.
There are plenty of religious people claiming cosmology supports their religious position. Usually anyone that argues that ends up with rotten science. The fact that I have big issues with religious people using cosmology to support their philosophy is pretty much the same reason I have big issues with atheists do the same thing.
The trouble is that we pretty soon will figure it out. The cool thing about cosmology is that we are making a *lot* of progress in figuring out the origins of the universe. Unknown is not unknowable.
The thing about inflationary models is that a lot of them have the universe being some constantly expanding field, and then a "bubble" drops out of it and stops expanding. That "bubble" forms our entire universe.
There are some big philosophical issues here involving how much you can extrapolate from the data. The good news is that we are ending up with so much data, that it looks like we can figure out a great deal.
One other thing to think about. If we can produce a child universe in the laboratory, then presumably some transdimensional being who is bored can produce one in their laboratory ending up with us.
Having thought about it a bit more, I wonder if the reason LQC bounce scenarios are "boring" is that they are less of an ultimate answer. Why do you think? Suppose we found the universe was eternal say like in the Caroll/Chen model or something like that or suppose we found it did come from nothing. Now that's a lot closer to some ultimate answer than our universe bounced from another one that collapsed, where did that unvierse come from? Answer : no idea.
The latter I personally find v exciting becuase it means there's more to learn. But perhaps others dont and maybe that's the probelm. Although if it turns out there's some comsic censorship and we can never know what happened on the other side of the bounce that will be very unsatsifying. But whilst LQC may be less satisfying it seems more liklely to get into a testable format and lets hope someone should be making more noise about that.
I agreer with most of what you said. When you say you have a problem with atheists doing the same thing. Doesnt it depend what you mean by atheist? There are postive and negative atheists. Positive atheism asserts god does not exist. Negative atheism is the rejection of belief in god usually on the grounds of insufficient evidence. Since the latter is simply the null hypothesis applied to the god question this form of athiesm seems entirley consistent with the scientific endevour. But if you want to coontinue to discuss this issue I imagine theres a different forum area to go forward.
It's also that the LQC approach is "worry about gravity and don't try to come up with a theory of everything."
On the other hand, the quantum fluctuation models tend to posit that the universe "dropped" out of an expanding field.
If someone thinks that God is unnecessary, I don't have a problem with that. I do have a problem with someone calling me "delusional" because I happen to believe in God, which is the position that Richard Dawkins takes, and part of the reason that Krauss has gotten a lot of press is that Dawkins wrote a section of Krauss's book.
It's odd but I have some young earth creationists that I have to apologize to. Way back when when I was arguing with young earth creationists, I found that they really didn't care that much about the age of the universe. The thing that worried them was the idea that scientists had this agenda of "getting rid of God everywhere" and so they were resistant to accepting scientific evidence because "first you get us to accept that the universe is 13.6 years old, then next you get rid of the crosses and Bibles from our houses and tell us that how to raise our kids." Part of getting them to accept scientific evidence, was to assure them that scientists weren't trying to "abolish God."
It turns out that I wasn't, but Dawkins clearly is, and since Krauss has Dawkins write a section in his book, I don't think it is opposed to Dawkin's agenda. I wish Stephen Jay Gould was still around.
Part of this is a US/UK thing. Religion is very strong in the United States, whereas in the UK, I'm told that it's sort of dying out.
A universe with the topology of a 3-torus would have Euclidean geometry, but no boundary.
Essentially, a 2-torus is the familiar surface of a doughnut. This may seem to curved, but it is still Euclidean. Parallel lines stay parallel, the angles of a triangle added up to 180 degrees, etc.
A 3-torus would be the higher dimensional generalization.
Separate names with a comma.