Humbled by Hubble

[Roosters for ever]

I think that's a fudge, personally. Quantum foam isn't "nothing". A quantum field isn't "nothing", even if its value happens to be zero everywhere at some particular time.

I recall it went something like this....
We once saw and defined nothing as "empty space" ....it certainly looks like nothing! and then it was shown that this empty space that we saw as nothing, was seething with virtual particles popping in and out of existence...or the "Casimir Effect"
He then goes on to define "nothing" as an unstable physical state or the quantum vacuum. He argues this "nothing" as a bubbling, dynamic field of virtual particles popping in and out of existence, capable of spontaneously creating "something" (matter and energy) through quantum fluctuations. A Universe from nothing in effect.
I havn't the book at this time, as I lent it out a while back and have not yet got it back.

If he wants to say that the universe came from a bunch of quantum fields, that still leaves open the question of where the quantum fields came from.

He speculates that these quantum fields defined as nothing, are what has existed for eternity basically.
Personally I find that far easier to accept than some magical supernatural creator.

(I must admit, I lost a lot of respect for Krauss after the details of various incidents in his personal life came to light. Turns out he also spent time hobnobbing with Jeffrey Epstein, and he's in the Epstein files - including where he asked Epstein for advice on how to handle negative publicity surrounding allegations of sexual harassment.

Not that any of this impacts whether he knows his physics or not, but it does mean that I'm not going to be giving him any money by buying his books, going forward.)

I had not heard of that and would have felt likewise. I bought his book long before I ever heard of Epstein.

 

[Roosters for ever]

Yes, it has always seemed to me that the hypothesis of the universe expanding from fluctuations in fields with a net value of zero is chiefly of interest in that it implicitly denies the concept of an original singularity, which is one of the other hypotheses. It is after all meaningless to speak of a "field" unless it has some spatial extent. Also it implies there was no start to time, i.e. no t=0 moment, as there is in the singularity hypothesis.

But neither of these conjectures is really science, as there is no way to make any observation to discriminate between these ideas.

A singularity, both from whence the big bang arose and what we have at the center of black holes, are where our laws of physics and General relativity break down. So it really doesn't deny the singularity concept. He "speculates" on what is happening at the singularity/quantum/Planck realm of space and time in some as yet unknown state, this unknown state being the quantum foam.
The start to time t=0 is the same as the start to space, "AS WE KNOW THEM" possibly speculatively from an epoch where we don't know them. (Or the quantum foam)
Yes it is speculation or if you like, conjecture, but Krauss doesn't hide from that position.

 

[Roosters for ever]

Yes, it has always seemed to me that the hypothesis of the universe expanding from fluctuations in fields with a net value of zero is chiefly of interest in that it implicitly denies the concept of an original singularity, which is one of the other hypotheses. It is after all meaningless to speak of a "field" unless it has some spatial extent. Also it implies there was no start to time, i.e. no t=0 moment, as there is in the singularity hypothesis.

But neither of these conjectures is really science, as there is no way to make any observation to discriminate between these ideas.

beil:

The big bang was the beginning of space as we know it. Space came into existence at the big bang and it has been expanding ever since. That's the theory.

 

[beil]

I am interested to know what your experience of World War II was like. Would you like to share a bit more about yourself? I don't get to talk to many 95 year olds. You must have a lot of experience worth sharing that would have to be more interesting that your pseudo-physics.

Once bombing became menacing, we kids were evacuated, like our equals in London. First trip to Chechislovakia in 1941, top secret/hidden because of impending invasion of Russia. Another 6 month in Austria, then on the Baltic seaside. Often saw hundrets of B17s, escort fighters. planes falling out of the sky. Music teacher secretly playing us Jewish composers. After Stalingrad prayer in church. ha ha. Lucky to be in the last pocket in May 1945. because !4 year olds in Berlin, Aachen were drafted into the auxiliary, -armed with bazookas, often executed when captured. thought to be Nazi fanatics, -- really boy scouts with German flavor. Left for North America to escape the constant turmoil in Europe.