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#51436 03/27/14 03:04 PM
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Really interesting discussion between Lubos and Matt Strassler and I for once I actually side with with Matt for reasons I have expressed in other discussions on this very subject.

Matts two articles:
http://profmattstrassler.com/2014/03/21/did-the-universe-begin-with-a-singularity/
http://profmattstrassler.com/2014/03/26/which-parts-of-the-big-bang-theory-are-reliable/

Lubos response article:
http://motls.blogspot.com.au/2014/03/the-universe-really-began-with-big-bang.html#more

I guess that means I am doing a disservice to science a claim Lubos levels at Matt smile

Quote:
I think that in general, Matt is doing a disservice to science and the laymen's understanding of science by these constant "doubts about all important insights that are not covered by any appropriately strong points or evidence".

Last edited by Orac; 03/27/14 03:05 PM.

I believe in "Evil, Bad, Ungodly fantasy science and maths", so I am undoubtedly wrong to you.
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I went and took a look at Lubos' article. I agree with you that he is wrong in at least this case. Having read through it I think that his big problem is that he (Lubos) is a very strong supporter of String Theory. He feels that ST is the complete answer to all the problems of physics. Of course this has not been established, and Matt Strassler is aware of that fact. I noticed also that Lubos kept trashing Loop Quantum Theory, which has also not been either validated or invalidated. Basically he is so locked into ST that he can't stand for anybody to cast any doubts on it.

I suppose I should add Lubos to my list of places to check regularly, but I sometimes have trouble reading his site. For one thing he sometimes gets too technical and is hard to follow. For another he is extremely wordy, all his articles are a lot longer than I think they need to be. And for one more thing his site is just flat hard to read. Those small characters on the dark green background are kind of hard for me to read.

Bill Gill


C is not the speed of light in a vacuum.
C is the universal speed limit.
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I haven't read all of Motl's post yet, but I am encouraged by the apparent lack of maths! Perhaps I shall be able to understand this one. smile

Personally, I think Matt's frequent calls for caution, rather than just accepting everything on sight, are wise and refreshing.


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I would agree with both of your comments totally.

Originally Posted By: bill
I suppose I should add Lubos to my list of places to check regularly, but I sometimes have trouble reading his site. For one thing he sometimes gets too technical and is hard to follow. For another he is extremely wordy, all his articles are a lot longer than I think they need to be. And for one more thing his site is just flat hard to read. Those small characters on the dark green background are kind of hard for me to read.


The target audience is not Layman he has clearly stated that a number of times it is aimed much more at a physics graduate level. I agree with your comments on the blog but unlike someone like Ethan the blog is not really a commercial thing from my understanding, so I cut it some slack. (PS Can someone tell me if this sentence finally reads right...I hate english)

He is most definitely aggressive and opinionated in most posts but at the end of the day he is there to discuss science not win a popularity contest. Contrary to what he thinks he appears to think he is not always right but I am not telling him that for the spray I would get smile

Sascha Vongehr once described him as "a high functioning idiot savant whose considerable abilities in juggling mathematics and its application" but "a social misfit" and went on to say "He could be a leading physicist, yet he ends up being a loudmouth destroying straw-men". That is pretty close to how I view him but in science history there are many such characters you don't have to look far Feynman and Tesla spring immediately to mindsmile

Originally Posted By: Bill S
Personally, I think Matt's frequent calls for caution, rather than just accepting everything on sight, are wise and refreshing.


That is unlike you there is an infinity on the line here and you objected when I used almost the same argument smile

Last edited by Orac; 03/28/14 01:26 AM.

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Quote:
That is unlike you there is an infinity on the line here and you objected when I used almost the same argument


Good point, but I'm not in an exchange of views with Matt. smile

One has to defend one's corner!


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I've been plodding through Lubos Motl's post at odd moments.
So far, a few questions and comments come to mind:

But the main point is that the Big Bang theory is correct and among other things, it implies that the conditions had to be basically infinitely extreme at the beginning.

What does he mean by “the beginning”. To extrapolate back to a point where anything was infinite would take infinite time. How can a beginning be identified?

When Matt suggests that there was no singularity and that the Big Bang could have been non-existent, his claims are not quite sharply defined. Whether you consider them true or false, defensible or indefensible, depends on the definition of the "Big Bang", the definition of the "singularity", the degree of certainty and the kinds of confirmations (empirical, direct, indirect) that you require to say that you "know something", and on the choice of the mathematical formalism that is connected with the notoriously vague words used in the human language.

While it is possible to choose from various definitions of “Big Bang” or “singularity”; how is it possible to be sharply defined if one is talking about broad concepts, such as the idea of the Big Bang, or the idea of a singularity?

Now, the status of the claim that "there was the Big Bang" is completely analogous. Like other claims in science, this sentence doesn't include the bold and unrealistic proposition that we have understood everything (or the claim that everything in Nature looks and has always looked like the Big Bang). Instead, the words in this sentence (especially the "big bang") are supposed to describe some objects or events that exist within some incomplete, effective theories that are only meant to approximately describe a limited class of observations and phenomena. And the validity of such insights may be scientifically established independently of the fact that more esoteric processes will be observed and theories that can deal with these more esoteric processes will keep on evolving.

Isn’t this much the same as what Matt is saying; except that Matt says it in a less pompous way that is likely to be more easily understood by the lay audience for whom he is writing?

Yes and No. Some people take the analogy (or identity) of the Big Bang with an explosion too literally and derive many incorrect conclusions out of it. Their excessively explosion-like way visualization of the Big Bang leads them to some wrong ideas.”

This must strengthen Matt’s argument in favour of caution. Presumably, by “Some people”, Lubos means some scientists. If he meant lay people, there would be no real cause for concern, and little point in making the assertion.

As you can see, I do believe that the fight against "the Big Bang as an explosion" is being overfought. Up to a certain "threshold" in the space of questions, it's just OK – not just for the laymen, but for the professionals – to imagine that the Big Bang expansion is an example of an explosion.”

Personally, I think a large part of the importance placed on arguing that the Big Bang was not an explosion is based on the need to stress that the “outward” movement of the Universe is not movement into anything. The usual lay person’s mental picture of an explosion is that it occurs at a point in space, and that fragments are flung outward through space.

We don't mean that the singularity has experienced "exactly infinite" temperatures and curvatures and we surely don't mean that such a singularity had to imply that the laws of physics are internally inconsistent.”

What Lubos seems to be saying here is that there was a singularity, as long as we define it as something other than a singularity!

But there simply is something that is described as a singularity by classical general relativity

Have I missed something here? GR might predict a singularity, but how can it describe one if the equations of GR break down at that point?


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Originally Posted By: Bill S
What Lubos seems to be saying here is that there was a singularity, as long as we define it as something other than a singularity!

“But there simply is something that is described as a singularity by classical general relativity”

Have I missed something here? GR might predict a singularity, but how can it describe one if the equations of GR break down at that point?


What I interpret he is saying is string theory has 10 dimensions and just because it goes to infinity on 4 of the dimensions (3D + time) which we define as a GR singularity under string theory that isn't really a singularity and that is what he means by the laws of physics could still be internally consistent.

So I interpret he is trying to say a GR singularity is not inconsistent because it is not a string theory singularity.

Lubos answered pretty well directly that here (read response 3)
http://physics.stackexchange.com/questions/5270/black-hole-singularity-and-string-theory

So his answer is prefaced around the idea you accept string theory which because it his blog is self evident he does.

Without that fact you are exactly correct Bill S and I agree Lubos argument is very circular.


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With "fairytale physics" anything goes. smile


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