Yep

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Musicplayer..No matter what thread you enter, you ruin it!

Music player is in her own universe. All I know is that I can only rarely read an entire post by her.

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Bob DeWoody

My motto: Never do today what you can put off until tomorrow as it may not be required. This no longer applies in light of current events.

At a recent meeting in Japan of string theory experts (String2018) it was said that multiverses are much less than the 10500 allowed by the theory, since many of them are impossible. None of the particles associated with them has been found by experiments,so far.
Tullio

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I had to do some research on the net to understand the number 10500.
Actually in string theory it's 10^500 of possible ‘worlds’ with different self-consistent sets of laws and constants.
That's a very very huge number. As a comparison there is about 10^80 atoms in our universe.
So now it less then 10^500. Almost was about to say "Thank God":)
Did they said what the number is now?

Strings 2018 talks are on the net.
Here is one of them https://www.youtube.com/watch?v=fU8sJRCRz24

I got the number from Le Scienze, Italian edition of Scientific American. Maybe they got it wrong and it was actually 10 exp 500. No, I don't have a new number, but I think this is all a fancy show. The LHC, which has sent me a polo shirt to thank for my contribution, has not found any particle foreseen by springs theory.
Tullio
No, Le Scienze was right,it was me that got it wrong. Maybe I was thinking of the Lord having to create a number of universes.10500 was a heavy enough load , 10 exp 500 is not possible at all.

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...10 exp 500 is not possible at all.

Well it's a finite number so it's possible.
However infinity is not.
Scientists view on the concept of infinity.
https://www.dailymotion.com/video/x20grta
The problem with Einstein's laws on gravity is that the calculation include a division by a radius.
Radius smaller than a Planck length doesn't give a reasonable answer.
A radius of 0 gives you an infinite gravity which is of course absurd.
I guess that's because in our universe everything comes in quantas.
Even space and time.
You cannot split those sizes a infinite times like you can do in math.

Infinitesimals need to be given more credence in Math and of course Physics.

These are numbers smaller than any real number but larger than zero--seems to relate to Planc-like thinking.
Like I have posted before: Throwing away (dx)(dy) in our Calculus may just be admitting our uncertainty about the very very small part of our world.

Too bad that Einstein couldn't weigh in on the topic from beyond the grave:

Physicists have learned to treat infinities in quantum electrodynamics by a method called renormalization.
Tullio

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Physicists have learned to treat infinities in quantum electrodynamics by a method called renormalization.
Tullio

Yes.
A Feynman diagram illustrating that
Renormalization was first developed in quantum electrodynamics (QED) to make sense of infinite integrals in perturbation theory.

Oh dear. Now I'm getting a headache...
Perhaps a pint of beer will help.
Ahh. Quantum foam:) That's better. I can see clearly now.
Quantum foam (or spacetime foam) is the fluctuation of spacetime on very small scales due to quantum mechanics. The idea was devised by John Wheeler in 1955.

Is the string theory dead?
A controversial new paper argues that universes with dark energy profiles like ours do not exist in the “landscape” of universes allowed by string theory.
https://d2r55xnwy6nx47.cloudfront.net/uploads/2018/08/dark-energy-may-be-incompatible-with-string-theory-20180809.pdf

The paper, by the prominent string theorist Cumrun Vafa of Harvard University and collaborators,conjectured a simple formula dictating which kinds of universes are allowed to exist and which are forbidden, according to string theory. The leading candidate for a “theory of everything” weaving the force of gravity together with quantum physics, string theory defines all matter and forces as vibrations of tiny strands of energy. The theory permits some 10^500 different solutions: a vast, varied “landscape” of possible universes. String theorists like Wrase and Vafa have strived for years to place our particular universe somewhere in this landscape of possibilities.
But now, Vafa and his colleagues were conjecturing that in the string landscape, universes like ours — or what ours is thought to be like — don’t exist. If the conjecture is correct, Wrase and other string theorists immediately realized, the cosmos must either be profoundly different than previously supposed or string theory must be wrong.

Maybe they should read Isaac Newton. "Hypotheses non fingo".
Tullio

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I read that most of the mathematics needed for string theory is not even yet developed.
So how can you draw any conclusion at all from string theory?

Btw. Newton didn't have the mathematics needed as well when he made The Law of Gravity.
So he invented Calculus to make it work.

String theory is a convenient fiction such as is the electron to help us in an attempt to understand and explain the world as we perceive it.
I remember a lecture in string theory at Bell Labs in Holmdel New Jersey at which the presenter predicted a GUT emerging from the work in a few short months. That was 30 + years ago. I cannot recall the presenter's name . He was on loan to Princeton from Queen Mary College as I recall. I think that it was Michael Green.

I don't know why string theory was thought to be the holy grail in this regard. Did it explain the apparent masses of the known particles or explain super symmetry ?

We have here something very much akin to religion with our high priests, unbelievable assertions, mathematical sleights of hand and unproven conjectures and parables.
My Alter Ego feels that he is entitled to weigh in on these ideas as well.

String theory hypothesizes a number of particles. None was found. Dark matter should consist of weakly interacting massive particles.None was found. We are flying blind.
Tullio

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I've been watching Stephen Hawking's Universe on the Curiosity channel and the more I watch the less I understand what I am seeing. One segment was about a physicist who is trying to build a perfect computer model of the universe from a time shortly after the big bang to the present. I have a strong feeling that is as impossible as it was for the ancient greeks.

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Bob DeWoody

My motto: Never do today what you can put off until tomorrow as it may not be required. This no longer applies in light of current events.

String theory hypothesizes a number of particles. None was found. Dark matter should consist of weakly interacting massive particles.None was found. We are flying blind.
Tullio

i think what you said is important. nothing of those lucrubations has been found so all of these are non sense.
thats my opinion

+1

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Bob DeWoody

My motto: Never do today what you can put off until tomorrow as it may not be required. This no longer applies in light of current events.

When you fired atomic-scale entities, such as a single electron, towards a double slit, you can imagine there are gravity forces between this single electron with every atomic-scale entities on the screen.
And it is the gravity forces between this single moving electron with every atomic-scale entities on the screen that produce the interference pattern.
That is why even a single electron will produce an interference pattern on the screen.

(Imagine the yellow dashed lines are the gravity forces between this single electron with every atomic-scale entities on the screen.)

Gravity forces from the screen? If so, why would the width of the interference pattern become wider if the screen is moved further away?
No. It's the electron that behave like a wave. Which is very strange because the electron have to pass both split at the same time to create two waves that interfere with each other after the split. But obviously it does...

On the November issue of CERN Courier there is an interview with Gabriele Veneziano, une of the fathers of strings theory. Read it, it is very interesting.
Tullio

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