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Physics, Astronomy & Cosmology / Re: Could gravity be like temperature and not be able to be quantised?

« on: 01/10/2020 18:56:42 »

"Could gravity be like temperature and not be able to be quantised"?

This is a rhetorical question I heard Freeman Dyson ask and at the same time he made the point that General Relativity and Quantum Mechanics should not be unified

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Physics, Astronomy & Cosmology / Could gravity be like temperature and not be able to be quantised?

« on: 03/09/2020 13:00:30 »

So much work into unifying general relativity and quantum mechanics but could the effort have been made elsewhere?

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Physics, Astronomy & Cosmology / I rate 'many worlds' people together with flat-earthers. Am I wrong?

« on: 06/08/2020 20:09:34 »

Both possess beliefs that I find unconvincing.
The former harder to prove erroneous than the latter.

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Physics, Astronomy & Cosmology / Re: An expanding flat universe?

« on: 12/06/2020 10:17:17 »

How does string theory describe the shape of the universe?

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Physics, Astronomy & Cosmology / Re: An expanding flat universe?

« on: 11/06/2020 21:15:21 »

What will be the ratio of its thickness to its length?

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Physics, Astronomy & Cosmology / Re: Has physics made any meaningful progress in the last 40 years?

« on: 06/06/2020 10:07:58 »

I would imagine that Hossenfelder would counter that Higgs made his prediction over half a century ago.

She makes the point that we are still trying to solve the same problems that we were decades ago. Breakthroughs are wanted in the foundations of physics.

With regards to Dark Matter - Her words, "The truth is, we're still not sure that it actually exists".

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Physics, Astronomy & Cosmology / Has physics made any meaningful progress in the last 40 years?

« on: 05/06/2020 18:47:19 »

Sabine Hossenfelder asked this when she launched her book 'Lost in Math'.

She cited the LHC not discovering new fundamental particles and physicists relying on unscientific methods to develop new theories. She criticised how they became obsessed with 'beauty' in their equations.
 
She said they should concentrate on resolving inconsistencies in existing theories citing the missing quantization of gravity, the measurement problem and aspects of dark matter/energy.

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Physics, Astronomy & Cosmology / Re: Is the speed of light constant?

« on: 29/05/2020 20:59:21 »

The link gave the following - "Maxwell combined displacement current with some of the other equations of electromagnetism and he obtained a wave equation with a speed equal to the speed of light".

It is a criticism of Wiki that it tends to explain concepts to people who already understand them. Typically not defining the constituents of the formulae.

The derivation of the speed of light was not clear to me.

Is there a simpler explanation?

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Physics, Astronomy & Cosmology / Re: Is the speed of light constant?

« on: 29/05/2020 18:07:21 »

Light travels about 186,000 miles/sec. in a vacuum. Why this speed, and not some other speed?

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Physics, Astronomy & Cosmology / Re: Do electromagnetic waves have a fixed speed?

« on: 23/05/2020 09:40:59 »

Deriving the speed of light from Maxwell's equations is similar to Bell's inequality in that both are universally accepted but I have never seen an easy to understand explanation for either.

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Physics, Astronomy & Cosmology / Re: Why do some burnt matches float and others sink?

« on: 26/02/2020 18:09:55 »

Not answering the question but on delving into this I have found that a burnt match is attracted to a magnet!

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Physics, Astronomy & Cosmology / Re: Was the Big Bang the beginning of the universe?

« on: 15/11/2019 10:15:12 »

Here's the answer --
https://www.quora.com/What-banged-at-The-Big-Bang

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Physics, Astronomy & Cosmology / Re: What happens when both slits are observed by in the double slit experiment?

« on: 05/11/2019 09:48:14 »

You have hit at the heart of quantum mechanics, after a century there are still many interpretations.
Sean Carroll narrowed it down to really only three contenders --
1. Many worlds.
2. Hidden variables.
3. Collapse theories.

In the future it will be said: "they had quantum mechanics fall into their lap, they used it but did not understand it".

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Physics, Astronomy & Cosmology / Re: Was the Big Bang the beginning of the universe?

« on: 15/10/2019 14:01:19 »

Relevant to this thread?

"Truth is ever to be found in simplicity, and not in the multiplicity and confusion of things".
-- Sir Isaac Newton

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Physics, Astronomy & Cosmology / Re: What is the cosmic microwave background?

« on: 08/10/2019 19:30:10 »

It is easy to understand that the sun has already gone down 8 minutes before one sees it set but I can understand the difficulty in visualising the formation of the CMB.

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Physics, Astronomy & Cosmology / Re: Was the Big Bang the beginning of the universe?

« on: 15/09/2019 18:40:29 »

Sidney Morgenbesser, his professor at Columbia, said to Jim Holt "even if there was nothing you still would not be satisfied".

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Physics, Astronomy & Cosmology / Re: Was the Big Bang the beginning of the universe?

« on: 12/09/2019 09:12:31 »

I recollect the words of John Wheeler, he concluded:

Can we ever expect to understand existence?
Clues we have and work to do, to make headway on that issue.

Surely someday, we will grasp the central idea of it all as so simple, so beautiful, so compelling that we will all say to each other, “Oh, how could it have been otherwise! How could we all have been so blind so long”!

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Physics, Astronomy & Cosmology / Re: Was the Big Bang the beginning of the universe?

« on: 17/08/2019 08:43:39 »

Sean Carroll believes the universe is infinite in both directions i.e. it never had a beginning, it was always there and it will never end.

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Physics, Astronomy & Cosmology / Re: What are the implications of a change in the Hubble constant?

« on: 10/08/2019 10:39:38 »

Is that all?

The news item I read was headlined -- New measurements could upend the standard theory of the cosmos that has reigned since the discovery of dark energy 21 years ago.

But it did not say how.

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Physics, Astronomy & Cosmology / What are the implications of a change in the Hubble constant?

« on: 09/08/2019 19:26:28 »

I am asking this after Wendy Freedman and Adam Riess recently made their case for different expansion rates of the universe.