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Physics, Astronomy & Cosmology / Re: Why is light bent whent it passes a massive body in the space?

« on: 12/02/2021 10:29:24 »

Should the question be 'why does a massive body bend spacetime'?

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Physics, Astronomy & Cosmology / Re: What do you call the coloured light that comes out of stained glass?

« on: 19/01/2021 10:41:40 »

How has this topic got nearly 28,000 views?

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Physics, Astronomy & Cosmology / Re: Is there a simple explanation of Bell's experiment?

« on: 26/12/2020 09:49:39 »

It's only 'good and very clear' because you understand it. I posit that it is not 'good and very clear' for the majority of the target audience.

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Physics, Astronomy & Cosmology / Re: Is there a simple explanation of Bell's experiment?

« on: 24/12/2020 08:17:03 »

It's a polite way of saying Philip Ball doesn't understand it.

Phillip Ball did understand it and proceeded to offer his own explanation which I thought joined the category of 'not at all easy to follow'.

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Physics, Astronomy & Cosmology / Re: Is there a simple explanation of Bell's experiment?

« on: 23/12/2020 11:04:53 »

The lecture can be viewed on YouTube by searching:-
Phillip Ball Understanding Quantum Entanglement

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Physics, Astronomy & Cosmology / Is there a simple explanation of Bell's experiment?

« on: 21/12/2020 10:45:50 »

Philip Ball, the science writer, whilst giving a lecture at the RI on entanglement said: "Personally, I have never seen an explanation of John Bell's experiment that is at all easy to follow".

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Physics, Astronomy & Cosmology / Re: How does light move in a vacuum?

« on: 02/12/2020 12:23:31 »

The complexity of the mathematics overwhelmed me especially when I found permittivity being defined in terms of 'c'.

Could you offer a simplified derivation of 300,000 km/s for 'c'?

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Physics, Astronomy & Cosmology / Re: How does light move in a vacuum?

« on: 01/12/2020 19:28:20 »

If everything is "relative", why does light have a fixed speed of 300,000  kms per second. Why that particular value, and not say, 500,000 kms per second?  Or any other value?  Such as 0, or infinite?

Both charles1948 and I in the past have asked this and a complete answer has not been given.
Why 300,000 km/s and not another value?
Can an explanation be given that derives the 300,000 km/s?

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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