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Physics, Astronomy & Cosmology / Re: Talking about Physics

« on: Yesterday at 09:23:37 »

Philosophy tries to decide which questions are meaningful; Physics just does some experiments.

No. Philosophers assert which questions are meaningful, then question the meaning of meaningful until they disappear through their own anal sphincters. Physics is about discovering and predicting useful and interesting stuff.

As an experimental physicist I'm quite used to the banter of engineers ("bloody scientist...") and theoretical scientists ("oily-fingered engineer...") but nobody has ever insulted me with the title of philosopher!

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Physics, Astronomy & Cosmology / Re: Talking about Physics

« on: Yesterday at 09:14:47 »

What does the existence of energy mean, anyway?

Physics is the business of constructing mathematical models of what happens (or doesn't happen - the branch of physics known as civil engineering). Within those models, energy is a conserved quantity in classical physics, and remains conserved as mass-energy in relativistic physics. Nothing more or less.

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Physics, Astronomy & Cosmology / Re: Are there any philosophical or other implications to the underlying randomness

« on: Yesterday at 09:08:09 »

So the decay of the nucleus is only of significance when it is measured (to my mind) and  this "measurement" is a synonym with "interaction"

A whiff of anthropocentrism here! The decay of a nucleus is of huge consequence to the nucleus itself, which ceases to exist or spawns daughters, even if there is no observer.
A lot of philosophical nonsense derives from the technical term "observer" that we use in science simply to denote a plane in spacetime through which information passes.

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Plant Sciences, Zoology & Evolution / Re: Is religion killing us?

« on: 06/06/2023 16:15:42 »

Civilisation is specialisation. There are hunter-gatherers who don't specialise but live in forests where fruit is easily available and fish or small animals are abundant,so any sharp stick will feed you. In less favorable environments you need more sophisticated weapons, cooking pots, permanent buildings, and so forth, and these are more efficiently produced by specialists so you need to establish trade between the makers and the hunters. Problem is that some people are just bloody useless parasites so they invent reasons why you should continue to feed them as adults, and they become politicians, lawyers, philosophers and priests..

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Physics, Astronomy & Cosmology / Re: why do a lot of people confuse between interference and diffraction?

« on: 06/06/2023 16:04:31 »

Wave propagation in a string depends on whether you waggle one end of a long, soft, heavy rope, so you propagate sine waves along its length, or pluck the middle of a short, stiff, light wire whose ends are fixed, so you can only produce standing waves with nodes at the ends.

Apparently AI doesn't  know what a guitar is, or the difference between pluck and shake. Not that it matters at all, because anyone who wants to play a guitar knows exactly what they mean, and anyone who understands physics can spot bullshit. As usual, the contribution of AI is negative.

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Physics, Astronomy & Cosmology / Re: Talking about Physics

« on: 06/06/2023 07:07:10 »

The meaning is simple: the square of the amplitude of a wavefunction at any point in space is the probability of finding the particle at that point. If you have lots of particles, say valence electrons in a covalent material, the square of their wave function is known as the electron density map (physics) or group orbital (chemistry) , which determines the physical and chemical properties of that material.

The intensity of a beam of particles is the number of particles passing through unit area in unit time. Spatially, it's going to look like a wave function of some sort if you wait long enough.

And once again you are in danger of confusing model with reality. We can predict  an interference pattern by superposing wave functions, but where an individual photon/electron/buckyball goes within that distribution is entirely random. It's no big deal: you can predict the outcome distribution of an infinite number of dice throws or even coin tosses very accurately, but each throw is unpredictable. Nothing is "coded in a superposition" to determine what happens next.

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New Theories / Re: Where does quantization of energy of electromagnetic radiation come from?

« on: 05/06/2023 23:09:16 »

To be honest I'm surprised Alancalverd uses a 1/r2 law as an approximation at any range

It's good enough to persuade clinical folk not to take ferromagnetic objects inside the magnet cage without boring them with divs and curls. I'm sure you could calculate the precise acceleration of a flat-screen television in a 3T field, but my problem was how to extract the debris without scaring the next patient.

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Physics, Astronomy & Cosmology / Re: why do a lot of people confuse between interference and diffraction?

« on: 05/06/2023 22:58:26 »

If you are ever in London, I can highly recommend a visit to Bazalgette's Crossness Pumping Station - amazing Victorian engineering and decorative ironwork and tiles worthy of a cathedral, being restored by brilliant and talented enthusiasts. I took a guided tour last summer beginning with a walk around City public toilets and the history of Cockney poo since the Romans, a lecture on the Great Stink (1858, not the current government) then a boat trip along the Thames to the Station and Museum of Toilets. Marvellous day out!

Interesting that Bazalgette's descendants now produce TV shows like Big Brother - they must have sh1t in their DNA!

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Physics, Astronomy & Cosmology / Re: Talking about Physics

« on: 05/06/2023 22:46:58 »

Not complex. They are both real particles with charge and mass.

In field theories particles have complex probability amplitudes.

But the probability is A² so real particles have real distributions.

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Physics, Astronomy & Cosmology / Re: why do a lot of people confuse between interference and diffraction?

« on: 05/06/2023 17:20:01 »

My daughter-in-law is a civil engineer with an interest in sewage. I'll ask her about the statistics of turds, both raw and polished.

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Physics, Astronomy & Cosmology / Re: Talking about Physics

« on: 05/06/2023 17:16:57 »

it is commonly said that as a student of physics all you will do is study the harmonic oscillator in ever increasing levels of complexity and detail.

Spoken like a mathematician!

Never mind the spherical cow in a vacuum, I once said "physics is a trivial particularisation of mathematics" and then spent 10 years calculating, designing and building just one particularisation of physics, based on a thermal diffusion equation, not a harmonic oscillator!

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Physics, Astronomy & Cosmology / Re: Talking about Physics

« on: 05/06/2023 17:09:03 »

if optical measuring instrumentation  was sufficiently sensitive  might it ,in theory pick up  directly  the interference pattern from one ,two or three dots?

Easier with x-rays, but the answer is yes, we can detect individual photons, and they do indeed arrive at random with the spatial probability distribution as calculated from the continuum-wave analysis.

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Physics, Astronomy & Cosmology / Re: Talking about Physics

« on: 05/06/2023 08:46:49 »

Not complex. They are both real particles with charge and mass.

And beware of "required": it is a technical term in mathematics that constrains our models, but nothing is "required" in physics - it either happens or it doesn't, and if it doesn't, we have to change our model.

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Just Chat! / Re: Is there a universal moral standard?

« on: 04/06/2023 22:59:09 »

Never mind ice cream. Every book for sale at the airport bookshop is a "best seller".

Perhaps they were really best seller for a day, or an hour.

Even assuming anyone would know, surely you have to print the cover before you sell any?

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New Theories / Re: the forgotten aether,2023

« on: 04/06/2023 19:49:25 »

It's not a real video of an actual event. It's a simulation made in a computer:

Heretic!
Nobody is allowed to question computer simulations nowadays.
I recently complained to a local government "consultation" that their new million pound cycle path not only made the road and sidewalk dangerous, but wasn't actually used by cyclists. My complaint was dismissed  because their expensive consultants' computer model said it would be.

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New Theories / Re: Where does quantization of energy of electromagnetic radiation come from?

« on: 04/06/2023 19:39:26 »

Not quite an inverse square law because there is no point source of magnetic field, but Wikipedia sets out all the equations you are likely to need, and when we are dealing with the projectile effect of an MRI magnet on a steel oxygen cylinder, hammer head or nut and bolt, an inverse square law is an adequate approximation from 3 meters distance until the projectile becomes supersonic at about 0.5m from the patient.

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Physics, Astronomy & Cosmology / Re: why do a lot of people confuse between interference and diffraction?

« on: 04/06/2023 16:17:38 »

There's a technique called self reflection, which has been shown to significantly improve answers of AI models.

However much you polish a turd, you end up with a turd.

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Physics, Astronomy & Cosmology / Re: why do a lot of people confuse between interference and diffraction?

« on: 04/06/2023 16:16:44 »

When a guitar string is plucked, it vibrates and produces a wave that travels along the string. This wave is a longitudinal wave, which means that the particles of the string move back and forth in the same direction that the wave is traveling.

Wrong, obviously. Not a good starting point for an essay.

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Plant Sciences, Zoology & Evolution / Re: Is religion killing us?

« on: 04/06/2023 14:32:21 »

Later, all these settlements, which arguably were some of the first temples and the first elite societies, were all buried and not by natural means. It was deliberate.
It's remarkable that Neolithic peoples went to all that effort building them, sustaining the people who chose to live there and not hunt, and then burying them. You have to ask about what the motivation was.

There is no evidence of irrationality or superstition in Neolithic structures. Personal grave goods and food make sense "just in case" the corpse revives, or as an indication to later generations of the previous status of the corpse, or even Norse and Gypsy traditions of burning everything so the next generation thinks forwards rather than backwards,  but the careful alignment of buildings with solar and siderial events points to their importance in long-distance seasonal trade, where calendar synchronisation is essential to success. 

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Physics, Astronomy & Cosmology / Re: Talking about Physics

« on: 03/06/2023 22:19:04 »

Yes and no! There are plenty of examples of diffraction and interference of macroscopic waves. What is remarkable is that whilst individual particles produce random events (clearly quantum phenomena), the spatial distribution of those events is as predicted by a wave model.

Pattern recognition is an odd business.Humans tend to see "hyperuniformity" - imposing patterns on data where none exist, because  we have a preference for geometry. This has some advantages, say in navigating through a remebnered but now modified landscape, because we can ignore a few anomalies, but it can lead to errors in making very confident predictions that turn out to be completely wrong. Simple example: I say 1,3,5... and you say 7,9.... Wrong! I was enumerating primes, so the amswer is 7,11... and whilst it can be proved that there is no pattern to the occurrence of prime numbers, they do tend to occur in sort-of-periodic clumps!