41

Technology / Re: How were images transferred before the digital age?

« on: 08/01/2023 18:31:53 »

Ahh video, hours and hours of people recording their holidays on camcorders,

Before Facebook, you had to photograph your lunch, rush to the chemist, get the film developed, make 25 postcard prints,then go to the post office and send them to your friends, by which time the meal was cold.
But whilst Evan can't see his recent photos on  his new computer, I still have black and white prints of equipment I built nearly 60 years ago, and if you want a good picture of an extinct bison there are plenty of 40,000 year old cave paintings that show you how to hunt them with spears.

42

New Theories / Re: If there was one Big Bang event, why not multiple big bangs?

« on: 04/01/2023 22:58:25 »

When the survival of the fittest is achieved, the conditions for the on-going evolution of higher intelligence are in place

The fittest seem to be viruses, capable of extremely rapid evolution and population growth compared with their hosts. Not sure how you define intelligence, but I think the average virus has an immeasurably low IQ.

43

Physics, Astronomy & Cosmology / Re: Why do my Christmas lights give such a nice ambience?

« on: 04/01/2023 16:28:42 »

Cataract rarely mists the entire lens at once - it tends to form in small nuclei which spread out with time. If all the n nuclei have radius r and the lens aperture is R, then the proportion of light not passing through the cataract is
(R²-nr²)/R²
 which clearly increases rapidly with R for any fixed value of r. I first made this diagnosis when a friend remarked that she couldn't read the signs in a brightly-lit supermarket but had no problem driving at night, and an optician confirmed it a few days layer.

Image "sharpness" increases with decreasing aperture either because the lens is distorted or because you define sharpness as depth of focus. An animal eye, unlike a camera, doesn't really rely on d.o.f. but tends to focus sharply on the object of interest*, so only the first condition applies: the infinitesimal segment of any convex surface approximates to spherical!


*serious problem for sailors and aviators! Thanks to lots of evolution the relaxed "normal" human eye doesn't focus at infinity but at around 20m - where you might find a natural predator or prey that you can do something about. Not a lot of use if you are trying to spot a hostile or converging aircraft in the "blue bowl".

   

 

44

Physiology & Medicine / Re: Quantum Manifestation Code Review

« on: 30/12/2022 14:23:04 »

And the quantum bit?

45

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

« on: 30/12/2022 00:21:48 »

I spent several happy years making and interpreting x-ray diffraction photographs, every one of which literally had a hole in the middle to let the primary beam out. If we didn't do that, the scattered radiation from the majority of the x-rays that passed straight through the sample would fog the film and make the diffraction spots difficult to find. Hence an abiding interest in knowing the difference.

46

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

« on: 27/12/2022 09:51:59 »

At some point in the thread you might have told us why you feel the terms need to be kept so separate but I can't find that on scanning through the thread.  Perhaps you could tell us again.

Diffraction occurs at an edge or a point and results in a downstream wavefront with the same wavelength as the original source, appearing to originate from that edge/point.

Interference is the result of superposition of two or more wavefronts producing maxima and minima with a spatial distribution related to the distribution of the sources. 

If you stand in the shadow of a mountain you may hear the radio signal of a station that is just out of your line of sight. The signal strength you receive decreases smoothly as you move away from the station or further "behind" the mountain. Diffraction. This can cause serious radio navigation errors.

If you have two stations transmitting  the same signal, the intensity you receive will vary sinusoidally as you move in any direction  relative to them. Interference. This was used for very precise long range radio navigation systems such as "Knickebeine" and "LORAN".

47

General Science / Re: How good would a diameter of 111 Km be for a cylinder of diamond 111 Km high?

« on: 23/12/2022 10:04:33 »

Assuming the OP is talking about a space tower, you wouldn't start with a circular cylinder. A cone or pyramid would be far more sensible.

We know the density of diamond (about 3.5 tonnes per m³) and compressive strength (20 GPa) so it is left to the questioner to calculate the minimum diameter of the base of a frustrated cone that will support, say, a 1 m platform at 111 km altitude, assuming the stress at every level is equally distributed at the level immediately below.

   

48

Physics, Astronomy & Cosmology / Re: Is there an experiment that shows the oscillation in the E field of light?

« on: 21/12/2022 10:38:04 »

There is an underlying misunderstanding here.

The wavelength of visible light is orders of magnitude larger than an atom or molecule. When you walk on sand your speed depends on its bulk properties (wet, dry, compacted...) not the interaction of your foot with each individual grain, though the inter-grain mechanics (sharp, soft....) actually determine the bulk property. 

The fact that for instance μ_iron is sometimes enormously greater than most other materials is clearly a function of group (domain) behavior rather than that of a single atom.

As the wavelength of EMR approaches atomic dimensions so we need to model the interaction by quantum rather than wave mechanics, as I stated several posts ago.   At the other end of the scale we can measure μ and ε statically for any substance, and as we can see with the dispersion of white light in glass, these parameters vary with wavelength and with the nature of the transmitting medium, since bulk properties ultimately depend on atomic properties. 

So to address HY's problem: Maxwell's equations describe wave propagation. The wave model works well when considering propagation at wavelengths greater than an atom or molecule diameter and also describes diffraction from a crystal lattice (a bulk property), but does not describe the interaction of EMR with individual atoms, for which we have a particle model. 

Maxwell's equations don't "break down" any more than a train timetable "breaks down" when you want to catch a bus - they predict only and exactly what they say they predict.

49

New Theories / Re: An essay in futility, too long to read :)

« on: 17/12/2022 09:45:11 »

As for if funding ones enemies neighbor with weapons and cash is about defending?

I have no enemies, but I'm always ready to support an innocent potential victim against a stated threat from his enemies.

50

New Theories / Re: An essay in futility, too long to read :)

« on: 15/12/2022 16:39:13 »

How come Canada, Australia & Japan are Not already part of NATO?

Canada was a founding member and is still a member.The others do not have any geographical connection with the North Atlantic.
But don't let the facts spoil a good argument.

51

General Science / Re: Is science a religion.........well if not why is it defended as though it were

« on: 15/12/2022 09:15:18 »

It isn't.

AFAIK nobody has ever started a war or tortured anyone to death in defence of  F = Ma.

A few guys were excommunicated or even burned at the stake for suggesting such heresy, but that is the fault of religion, not science.

52

General Science / Advent calendar maths question!

« on: 14/12/2022 23:21:07 »

This might amuse those of a mathematical persuasion.

We have a novelty advent calendar. For anyone brought up in a different faith, it counts down the days from 1 to 25 December. Ours consists of two numbered wooden cubes which you can rearrange to display every integer from 25  to zero.

What numbers are painted on each cube? 

53

New Theories / Re: An essay in futility, too long to read :)

« on: 12/12/2022 18:28:21 »

A spoonful?

That would be quite enough, if the output is continuous, to justify the entire program.

54

Just Chat! / Re: was the Manahan project a faliure

« on: 11/12/2022 23:38:02 »

Once the western front was established in Normandy, the overland invasion of Germany was an inevitable progression into territory that had been pretty much bombed and strafed into impotence. It still took a year to complete.

Japan was a very different proposition: it was a long way from the major ground forces building in India and the USA and at the range limit of most bombers, never mind land-based fighters. Its infrastructure had hardly been damaged by a few very costly bombing raids. It still had a functioning defensive navy, and the capability of building enough fighters to reprise the Battle of Britain in the air.

The  planned invasion of Japan involved an estimated 300 - 500,000 fatalities and maybe 10 times as many permanently disabled casualties over 2 -4 years, at a far greater cash cost to the Allied economies.

In terms of bang per buck, no ship, conventional bomber or tank comes within three orders of magnitude to a nuke, never mind the "disposable asset" infantry and unavailable air support you need to actually occupy the territory.

Manhattan was worth every penny to my dad training ground forces in the Far East and The Boss's dad dropping iron bombs on a very resilient enemy dug into the Pacific islands.

55

New Theories / Re: An essay in futility, too long to read :)

« on: 11/12/2022 23:09:29 »

Riots, wars, mass migrations, and starvation.  Imagine the ice age, but
in reverse (everyone migrating away from the equator)
with a thousand times the number of migrants
with trucks, buses and guns
and a very good idea of where they are going and why
and a much greater urgency (the planet heats much faster than it cools).

56

Just Chat! / Re: Why is Elon Musk's purchase of Twitter making people so angry?

« on: 11/12/2022 15:09:11 »

The real question is why they opened their accounts in the first place.

57

New Theories / Re: Does science assume aether

« on: 11/12/2022 00:02:26 »

Aether was a fairly logical guess when radio transmission was discovered.  We knew that information can be transmitted by waves in solids, liquids and gases, and now we had the means of measuring wavelength, frequency and velocity of something rather more tractable than light, so the first guess would be that it was carried by some other medium.

Early radio textbooks used "compression of the aether" to explain radio propagation to soldiers, sailors and aviators who needed a quick and practical understanding of phenomena such as frequency, wavelength, diffraction, reflection, dispersion, interference and attenuation that could be visualised with ripples on water and which profoundly affected their life-critical use of the medium.

Maxwell actually derived his propagation equations as theoretical models of "fluctuations in a medium" with properties of permittivity ε and permeability μ. The power of this approach is in allowing us to model and predict propagation in any medium, but the observation that EM radiation propagates through a vacuum at a finite speed independent of direction requires us to assign values to ε₀ and μ₀ analogous to those of a real medium.

The problem with "fluctuations of the aether" is  the calculated elastic modulus and density of the material - the properties that determine the speed of waves. It has to be orders of magnitude stiffer than any known material and orders of magnitude less dense. We have no concept of a less dense material than hydrogen, or a stiffer material than, say, carbon steel. This is the point at which the search for aether becomes somewhat problematic as it also must have zero viscosity  (or the planets would spiral into the sun) and its mechanical properties must be independent of the amplitude and frequency of the wave over at least a range of 10¹⁸ - a degree of linearity unmatched by any other medium.

Therefore the minimum assumption is that Maxwell's model holds true in the absence of any medium, as long as we can assign independent experimental values to ε₀ and μ₀. It turns out that the values we measure from electrostatic and magnetostatic experiments (no need for any compressible medium as nothing is moving) give us the observed value for c.

Thus no requirement for an aether.

58

New Theories / Re: An essay in futility, too long to read :)

« on: 07/12/2022 11:43:27 »

Hopefully not entirely serious though?

Absolutely serious. We should not be arselickers to scum in the Middle East, Russia, or Texas.

59

Physics, Astronomy & Cosmology / Re: Can we detect coloured objects wavelength's by device?

« on: 06/12/2022 21:17:30 »

And when you aim your camera at a blue source you are then sending a carrier at maybe ~0.05m MODULATED with your 450nm signal-you are not sending a carrier at 450nm.

Except that the carrier isn't modulated with a 450 nm signal either, but a digital code for "blue".

60

New Theories / Re: An essay in futility, too long to read :)

« on: 06/12/2022 14:34:38 »

Good to see another enthusiast advocating something. Pity you haven't spelled out the effect of your policy, never mind how you would enforce it.

Third world countries have been getting on pretty well without modern technology or fossil fuels since the stone age, so if anything the technology transfer will have to be in the other direction. Uncomfortable, but sustainable.

Interesting TV program last night (BBC4, Horizon - the lost tribes of humanity - a repeat, available on BBC iplayer) explained how at least four distinct human species disappeared during the last ice age. Survival is not inevitable.