1

Physics, Astronomy & Cosmology / Re: Can a wall of mushrooms absorb harmful gamma radiation?

« on: Today at 15:46:57 »

It is conceivable that chaga mushrooms may absorb and concentrate radioactive heavy metals in the soil, just like Brazil nuts, but they can't "eat radiation" in the sense of absorbing gamma radiation from a distant source, any better than any other material.

Lead is OK for absorbing gamma radiation but at high energies (above 100 keV) it is the mass of material rather than its atomic number that determines the effectiveness of a gamma shield, so you may as well use a structural material like steel, which can serve two purposes, The silica tiles will mop up most of the low energy gamma and charged particle radiation.

Neutrons will happily penetrate silica and steel, but are strongly absorbed by hydrogen so an inner layer of water or polyethylene would be useful.

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Geek Speak / Re: Should I react to these threats

« on: Today at 15:29:25 »

Ask for their bank details, then call the police. But don't respond via their website or email - use a public telephone only. If no phone number, just note the IP and call the police.

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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: Today at 15:28:11 »

I progressed from there to the idea that “reality” is made up of a “series of snapshots”. 

This is not possible. If a rock were to roll in a series of discrete jumps you would need to apply an infinite force for an infinitesimal time, first forward and then backward, to make it do so.

The assertion is the basis of Zeno's paradox and as with every other paradox, it is founded on philosophy rather than physics. Unfortunately the adoption of digital information processing has led to many similar misconceptions, including the redefinition of a circle as 360 straight lines and the notion that the human eye has a consistent scan or frame rate.

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Physics, Astronomy & Cosmology / Re: Why Gauss Meters are considered so reliable?

« on: Today at 15:21:29 »

A gaussmeter measures the field in its detector area. You can't blame the meter for your choice of an inhomogenous field! Try putting the sensor in the middle of a long, tightly-wound  solenoid - you should find the indicated field varies very linearly with the solenoid current.

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Physiology & Medicine / Re: Does higher education promote mental health?

« on: Yesterday at 20:12:52 »

There is little doubt that a high level of vocational education can lead to a satisfying career, money, stability, control, and all the other things that promote mental health.

Interestingly, the stress of running a huge engineering project, practising neurosurgery, or captaining a ship or plane, seems not to be harmful because top professionals are in charge. The people who suffer from stress are whose who cannot control their deadlines or select their inputs - generally, those in any organisation with the least or least relevant qualifications.

A nice example was seen on a recent TV vox pop. A young carpenter, who had been trained by his dad, was running a small building firm, making lots of money, and thoroughly enjoying the buzz of business. A woman complained that, having an upper second degree in English literature she could only get stressful, low-paid employment as a primary school classroom assistant. The carpenter said "what did you expect to do with a degree in English?"

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Physics, Astronomy & Cosmology / Re: How viable is Elons Hypa Loop

« on: Yesterday at 07:50:02 »

The original Atmospheric Railway dates from 1799.

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Technology / Re: Cool.. Weird.. New Stuff!! (or future stuff...)

« on: Yesterday at 07:38:37 »

Laptops that can charge battery via typing on keyboard.

I think it's called a manual typewriter, or possibly a mechanical calculator. Been there, done that, for a living!

Flexible photos of kids and cats? We used to print them on paper.

Wooden USB....

And I see the wooden stick is coming back into use. Wonderful weapon-cum-heatsource - utterly reliable in all conditions. If you have two, you can light one and use the other to hold the bread  - transparent toaster!

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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 10/12/2018 21:12:40 »

The bit between birth and death is called life. You can count  the clock ticks if you like, but generally the earth goes round the sun between 50 and 100 times. History suggests that this sequential and repetitive event is not affected by the death of anyone.

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Physics, Astronomy & Cosmology / Re: What does the term 'time' relate to in time dilation?

« on: 10/12/2018 16:30:40 »

Time is what separates sequential events. If we build an atomic clock, we know that the separation between sequential events is absolutely fixed by the nature of the internal fields of the atoms.

Now we place the clocks in different gravitational potentials. Each appears to run at a different rate from the point of view of the other. The difference is calculable and experimentally verifiable.

Any further discussion rapidly becomes philosophical or metaphysical and therefore pointless intellectual vanity, by definiton.

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Technology / Re: How to detect stealth aircraft?

« on: 10/12/2018 13:23:35 »

A few hundred watts of radar kit may light up the fuselage a bit, but a megawatt of burning kerosene leaves quite a trail of hot gas behind it.

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Technology / Re: How Does A Smoke Detctor Detect Smoke ?

« on: 10/12/2018 13:14:59 »

 A gram of americium 241 emits 130,000,000,000 alpha particles per second.

About 0.3 microgram is entirely enough, and allows for small quantities of smoke detectors to be scrapped as nonradioactive electronic waste.

David Hahn, inter alia, generated neutrons by using Am241 sources to activate berryllium substrates, with a view to initiating a chain reactionin his garden shed.

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Just Chat! / Re: How can we help our American allies in the war on the Moon

« on: 09/12/2018 20:26:10 »

It is very difficult to understand the origins of WWI from a modern perspective. Why was Archduke Ferdinand so important as to merit the deaths of tens of millions, when musicians and US presidents can be assassinated with no secondary effect?

13

Technology / Re: How to detect stealth aircraft?

« on: 09/12/2018 20:18:36 »

All fast jet aircraft emit hot gas. I'm fairly certain than an infrared-imaging satellite could track the CO2 plume, particularly as they all start from known land bases or very large ships.

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Just Chat! / Re: How can we help our American allies in the war on the Moon

« on: 09/12/2018 15:45:41 »

The American Way in warfare is to turn up late and take all the credit (WWI, WWII), lose (Vietnam), or back the wrong side (Afghanistan, Syria, Iraq....). I see little future in coming to their aid anywhere, anytime.

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Just Chat! / Re: If religion gives one comfort is it...

« on: 08/12/2018 10:26:03 »

In other words, christians are morally no better or worse than anyone else, but better organised than most.

You still have the problem  that whilst a common belief in a deity can help to organise people who want to do good things, it also provides an excuse and motivation to do evil things.

An apology cannot  excuse or undo centuries of abuse committed in the Name of the Lord. The abusers will rot in Hell, along with any who seek to justify or diminish their actions retrospectively. And it is their fault for inventing Hell.

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Physics, Astronomy & Cosmology / Re: Can UVA and UVB rays pass through a wood ply roof with a bitumen felt covering?

« on: 07/12/2018 10:42:09 »

No.

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

« on: 07/12/2018 07:49:06 »

Going back a paragraph or two, the problem  with communist countries has been the introduction of a command economy, where production targets and product standards are set centrally. This leads to all sorts of problems including the failure to develop or embrace new technologies (because they aren't necessary to meet the current production standard), overworking of land (because reaching today's target is essential and the price is fixed, so you can't have a "bad harvest" or rotate the crops - just pour on the fertiliser or lie about the yield) and Really Big Cockups because the project can't be delayed or raise extra funding to cover unexpected problems (so the plane falls out of the sky in front of the Great Leader).

This is quite different from socialist states where essential public services and primary industries are tax-funded or part-owned by the government. It would be difficult to class any part of Scandinavia or indeed most of western Europe as non-viable: trains run cheaply, on time, and nobody is bankrupted by medical bills; but if you have an urge to make handbags or space rockets, or grow exotic mushrooms, you can sell shares in your dream and have a go at anything you like.

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Just Chat! / Re: If religion gives one comfort is it...

« on: 06/12/2018 00:51:28 »

You don't even need the test of "reasonably" foreseeable. If your god is omniscient, he must have foreseen everything and is therefore liable for all that harms you, including congenital syphilis - just one small creature of the creator. If he isn't omniscient, he is of no value as a god.

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Physics, Astronomy & Cosmology / Re: What is a moon of a moon called?

« on: 03/12/2018 10:15:24 »

A moon's moon is a rock.

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

« on: 02/12/2018 23:52:23 »

"God's morality" dictates whatever you want it to dictate. That is the reason for inventing gods.

There has been a lot of confusion here between socialism and a command economy - by no means synonymous. The essence of socialism is "from each according to his means, to each according to his needs". Provided that your tax system is fair and not a disincentive, and your benefit system meets all and only basic needs, you can rely on most people's desire for acquisition and comfort to propel a very pleasant and sustainable  society, as in Scandinavia.

Things go wrong when the state dictates rather than provides. Committees are fairly good at responding to demand, but not at predicting it, nor at innovating solutions or changing direction when things go wrong. The best disasters occur when the product must be presented to the dictator on a fixed date - prototype planes fall out of the sky and unripe corn is harvested to meet the command target, where in a less centralised society a test pilot or farmer can say "let's give it another week" and the shareholders realise that a duff product won't sell in a free market. Common sense (usually) prevails in our constitutional monarchy, where the "official opening date" is rarely set before the actual service commences.