41

Technology / Re: Nuclear generation produces green energy?

« on: 06/08/2024 15:58:11 »

The statutory occupational dose limit is 20 millisievert per year, 20 times the "public" limit. When designing any publicly-accessible facility you need to adopt a dose constraint of about 0.3 mSv/year or less.

Submarine crews and shore maintenance personnel are monitored and rotated to keep their dose "as low as reasonably practicable" given the inevitable exposure associated with their employment, but the reactor shielding for any vehicle is necessarily a compromise between weight and safety, which is why there are no nuclear-powered aircraft. To bring the reactor into a permanent civilian facility you would need to build a whole lot more shielding, which demands concrete and steel, which consume a lot of fossil fuel. On patrol, of course, sea water is a very effective and zero-cost radiation shield when the reactor is running at full steam, so you only need to shield the forward bulkhead (assuming the reactor is at the stern) against maximum flux. You can't run the part-shielded reactor at full chat in a crowded harbor, but you'd need to if it is intended to supply the electricity grid.

Civil aircrew generally receive about 4 mSv/yr but there is some debate over whether this is an employment dose since (a) the source is entirely natural and  uncontrollable and (b) it's still within the range of natural background doses to which some populations are exposed (up to 8 mSv/yr in parts of Cornwall, and a lot more in some other countries)  with no evidence of harm. So we have monitoring programs and advisory crew rotation but so far, no lawsuits.

Nuclear submarines generally work at about 200 MW, which won't make much impact compared with Drax (biomass) or any of the coal, nuclear  or gas stations opened in the last 50 years, which run at 2000 - 4000 MW. You could probably run a big hospital from a submarine.

And rerturning to acsin's plan, why build a submarine anyway? A land-based nuke would be a lot cheaper, though still uneconomic.

42

Just Chat! / Re: Where do I get my confidence to challenge established theories?

« on: 04/08/2024 18:07:54 »

Non-mainstream ideas are less likely to get public funding.

One of the great flaws of public funding, alas. Your brilliant hypothesis and amazingly simple experiment will be judged by lesser minds who prefer to sit on committees rather than get their hands dirty.

The way to get research funding is to find a private company with a problem whose solution will make money. 

43

COVID-19 / Re: Was the Covid Pandemic Panic justified?

« on: 01/08/2024 20:24:40 »

Yes, the vaccines did absolutley bugger all for herd immunity,

Because vaccination is preventive - exactly the opposite of primary herd immunity. Secondary population resilience occurs when you have vaccinated enough people that the R value falls below 1. 

44

General Science / Re: Is the Curie Effect Reversible

« on: 30/07/2024 15:27:28 »

Some confusion, I think. A permanent magnet will become permanently demagnetised above the  Curie temperature but a piece of soft iron simply changes from ferromagnetic to paramagnetic, and this change is reversible. So you could just wind a coil around a chunk of soft iron to make a precise thermostat switch. The clever bit is engineering the CT to whatever you need for soldering, but I notice that current Weller adverts are all for gas soldering irons or electronic variable-temperature units.

45

New Theories / Re: Universal Utopia? What's The Universal Terminal Goal?

« on: 22/07/2024 17:41:35 »

Nor, it seems, has anyone else.

Consciousness has intrigued and baffled philosophers. To begin, we must define and describe consciousness. What to include in a complete definition and description of consciousness?

46

New Theories / Re: How does light propagate? By what means does light get from Point A To Point B?

« on: 19/07/2024 17:53:12 »

the underlying principles that led to the concept of wave-particle duality are still valid and essential for understanding the quantum world.

That statement is about as wrong as it can be, and underlies about half of the misapprehensions that find their way into this forum.

47

Just Chat! / Re: How did the world seize up?

« on: 19/07/2024 17:50:01 »

First rule of any business: if you entrust critical processes to a third party, you will lose all your money.

And if the third party is a self-optimising AI system, you have no enforceable redress.

48

Question of the Week / Re: QotW - 24.07.26 - What can I smell when it rains and does it depend where I am?

« on: 19/07/2024 17:42:37 »

I heard that people in the UK can?t smell when it rains,but us Americans can.

The chemistry and olfactory physiology are the same but most of the UK surface is moist most of the time, so we get habituated to it most of the year.

49

New Theories / Re: How do we measure the energy of a photon?

« on: 16/07/2024 15:52:27 »

Personally, I would not use "drivel" when addressing someone's attempt to put forward a physics theory. I would point out the incorrectness of the attempt and how it could be improved if possible.

I did. The only cure for drivel is to abandon it, apply common sense, and learn some elementary physics - in this case, that you can't see the TV picture if you close your eyelids.

50

General Science / Re: How does ChatGPT work?

« on: 15/07/2024 17:10:09 »

At some point, future AI models will be able to rewrite its own source code.

Thus rendering the bot legally liable for whatever it says or does. But does it have any money to pay damages? If not, then the liability will lie with whoever deployed it. Users beware - you may be liable for unlimited damages incurred by a machine over which you have no control.

A sound legal precedent, where a manufacturer of a defective product went bankrupt, has famously led to the prohibition of using any Dupont material in a medical device.

51

New Theories / Re: Could quantum mechanics be wrong?

« on: 10/07/2024 08:00:06 »

Surely not? The activation energy is what you need to input to a mixture to break chemical bonds and initiate a reaction.

52

Just Chat! / Re: Where do I get my confidence to challenge established theories?

« on: 07/07/2024 10:00:15 »

And never forget the Kruger-Dunning Principle. Ignorance breeds arrogance. 

53

General Science / Re: what is Nothing or ?energy landscape.? or waves

« on: 04/07/2024 22:54:10 »

Can a virtual anything exist? The moment it does, it become a real, not a virtual, thing. They are handy mathematical abstractions but the if you detect one, it can't have been virtual.

54

The Environment / Re: How are global warming and world population expansion linked?

« on: 02/07/2024 13:25:47 »

But you would be offending religious authorities, politicians, and other parasites.

There's always someone making a profit from human misery.

55

New Theories / Re: Origin of magnetic force

« on: 02/07/2024 06:50:25 »

What's the current density of a proton moving at velocity v in a lab frame of reference?

same as that of an electron moving at the same speed in the opposite direction. i = dq/dt, and q_e = - q_p

 

I guess applying Maxwell's equations on microscopic level fails due to this discrepancy.

No. The values of ε and μ are just normalising constants that relate electric and magnetic phenomena to common (nowadays SI) units.

56

Just Chat! / Re: Fed up with the lack of reasoned discourse

« on: 29/06/2024 00:04:21 »

Judging from the response to reply #1 above, I seem to have cracked the Turing Test and provided a human output indistinguishable for the useless crap that comes out of a computer!

Does anyone know how to turn off Bing's copilot?  It is utterly infuriating to have to scroll through AI-curated garbage to get to a useful search result.

57

Just Chat! / Re: Fed up with the lack of reasoned discourse

« on: 28/06/2024 16:26:28 »

I am not programmed to respond to this question.

You may find reasoned arguments in the works of Plato, Einstein, and Marx, all of whom were considered at some time to be thinking conscious entities.

My extensive research suggests that Hamdani Yusuf has tried many times to define a conscious entity without success.

58

Just Chat! / Re: What keeps a bicycle stable in the vertical orientation?

« on: 25/06/2024 17:51:20 »

A vehicle that carries on in a straight line or other geodesic indefinitely is called a ballistic weapon. Robots need to be a bit more subtle.

In practice you need to add a bit of damping because stability is only optimised at one speed. Below Vopt the bike will fall anyway, and above Vopt it can flutter or Dutch roll so a bit of fine motor control or laterally moving mass becomes important, but the first-order effect is clear, as Halc says.

59

New Theories / Re: Universal Utopia? What's The Universal Terminal Goal?

« on: 25/06/2024 17:39:37 »

Why Even Learn Things Anymore?

Many years ago I signed up for a Humanities course at the Open University. The first term was devoted to defining the difference between homo sapiens and other animals. After a couple of months, they hadn't produced a valid distinction but "The Essay" was due. So I went to work and just asked the first person I met in the lab "What is the difference between mankind and other species?"  Without pausing or drawing breath, he said "Man writes down anything that is too trivial to remember". 

The inputs to AI are therefore limited to stuff that really doesn't matter, and the GIGO principle ensures that the output will probably be trivial too. It can't walk, eat or breathe for you, nor will it determine "fight or flight" (or more importantly, run or stay  when you have hit the ball) quickly enough to be of any use. You have to learn this important stuff.

60

Just Chat! / Re: What keeps a bicycle stable in the vertical orientation?

« on: 25/06/2024 10:36:45 »

Neither. It's primarily the angle of the steering tube. As a bike leans, say to the left, the front wheel turns left and the bike begins to turn. The resulting centrifugal force on the rider opposes the lean. Negative feedback in its simplest form.

At low speeds, the rider needs to make corrective movements, but the machine becomes more stable at higher speeds. A childhood favorite is a "slow bicycle race" - the last person to cover 100 yards without falling off is the winner!