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Physics, Astronomy & Cosmology / Re: Is there a limit to how hot things can get?

« on: Yesterday at 22:39:37 »

Not if the total power emitted by the fly doesn't change at all with its temperature.   Suppose it always emits  1 W of radiation regardless of the temperature of the fly.

Then you have discovered an insect that does not obey Stefan's Law, and may therefore be an alternative explanation to the Big Bang. The universe was created by a mathematical housefly!

The forum doesn't need to confuse people with complications.

That's half the fun!

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Physics, Astronomy & Cosmology / Re: Is there a limit to how hot things can get?

« on: Yesterday at 22:37:09 »

Is the thermopile powered, thus allowing you to deduce the electron flow, or is it passive, thus meaning you do not know the temperature of it?

A thermopile is a series of thermocouples. If you know the temperature of one set of junctions then the voltage across the  others depends on their temperature difference - no external power involved. But if you break the circuit and inject some current you can raise the temperature of the assembly by ohmic heating. Come to think of it, I'd probably use an auxiliary heater, even simpler.

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Just Chat! / Re: How to contact a scientist?

« on: Yesterday at 13:50:41 »

Can you present yourself? Essential. There is no point in discovering, measuring or inventing something if you can't explain or sell it to others. Writing, lecturing and face-to-face communication is vital.
 
What subjects are you studying / did you study and why did you choose to work in this field? Physics, with a bit of chemistry, mathematics and biology. These are the fundamental tools and knowledge bases of all sciences.

What are your achievements and publications? Few publications, but I built a national primary measurement standard and designed about a thousand medical imaging facilities.

What are the biggest challenges that you faced during your scientific career? Consensus, and official inspectors with severe Kruger-Dunning syndrome. "Proof by assertion" is not science.

How and why did you become a scientist? Can you present your studies and motivations? Total fascination with how things work, from a very early age. Too short-sighted to become a test pilot, too bored by biochemistry to be a doctor.

Is money a real problem when conducting projects for instance experiments? The problem in the UK is "raising the first million". Small project funding isn't too difficult and banks will lend against the security of your house. Major investors (pension funds and the like)  want safe investments in  the tens of millions. The gap needs filling by venture capital but VCs are always chasing fast growth and a quick sale, not clinical trials and flight testing. American investors and German banks are better, which is why innovation flies abroad.
 
Do you have to deal with deadlines or are you ''free'' with your work? There are no open-ended funds but I can propose delivery dates. Sticking to them is good for the reputation.

What do you plan for the future / what are your new goals?  To see corrupt officials burn in Hell.

Eventually, would you advise students to become scientist? The closer you look, the more there is to see. If you have a hint of skepticism, an ounce of self-confidence, and a ton of curiosity this is the career for you. With any luck you may use science to improve the lives of others: civil engineers save more lives than anyone else on the planet, and doctors and nurses appreciate an occasional improvement in their equipment.

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Technology / Re: Should games be used to train the military?

« on: Yesterday at 13:24:30 »

One of the first air combat games I saw was installed in the bar of a flying club. It was promptly removed when an ab-initio student destroyed the Chief Flying Instructor, DFC. 

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Just Chat! / Re: Initials grammar...

« on: Yesterday at 12:38:56 »

The appearance of penises in Hansard is, I think, rare and very recent. Honorable Members are mostly what that publication would probably call "compulsive masturbators" but, aside from a lust for lewd tractors,  they tend not to parade it in the Chamber.

Any such reference in The Times would be in a medical or court report and thus a statement of fact, not a joke.

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Physics, Astronomy & Cosmology / Re: Is there a limit to how hot things can get?

« on: Yesterday at 12:24:34 »

The spectrum is irrelevant. As long as the source and detector are coupled and isolated from the rest of the universe, heat always and only flows from a hotter body to a cooler one.

If the voltmeter is broken it will show V = 0 all the time. I've skimped on the experimental details a bit because the thermopile needs a cold reference, but you can use ice/water if the fly is at room temperature (that's actually the answer the interviewer was looking for - it's a coldblooded creature!)  so V > 0 and over a short range, directly proportional to Celsius temperature.

There is a good reason  most flies have black bodies: optimum heat exchange to keep the enzymes working and dump waste heat from the muscles.

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New Theories / Re: what is temperature?

« on: Yesterday at 00:18:15 »

 As it happens I don't think there is a good theoretical model for porridge.  As such Goldilocks probably can't determine the temperature of her porridge on the modern (post 2019) kelvin scale.   That temperature is simply "unknown" or "undetermined" at this time.

Things aren't quite that bad. She may not find it easy to calculate, but it's very easy to measure with a thermometer calibrated in K.

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

« on: Yesterday at 00:03:14 »

I don't know. The over population today, if we set a limit of one billion people as a sustainable goal, means that out of eight people existing today only one can remain, let's say 2050. But then we have projections as " World population projected to reach 9.8 billion in 2050, and 11.2 billion in 2100 "

But if we stop making babies tomorrow, the human population will decline to zero by 2122. So we have a choice, including the option to reduce the population to an indefinitely sustainable level, by doing nothing.

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

« on: 15/05/2022 23:58:09 »

Well, Alan, you didn't answer my question.Do green house emissions matter?

Greenhouse gases certainly matter. Water is the principal variable that determines the temperature of the earth's surface (even IPCC says so!). Carbon dioxide has some effect but above 200 ppm its absorption spectrum is almost certainly saturated. They are closely coupled, as the historical record shows: an increase in temperature generates an increase in atmospheric CO2 (see the Keeling curve seasonal fluctuations), which is counter to the rate of anthropogenic emission (we burn less fuel in summer).

Most important: climate change is beyond human control, so it is imperative that we mitigate its impact on human society.

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Physics, Astronomy & Cosmology / Re: Is there a limit to how hot things can get?

« on: 15/05/2022 23:49:23 »

If the thermopile is heating up, then it is doing so by gaining energy from the fly or whatever.
And that means the fly is cooling down.
So you are not measuring the fly, you are cooling it.
If the thermopile is cooling then you are warming the fly.

You are beginning to see the picture.
Now what do you deduce if dV/dt = 0?

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Physics, Astronomy & Cosmology / Re: Is there a limit to how hot things can get?

« on: 15/05/2022 16:21:55 »

You look at the thermopile voltage and rate of change.

V α T_thermopile

dV/dt α ΔT (thermopile - fly)

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Just Chat! / Re: Initials grammar...

« on: 15/05/2022 16:11:37 »

Passionate? Poignant? Debate?  Every major publication has a style manual. Most scientific publications use a version of the Library of Congress indexing standard, and the UK civil service (including Hansard) generally refers to The Times as a working standard.

You might however like to twist your own knickers over your own "W C Fields' "  or "W C Fields's".

Many classic 12-bar blues were written by W C Handy. Always a fallback to warm up a new band, my old bandleader used to say "When the band's playing like sh1t,  it's good to have a WC handy."

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Physics, Astronomy & Cosmology / Re: Is there a limit to how hot things can get?

« on: 15/05/2022 16:05:25 »

Nowadays, yes. The question was put to undergraduates in 1963. And it still doesn't answer HY's problem of not extracting energy from the object.

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

« on: 15/05/2022 16:02:52 »

You can build a lot of logic on a false premise. Problems arise when your action plan fails to deliver because your premise was irrelevant to or insufficient for the problem. Have another look at #33429 above.

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

« on: 15/05/2022 15:40:08 »

A simple definition would be that if we get rid of this overpopulation, everything will turn back to normal.

Obviously not, because there is no normal. The European climate of the 1960s was desirable but Bihar and Biafra suffered famines.

A smaller human population could tolerate a less favorable climate, and even enjoy the present climate more. That's Plan A - resilience.

Plan B must involve the orderly elimination of fossil fuels, obviously because of their finite supply (i.e. sustainablity), but more urgently because they make democracies dependent on dictatorships.

Even if the climate were to play nicely, we can't sustain a desirable standard of living for the present population without fossil fuels, so we need to implement both plans.

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

« on: 15/05/2022 15:37:54 »

What have I denied? The facts are undisputed, but the consensus mechanism behind them doesn't make sense. So I'm skeptical about the consensus.

That's how science progresses. Nobody ever denied that the sun rises every morning, but the skeptics suggested that maybe the earth rotated, not the consensus sun. Who was right? 

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Physics, Astronomy & Cosmology / Re: Is there a limit to how hot things can get?

« on: 15/05/2022 15:23:25 »

How do you detect it if energy is not leaving the system?

When you don't detect it coming or going, it isn't transferring. Therefore the subject and the reference must be at the same temperature.

A clever way to do this (at least in principle)  is to put your sample and a small thermopile at the foci of two spherical mirrors facing one another. You heat the thermopile by passing a current through it, and measure its temperature by measuring the voltage across it when you switch off the heating current. If the sample and the thermopile are at the same temperature its voltage won't change with time immediately after switchoff.  But as I remarked elsewhere, practical heat experiments are very difficult to do!  The experiment was originally devised in response to an interview question:how would you measure the temperature of a fly?

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Just Chat! / Re: A Short puzzle with dogs.

« on: 15/05/2022 09:40:34 »

I've always wondered whether "proper" mathematicians allowed the use of obvious symmetry and reflection as tools in a formal proof. I was so inspired in my youth by Kasner and Newman's "Mathematics and the Imagination" that I married the only girl I ever met who shared that enthusiasm (both, it turned out, recommended by our electrical engineer fathers). Like a good novel, it began with a surprise - the use of obvious symmetry to simplify a classic proof.

The dog and river problem actually has a practical application in navigation. If you are sailing or flying to a visible destination with an unknown cross wind or tide, simply aiming directly at the target will take you on a spiral pursuit curve, arriving pointing directly into wind. The trick is to maintain your original compass heading for half the distance, then turn through four times the difference between that and the new bearing. It's oddly counterintuitive but definitely optimal.

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

« on: 15/05/2022 09:21:38 »

that deniers and skeptics will use to once again 'prove' that we have nothing to worry about.

As a skeptic, I can demonstrate that we have plenty to worry about - assuming that the collapse of human civilisation is worth worrying about - and tinkering with carbon dioxide emissions isn't going to solve the problem or even have a significant impact on it. Indeed in the short term it may even increase inequality and political tension.

All living things destroy their environment. It's the essence of life processes. The trick is to find another living thing that can repair the damage, and to adjust the populations of both to achieve a sustainable equilibrium. Humans are uniquely able to  do this prospectively, and still too stupid to do it.

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Physics, Astronomy & Cosmology / Re: Is there a limit to how hot things can get?

« on: 15/05/2022 09:11:00 »

Depends on what constitutes temperature? Is it on atomic level or subatomic level, is the temperature considered to be on the substance in question or the measuring device. For example how could you ever measure temperature without the substance in question loosing some energy.

Temperature is the mean internal kinetic energy of a mesoscopic body. It has no meaning for an individual particle.

You can in principle measure temperature without net heat loss by detecting the heat flow between the subject body at T_S and a reference at T_R. when there is no flow, T_S = T_R.