1

That CAN'T be true! / Re: holcomb generator?

« on: Yesterday at 22:18:59 »

I can't believe people can buy into this

Many people do not have even a basic understanding of science.

It's not so long ago since I saw a university biology lecturer with a PhD post this video of a perpetual motion machine on Twitter asking if it was genuine.

2

Physics, Astronomy & Cosmology / Re: How can I pass a large DC current through mercury?

« on: 24/05/2022 11:47:33 »

If you're trying to drive the mercury along the length of the groove in the plastic, with copper electrodes 1cm apart at either side of the groove as you describe, then:

The resistance of the mercury will be 19μΩ, not 4.8mΩ;
the voltage required to drive 1kA will be 19mV, not 4.8V;
the power will be 19W, not 4.8kW;
and the temperature of the mercury will rise at 0.2°/s, not 51°/s.

I'll leave someone else to calculate how many seconds it takes to eject the mercury.

3

Physiology & Medicine / Re: Why do I find it easier to run up steep hills than walk up them

« on: 21/05/2022 18:42:04 »

A walking stance begins to feel uncomfortable and I have to bend my back forward a lot

You're not making the mistake of trying to keep your heels on the ground, are you?

4

Physics, Astronomy & Cosmology / Re: Why is leg room on transport so limited ?

« on: 09/05/2022 01:14:02 »

To cram more passengers in obviously.

If you increase seat spacing and have fewer seats you lose customers on every full flight, but only benefit <1% of the population who didn't have enough legroom. It's not cost effective.

I'm 6'5", I could write a book about what it's like living in a society of shortarses, but what's the point? Like it or lump it.

5

Physiology & Medicine / Re: is psychiatric labelling complete nonsense?

« on: 19/04/2022 17:53:54 »

I think it's plain obvious I haven't said that, and nor did Smail, but even a schizophrenia diagnosis isn't necessarily what it purports to be.

https://qph.fs.quoracdn.net/main-qimg-99a7c34202a277ea8db60c8a01128864

Ok, then what did you mean by "most mental health problems are a normal reaction to abnormal circumstances"?

You've already had the answer to that question, 7% of mental health conditions doesn't constitute 'most', does it.

6

Physiology & Medicine / Re: is psychiatric labelling complete nonsense?

« on: 19/04/2022 13:07:46 »

In essence, Smail argues that most mental health problems are a normal reaction to abnormal circumstances, and therapy fails because it seeks to gaslight the patients into believing that they having an abnormal reaction to normal circumstances.

So are you saying mental conditions like schizophrenia doesn't really exist?

I think it's plain obvious I haven't said that, and nor did Smail, but even a schizophrenia diagnosis isn't necessarily what it purports to be.

https://qph.fs.quoracdn.net/main-qimg-99a7c34202a277ea8db60c8a01128864

7

Physiology & Medicine / Re: is psychiatric labelling complete nonsense?

« on: 18/04/2022 17:15:20 »

This makes an interesting read. In essence, Smail argues that most mental health problems are a normal reaction to abnormal circumstances, and therapy fails because it seeks to gaslight the patients into believing that they having an abnormal reaction to normal circumstances. The only therapist I've met who could communicate rationally without being deliberately obtuse left the job saying "I'm fed up of the way the patients are patronised, and fed up of pretending we're helping when we know we aren't".

My advice to anyone contemplating getting themselves a mental health record would be think very carefully about whether you want your healthcare blighted by Diagnostic Overshadowing for the rest of your life.

Connections by Johan Hari is a thoughtful and intelligent look at how our modern way of life creates many of the health problems that are reaching epidemic levels.

8

Physics, Astronomy & Cosmology / Re: Which weighs more, a litre of ice or a litre of water?

« on: 15/04/2022 16:15:39 »

"Houston, we have a problem. We have a leak. Our oxygen is rapidly venting"

"Hello, this is NASA Houston here. We are currently experiencing unprecedented call volume, and all our operators are busy. Please be assured that your call is important to us. If you're calling to order a pizza, please press #, otherwise hold the line and your query will be dealt with as soon as possible. You are currently number 46 in the queue."

9

Physics, Astronomy & Cosmology / Re: Which weighs more, a litre of ice or a litre of water?

« on: 15/04/2022 16:10:06 »

Although the difference between the American and the Europeon gallon causes confusion in the MPG figures there is an actual difference in the efficiency of engines because the low octane rating of the fuel means a lower expansion ratio must be used

I once told an American who was gloating about their petrol prices that a US gallon is smaller than Imperial. He didn't like it at all. Don't you know that everything is bigger in America?

10

Physics, Astronomy & Cosmology / Re: Is a unit of energy the equivalent, regardless of the way things are delivered?

« on: 15/04/2022 15:56:09 »

Boilers are typically about 90% efficient, so to get 17MWh of heat out you'd need about 18.9MWh of gas in. However the unit price of electricity is about 4.5 times higher, so gas works out a lot cheaper overall. I can heat the whole house with gas for about the same cost as heating one room by electricity.

11

Physiology & Medicine / Re: Can we train our eyes to prevent needing glasses?

« on: 14/04/2022 15:53:08 »

Many people who have bad vision have already retrained their eyes to focus on something far too close to them, be it television or something else. I believe in most cases the eyes could be retrained, but the eyes would need to be retrained to try to achieve focus.

Computers mobile phones etc are having a bad effect.

Good luck with that one, leaving poor eyesight untreated increases the risk of dementia.

https://academic.oup.com/aje/article/171/6/728/114039?login=false
https://www.karger.com/Article/Abstract/52814
https://agsjournals.onlinelibrary.wiley.com/doi/abs/10.1111/j.1532-5415.2004.52554.x
https://agsjournals.onlinelibrary.wiley.com/doi/abs/10.1111/j.1532-5415.2005.53219.x

12

General Science / Re: Do rockets violate conservation of energy?

« on: 13/04/2022 19:59:38 »

The rocket equation is: m.dV/dt = Ve.dm/dt

m is the mass
dV/dt is acceleration
Ve is exhaust gas velocity
dm/dt is rate of fuel burn

For a constant exhaust gas velocity and fuel burn rate, acceleration increases with reducing mass.

13

Question of the Week / Re: QotW - 22.03.11 - Why do electric car batteries wear out?

« on: 11/04/2022 18:36:04 »

"The four suspected renegades responsible for capacity loss and the eventual end-of-life of the Li-ion battery are:

1. Mechanical degradation of electrodes or loss of stack pressure in pouch-type cells. Careful cell design and correct electrolyte additives minimize this cause.
2. Growth of solid electrolyte interface (SEI) on the anode. A barrier forms that obstructs the interaction with graphite, resulting in an increase of internal resistance. SEI is seen as a cause for capacity loss in most graphite-based Li-ion when keeping the charge voltage below 3.92V/cell. Electrolyte additives reduce some of the effect.
3. Formation of electrolyte oxidation (EO) at the cathode that may lead to a sudden capacity loss. Keeping the cells at a voltage above 4.10V/cell and at an elevated temperature promotes this phenomenon.
4. Lithium-plating on the surface of the anode caused by high charging rates."

14

Technology / Re: Thermal radiators plus lens.

« on: 08/04/2022 14:22:30 »

I don't see any point in a lens the same size as the panel when the purpose of the lens is to focus light into a smaller area than its own. Are standard panels designed to withstand light at a higher power density than naked sunlight without damage?

15

Technology / Re: Thermal radiators plus lens.

« on: 08/04/2022 13:03:20 »

What do you want, heat or electricity? Generating electricity to produce heat is not efficient, solar PV is far less efficient than thermal solar. The most efficient panels are the hybrid ones, which generate both heat and electricity.

16

Chemistry / Re: What happens when you melt gold into glass?

« on: 05/04/2022 11:26:55 »

gold chloride

Well you learn something new every day. I'd always thought that the reason gold doesn't tarnish is that it's completely inert, and won't form compounds. Dunno where I got it from, school probably.

17

General Science / Re: Do air sealing machines really preserve our food?

« on: 25/03/2022 17:11:07 »

If food is not sealed in a freezer it will normally freeze-dry over time

Warburtons still used to pack their bread in waxed paper long after everyone else was using polythene. I once bought a loaf from a garage that was storing them in the freezer, and by the time it had thawed out it was still as solid as it had been when frozen.

You get much the same result if you put thawed and frozen bread together in the same bag before the frozen has thawed.

18

Technology / Re: How does a toaster know when to pop?

« on: 23/03/2022 14:17:26 »

They don't, that's the problem with them.

I gave up using one because the required cooking time depends on how fresh and moist the bread is, so you either have to run several test slices first just to find the right setting, or stand over it popping the toast out every few seconds to check the progress. The 'timer' on mine was just a bimetallic strip that tripped when it was hot enough, so the required setting additionally depended on whether it was the first run from cold, or the toaster was already pre-heated by a previous run.

They're as much use as a chocolate teapot, so I use the grill on the rare occasions I eat toast. I eat exclusively brown bread these days anyway, which I don't think makes particularly good toast.

19

Plant Sciences, Zoology & Evolution / Re: What is the best way to kill a hornet nest?

« on: 22/03/2022 18:54:50 »

I bought a spray can in Tesco for killing wasps nests. It squirts a jet about 8-10 feet, so you can drench the nest from a safe distance, then you just leave it a day to soak in before cutting it down and chucking it in the bin. I ignored the instructions to do it at night whilst they're all at home, so I had to do it all again after they came home to find their first nest uninhabitable and set up home again in a nearby hedge.

My father once picked a bees nest up and chucked it on the compost heap thinking it was a clump of dead grass.

20

Physics, Astronomy & Cosmology / Re: How do you calaculate the capacitance of two unsually shaped plates?

« on: 21/03/2022 17:46:38 »

The quick way is to calculate the capacitance of the wide end, then either triple it if the spacing is 2mm as in the diagram, or quadruple it if the spacing is 3mm as in the text.