1

The Environment / Re: Is the greenhouse effect a stupid mistake?

« on: 17/06/2018 10:07:43 »

It isn't irrelevant when people are trying to calculate absolute surface temperature from radiative exchange alone.

Most people's dynamic bank balance is fairly close to zero - we tend to spend about as much as we earn over a year - but the actual bottom line surely includes the million you inherited, which is neither negligible nor irrelevant to your lifestyle.

The effect of climate on living things depends on the state and distribution of atmospheric water. This would be very different if the mean global temperature were 5 degrees higher or lower than at present, so I think it is important to calculate the "underlying" surface temperature of a body which is 75% water and 25% rock, heated from the inside, with no atmosphere, before trying to fit a guess at mean emissivity to a static atmospheric  model that ignores at least half of the input power.

2

The Environment / Re: Is the greenhouse effect a stupid mistake?

« on: 16/06/2018 23:12:59 »

So what happened to the primordial and radiogenic heat?

We leave where it is. It is negligible for surface temperatures, unless you are sitting on a volcano.

Only a climate "scientist" would call 90% "negligible".

3

Physics, Astronomy & Cosmology / Re: Can I store unlimited energy as pressure?

« on: 16/06/2018 23:05:50 »

That's how hydraulics works.

There are practical limits with very thin pipes, where viscosity produces significant energy loss from a moving liquid, but hydraulic jacks and pneumatic tyre pressure  pumps are familiar examples of force multiplication.

4

The Environment / Re: Is the greenhouse effect a stupid mistake?

« on: 16/06/2018 09:11:42 »

So what happened to the primordial and radiogenic heat?

5

The Environment / Re: Is the greenhouse effect a stupid mistake?

« on: 15/06/2018 23:43:12 »

According to Wikipedia, and it concurs with my recollection of long-ago geology lessons:

An estimated 45 to 90 percent of the heat escaping from the Earth originates from radioactive decay of elements mainly located in the mantle.

Some of the rest is "primordial" heat from the molten core.

So the planet is mostly warm because it is....mostly warm!

6

General Science / Re: How should I crack an egg?

« on: 15/06/2018 18:28:38 »

Best to use an egg separator - a small metal dish with annular gaps. The yolk sits neatly in the cup at the bottom and the white flows through the gaps. Chef's advice is to separate one egg at a time into a cup then transfer the white to your mixing bowl, because whilst the first dozen will separate perfectly,the fifteenth will split and ruin the entire meringue.

7

The Environment / Re: Is the greenhouse effect a stupid mistake?

« on: 14/06/2018 22:36:52 »

So if a CO2 molecule absorbs outgoing radiation at x nanometers, it also emits at x nanometers, so has no net effect on amospheric temperature. Doesn't smell right to me.

8

Physics, Astronomy & Cosmology / Re: Are there commercial applications of variable torsion springs?

« on: 14/06/2018 19:52:39 »

Since torque is proportional to the angle of twist, all torsion springs are inherently variable.

You need to start your search with a specification: some manufacturers specialise in hairsprings for watches, others tend to work at the road vehicle end of torsion bar springs, but a phone call will usually direct you to someone else in the industry if your first guess can't help.

9

Just Chat! / Re: Is there a better example of how drug-use can alter a persons grip on reality?

« on: 14/06/2018 14:52:51 »

Kekule was apparently under the influence of a rather fine wine when he visualised the benzene ring, but I don't know of any other significant advances ascribed to impaired reasoning.

Apropos the OP, there are no "rules" in science. We just write down the best mathematical model of what we observe, and see if it predicts the next observation.

10

Physics, Astronomy & Cosmology / Re: Is Einstein Wrong?

« on: 14/06/2018 14:47:22 »

It is correct to several decimal places in prctice, and makes sense in theory.

11

Physiology & Medicine / Re: How are transcatheter aortic valve replacement - TAVR - procedures carried out?

« on: 13/06/2018 12:13:25 »

Way off topic, but the problem with consuming dairy products is that half the offspring of dairy cows are slaughtered very young as they will never produce milk or grow enough muscle for beef. Oddly, many people refuse to eat veal "because it's cruel" and  most male calves are discarded as worthless. So if you eat cheese, it seems entirely ethical to use the male calves for something sensible, like replacement bits for humans.

Whilst Queen Elizabeth I rallied the troops at Tilbury with a famous speech beginning "I have the body of a weak and feeble woman..." you can continue "....but I have the heart of a bull". Go get 'em, Karen!

12

The Environment / Re: Is the greenhouse effect a stupid mistake?

« on: 13/06/2018 07:40:16 »

In summary, you seem to be saying that clouds dominate the radiative heat transfer to and from the surface of the earth. That is obvious to anyone who has ever stood underneath one, but it seems to have escaped the notice of so-called climate scientists who persist in counting fleas like CO2 and CH4 whilst studiously ignoring the H2O elephant they are riding on. Thus leading to statements like "global warming has altered the rainfall pattern" when it is obvious that the rainfall pattern is what determines global temperature.

13

Physiology & Medicine / Re: How are transcatheter aortic valve replacement - TAVR - procedures carried out?

« on: 13/06/2018 00:28:35 »

I am assured that the donors are killed with kindness. Indeed we prefer "harvested",with connotations of sunny afternoons in the hay, buxom wenches and beery suppers, to "butchered".

I have yet to meet a colleague wandering the supermarket shelves with a shopping list and a micrometer, muttering "Apparently they never have 14 mm bovine tricuspids on Friday, dear. How about a nice porcine mitral and some goat saphenous?" into his phone. But it's only a matter of time.

14

Technology / Re: could this clockwork supply a city with renewable energy?

« on: 12/06/2018 23:49:26 »

This is a great invention ,  great as a dynamo or electrical motor, I wonder why da vinci didn't invent it?

Practically every clock built before 1400, and quite a few modern grandfather and cuckoo clocks, use a falling weight as the energy store. da Vinci didn't invent it because it was already old technology before he was born.

Short-term high power interventions like Dinorwig are used to bridge a few minutes' gap until conventional coal or gas powered stations can be brought on line in periods of sudden demand. They have no value in terms of stabilising the grid against the enormous and long-duration fluctuations caused by windmills, tidal mills or solar cells. Once the grid becomes more than 20% dependent on unreliables, each new generator needs to be backed by at least 5 days' storage capacity, just as with coal, gas or diesel stations, which is why "free" electricity is actually uneconomic - the energy density of non-chemical stores is pathetic..

15

Technology / Re: could this clockwork supply a city with renewable energy?

« on: 12/06/2018 10:13:39 »

22.5 million tonnes of rock is a plug 1 km high with a cross-sectional area of 1000 m², that is, about 7 times the mass of the Hoover Dam (I would use concrete rather than loose rocks, for obvious reasons).

You might be able to cast this mass at the bottom of a 2 km deep hole x 35 m diameter, then haul it up 1000m  on the ropes BC has designed. So you need a primary shaft that will span at least 35 m and two primary bearings capable of carrying a load 1000 times greater than any bearing yet produced. These will need foundations....it's beginning to look like an order of magnitude bigger project than anyone has ever attempted.


Why do I mention the Hoover Dam? Because it works, powers Las Vegas, and is by no means unique.

16

Technology / Re: If I have a quantum car do I need a quantum mechanic?

« on: 11/06/2018 23:21:00 »

Yes. No. Maybe.

Policeman: You were travelling at exactly 100 miles per hour at the intersection, sir

Heisenberg: You are sure of the speed?

Policeman: Absolutely, no possible uncertainty.

Heisenberg: So I could have been anywhere.....

17

Physics, Astronomy & Cosmology / Re: How big must a body of water be to have tides?

« on: 11/06/2018 06:13:12 »

It's all a matter of geography. The middle of the Atlantic scarcely experiences any tidal range at all, but it's several thousand miles wide, so an inch fall in the middle will produce a 30 inch rise in the English Channel. That said, the entrance to the Mediterranean is also narrow but the Med is much bigger than the North Sea, so the tidal range around Italy is negligible - hence Venice is a very different city from Southampton!

18

Technology / Re: could this clockwork supply a city with renewable energy?

« on: 11/06/2018 06:02:28 »

A serious practical problem with deep elevators (like mine cages) is bounce at the end of the drop. This will be a problem with your discontinuous transfer of energy from the primary gear. When you brake the gear, the kinetic energy of the falling weight will dissipate in the cable, which leads to fatigue failure, or in the soft braking mechanism, which wastes energy as heat.

The entire machine replicates a pumped-water storage system in principle. In practice, although the required volume of water will be around 2 - 10 times that of your falling weight (2 for a concrete block, 7 for steel, 10 - 12  for heavy alloys of lead or uranium) the engineering of a hydraulic unit is much simpler. Installations like Dynorwig use the same machine to pump the water up or generate electricity on the way down, no loss-making gears  (you just open the sluice gate wider to meet demand) and instead of a dangerous hole in the ground and a wheelhouse full of springs, you have a couple of fish ponds which can also act as drinking water reservoirs. But you still need a huge lake to provide more than an hour's worth of electricity for a small town!

19

Physiology & Medicine / Re: How are transcatheter aortic valve replacement - TAVR - procedures carried out?

« on: 10/06/2018 17:28:27 »

Mazeltov and best wishes for a long and healthy enjoyment of your new component! You have provided the ultimate argument against vegetarianism - why waste the rest of the cow?

20

Physics, Astronomy & Cosmology / Re: Can we measure the one way speed of light?

« on: 10/06/2018 11:37:30 »

No.

ε₀ and μ₀ are measured in entirely separate, static experiments.

If the value of c depended on direction, at least one of these would have to be a vector so you would always get different values for either ε₀ or μ₀ depending on the polarity of the applied electric or magnetic field. You don't.

For anyone with a real interest in experimental physics it is worth noting that the relative values of ε_xyzand μ_xyz for some materials are indeed anisotropic tensors and the magnitude of c does indeed vary with the orientation of the material. The fact that the resulting birefringence effects are independent of the orientation of the material with respect to the fixed stars, phase of the moon, or anything else, strongly suggests that there is no aether or other universal frame of reference, so c₀ is independent of direction.