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Comment Re:Yes we can! (Score 0) 210

I somehow never got this point. In the standard model, you're starting from a Lagrangian formulation of a quantum field theory, so the existence of a scalar product in the Hilbert space spanned by the theory automatically guarantees normalization of probabilities, no matter which physical values you attach to the parameters of your model. So if you're getting something larger than one, you must have made an error somewhere on the way, but that doesn't imply your entire model is wrong.

... I somehow never got this point...

Comment Re:heat (Score 1) 132

The infra red space telescopes are positioned out of the sun ('behind' the earth) in order to keep cool. However, there's still the heat from the electronics, and there's no way to get rid of that apart from by radiating the heat away. Black radiates well, hence colouring it black will keep the spacecraft cool.

In sunlight, more heat is coming in than going out, hence black cars get hot, and normal spacecraft are coloured silver (or similar) to make them highly reflective and bounce the heat off. (Even those spacecraft will often have dark surfaces on the other side in order to keep cool.)

I'm guessing that the Blackbird SR-71 got so hot with the engines, that painting it black would result in far more heat radiated than the sun would put back in. It's all a matter of balancing heat in and heat out.

The summary is a little wrong: "Because the light absorption level is so high, the super-black material will also keep temperatures down for the instruments it is used on." I think that should be "Because the heat radiation level is so high, the super-black material will also keep temperatures down for the instruments it is used on."

Comment Re:Highly Suspect (Score 2) 462

I did an experiment years ago on a 5 inch floppy disk and a fridge magnet. I had to put the magnet in direct contact with the disk surface itself before I got any corruption. If it took that much on a 1980s floppy, it must surely take much more on a shielded and enclosed hard drive.

Cathode ray tubes certainly. Used to have lots of fun making the screen change colour, until my parents got upset. But it would still take a very strong field even for that.

Comment Re:Radioactive packaging (Score 1) 277

Very interesting. We had a problem in telephone exchanges about 25 years ago. All data was held in memory - no disk drives (except for billing records I recall). Some little old granny would mysteriously acquire a premium service. It only affected the lines that were hardly ever used. It was tracked down to "alpha particle corruption", which gradually eroded the charge, which effectively flipped the bit to a 1 and gave the subscriber a random service.

Don't know any more than that, but the old hand that described it to me, did so with unusual glee...

Comment Re:Marketing tip for next time (Score 1) 602

Easy! Just infiltrate the crowd with thousands of trained trumpeters who play them 2.128ms after the person standing next to them!

Pity, that only cuts out one harmonic. However, I've occasionally had problems playing trombone next to a bass guitar. The amplified tone somehow cancels out my note and all I get is a muffled rasp.

Maybe we could have speakers concealed under the seats carefully tuned to play the exact opposite of whatever they pick up around them?

I know - how about installing colonies of African wasps trained to attack anything that sounds like them?

Comment Re:Very important first step (Score 1) 301

Don't solder on your mother's kitchen table. Or indeed anything valuable.

You need somewhere to get rid of excess solder. A damp sponge works well if you touch it briefly. Soldering iron stands usually have one in a tray on the base. If I'm in a hurry, I just use an old bit of paper, and tap the solder off. The metal isn't hot enough to burn the paper. Not so far, anyway...

Comment Re:Be prepared to be shocked (Score 1) 301

2: Relays. ... This wouldn't have been quite the problem, if I weren't using the relay to drive the relay ... which creates an oscillator. This means that I shocked myself quite a few times before I could get the breadboard off of my hand.

Made them deliberately in school. Great fun. I got ten people to hold hands and gave them all a shock just as the teacher walked up the stairs.

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