An Eccentric Anomaly: Rant

Ed Davies's Blog


Pages tagged: Rant

The many things that wind me up

Water Vapour and Relative Humidity

It's often said that 100% relative humidity (RH) corresponds to the amount of water vapour that the air can hold at the relevant temperature. I think some people have an image of the air being like a sponge and when all the little holes become full and the air becomes saturated the rest drips out. This is wrong and, in some cases, seriously misleading but just close enough to right in common cases that the myth keeps getting repeated. Part of the problem is that the easiest way to phrase discussions reinforces the idea.

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Cryptography, Blank Minds and the Law

This afternoon I had a little crypto-fright, forgetting an important passphrase for a while.

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Wider Encryption Considerations

Yesterday I wrote some comments on the UK government's response to a petition submitted to the parliament web site on encryption. Those comments were rather specific to the general technical issues with the response.

I'd also like to make some wider comments.

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RevK's Encryption Petition

Adrian Kennard submitted a petition to the parliament web site asking (implicitly) that the government not ban strong encryption. I and about 11'000 others signed this petition so the government felt obliged to respond.

Regrettably, they didn't seem to feel the obligation to make much sense in the response.

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Is Tony Blair a War Criminal?

Both more specifically and more generally: did Tony Blair, the rest of the British government, a large proportion of Parliament, a swathe of the civil and diplomatic services, the monarchy and the military commit a war crime through their involvement in the planning, preparation, initiation or execution of the 2003 invasion of Iraq?

IANAL and I'm struggling a bit with some of this stuff but I think that, strictly speaking, they did not though only because waging a war of aggression or a war in violation of international treaties is not a war crime but rather, to use the terminology of the Nuremberg trials as it has entered current international criminal law, a crime against peace. Rudolph Hess's conviction is a relevant case; he was found guilty of participating in waging aggressive war but not guilty of war crimes (or crimes against humanity).

The distinction is a bit pedantic but it does have unfortunate consequences for the legal situation in British law and for jurisdiction in international law.

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A Rant About Kilograms On Mars

The CACM have published a reasonably interesting article by Gerard J. Holzmann about verification of the software on the Curiosity Rover: Mars Code.

Near the beginning, though, it says:

On Earth, Curiosity weighed 900 kg. It weighs no more than 337.5 kg on Mars because Mars is smaller than Earth.

Nope!

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Heatloss Calculation

My house designer is, understandably, a bit concerned about how he'll put the rather unconventional heating arrangements for my house into the SAP software. The other day we were discussing the emitters (radiators) involved and talked briefly about the size that would be required if we were to ignore the heat leakage from the thermal store which should in practice supply a lot of the background heat needed.

To get a grip on this myself I decided to update my heat loss calculations to the slightly evolved design of the house and to allow for the regulatory requirement that the emitters should be sufficient to keep one apartment at 21 °C and the rest of the dwelling at 18 °C.

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Bye Bye, Skype

I've cleared out my Skype account and will not be using it further. There doesn't seem to be an obvious way to delete the account otherwise I'd have done that, too. Here's why…

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David Rose Again

David Rose is at it again with this article in the Mail on Sunday. As with last time lots of people have expressed their displeasure at various points. To find this commentary a good place to start is the update to and comments on the post from which the graph at the top of the article was originally taken (here) but replaced with Comparing global temperature observations and simulations, again by Ed Hawkins on the Climate Lab Book blog.

I just want to focus on an answer to one particular point. More...

Which is more scary: volts or amps?

It both amuses and scares me how people are frightened of high voltages but often seem amazingly relaxed about low-voltage high-current situations.

High voltages are relatively easy to deal with. Wrap them up so people can't contact them with bodily parts and put an over-current protection device (fuse or circuit breaker) in the way so they're not likely to start a fire. For extra points, put an RCD in the circuit to defeat those more intent than normal on a Darwin award and even an AFCI to stop relatively small sparks causing fires.

High current circuits, particularly DC ones, are intrinsically harder to make safe even at low voltages as any poor connection, with higher than nominal resistance, can dissipate significant amounts of power as heat and so, maybe, cause a fire. Over-current protection doesn't help as normal operating currents can cause such problems.

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