Archive for February, 2008

Leap Day

Phil Plait runs down the numbers about leap days, and why the Gregorian calendar has them every 4 years but skip every 100, except when we unskip every 400.

And if you find that confusing, you’re still probably not as confused as we Swedes are. The old Julian calendar didn’t have the rules about skipping (or not) years divisible by 100 or 400, so that’s why it got off track and countries started changing to the Gregorian. And while most countries just bit the bullet and dropped the 10 or 11 days (depending on when the change was made), Sweden tried to think different … and screwed it up. Miserably.

To avoid the havoc of just obliterating the large chunk of days, the Swedes decided to do it this way: just say no to leap days for 40 years, and then their calendar would be in synch with the Gregorian calendar. The problem of not lining up with either calendar didn’t dissuade them from this plan. It started out well enough — they began this in 1700, which was a leap year for the Julian but not the Gregorian calendar, so there would have been no Feb 29 with either method of adoption. But something went terribly wrong: somebody (no doubt addled by overconsumption of herring) forgot the master plan, so 1704 and 1708 both had a leap days. Rather than just go ahead with the Gregorian adoption, it was decided to go back to the Julian calendar, but an extra day would be needed, since one had been dropped in 1700. Solution? A leap day! It was added in 1712, and since 1712 was already a leap year, that meant there was a Feb. 30.

The Swedes went ahead with the Gregorian calendar in 1753, adding in the 11 days all at once.

Breaking the Speed Limit

Over at Skulls in the Stars, a good summary of anomalous dispersion (aka pulse reshaping). When a news article reports a laser experiment that supposedly shows superluminal behavior, the odds are pretty good that this is what’s going on.

Turning Physics on its Ear

So yesterday I linked to a couple of anti-relativity sites, and tearing down their arguments might be fun, as gg suggests in the comments. But that’s just the tip of the iceberg of people who have a beef with some part of physics. And the folks who think physics is in need of an overhaul aren’t limited to their own little websites, or posting to science forums. They write books, too. There’s a discussion about one such author over at Pharyngula (and the same topic popped up today on SFN) but it’s been dealt with pretty thoroughly over at the JREF forum. I haven’t read the book, so I’m not going to raise specific objections here.

But there’s an attitude that is presented, and echoed elsewhere, that the physics is wrong because it doesn’t explain things. And these people are hell-bent on explaining things. But they go about it in the wrong way — they seem to be mortally afraid of making a specific prediction. Of using math in a useful way.

A common refrain goes along the lines of X is not a mathematical model, and it does not, nor does it need to, reduce mathematically to the physics I’m attempting to supplant

And that’s the problem. It’s great that you can “explain” phenomenon A. But can you also “explain” phenomenon B, that doesn’t actually happen? If you can explain anything, then it’s not very useful. A useful explanation can’t be some vague handwave. The strength of the mathematical model is it allows one to actually calculate things. It’s not good enough to explain the bump on my graph. I want to know if the bump should be at 10 eV, because if your explanation puts it at 15 eV, then you’re wrong and need to go back and change something. Your work has to be able to be tested for being wrong in a verifiable way

The Great Deception

Over at Pharyngula there is a link to a talk summary (not surprisingly, related to evolution) that says

Evolution is the “greatest deception in the history of science”.

Wait. I thought Anthropogenic Global Warming was the greatest deception in the history of science

But, whither physics? Surely physics has foisted deception upon mankind, somehow. Ah, relativity to the rescue. Even worse than the evolutionary deception of Piltdown man, apparently

By now, science seems to be
so heavily invested in Relativity and Einstein, that it will be very
hard to admit Relativity has been so obviously wrong. It would be
like admitting to a crime.

Lies in science have happened before virtually on the level of
relativity. In England a claim was made that the origin lay in
Britain, perpetrated by leading experts in the field of paleontology.
What they did was to use a fairly modern skull, filed off key
evidence from an ape lower jaw (joints, teeth), put them together
and claimed they had found it like that. This deception has lasted
for a long time, but not as long as the Relativity deception has.

And in addition

It is simply incredible that a theory with so many deceptions has held the attention of so many of physicists and other scientists from the field of natural and technical sciences for so long, and has managed to retain acceptability and even enter the textbooks for secondary schools and universities.

Actually, relativity and evolution are deceptions that follow from the Copernican deception. Evolution was the followup, and relativity was the third blow.

Once the Copernican Revolution had conquered the physical sciences of Astronomy and Physics and put down deep roots in Universities and lower schools everywhere, it was only a matter of time until the Biological sciences launched the Darwinian Revolution.

And then, after the Michelson-Morley experiment

Einstein’s Relativity hypothesis rescued heliocentricity from the findings of over 200 experiments which showed that the earth was not moving.

I always enjoy the conspiracy angle. We have so much invested in the deception of relativity that we just can’t afford to abandon it at this point. It takes tremendous effort, covering up such a theory that doesn’t actually work. Good thing it’s just a blind alley of physics, and no science or technology actually uses it.

Interestingly, I couldn’t quickly find the same vitriol-induced confusion over quantum mechanics. Perhaps it’s just that QM is so openly bizarre that despite the fact that there are those out there that decry it, it’s not considered deceptive.

Trivia Time, part I

Trivia about time, to be precise. Prior to my current job, my knowledge of timekeeping was pretty much knowing how to read and adjust a clock, and because I’m a physicist, Einstein synchronization (basically accounting for propagation delay of light) and the effects of general and special relativity. All of the physics-related exercises with time conjure up a perfect clock, so you don’t have to worry about all the little details that arise when dealing with real-world hardware. Now, I don’t actually do time measurements, I “just” work on building clocks, but there are some things I’ve picked up.

A clock will have an oscillator in it, and some way of counting the oscillations. Time is the phase of these oscillations — one “tick” represents one cycle or some number of cycles. The derivative is the frequency, and if you take another derivative you get the rate of change of the frequency, which is the drift. Which sounds just like kinematics — the basic equation that describes all of this looks just like basic kinematics, as long as the rate of change of your frequency is a constant. And that brings up a point commonly fumbled by the popular press: leap seconds are often described as being added because the earth’s rotation is slowing. And while it’s true that over long times, the rate is slowing, that term could be zero and you’d still have to add leap seconds. The frequency represented by an earth that has slowed (but is no longer slowing) is different than that of atomic time, and so one will accumulate a phase difference (i.e. one will run slow compared to the other). That the rotation rate is slowing means that we will add leap seconds more often, assuming other effects on the rotation rate don’t mask this.

The above assumes “perfect” clocks. However, in all real processes that we measure, there is noise. Different kinds of noise, too, depending on the systems being measured. The best you can hope for is random, (i.e. white) noise, which gets averaged down as you take more measurements, and varies with the inverse square root of the number of data points (in this case, time). There are noise processes that average down faster, but eventually white frequency noise will dominate, and then the best case is that there are no other noise processes that dominate at longer times (like flicker or drift).

You integrate white frequency noise to get the effect on the phase, or time. The integral of this white noise gives you a random walk. That is, for any two real clocks, with exactly the same frequency, the best you can do is have them random-walk with respect to each other. They will never stay synchronized.

From the "What would happen if?" Files

A friend emailed me with a link about the LHC, and poses this question:

If one of their micro-black holes gets away from them, will the lab go “moob!”?

(Back when he and I were teaching nuclear stuff for the navy, it was standard practice to represent pair-production as going “foop!”)

Crackpots Are Always Right

It’s a mystery to me how tenaciously someone can hold on to a scientific proposal after it has been rigorously demolished, as happens with cranks, crackpots, woomeisters, quackademics, etc. Even after you separate out the charlatans who are trying to scam a few spacebucks out of somebody, and the ones driven by some ideology, there’s a whole host of folks who won’t let go if their pet hypothesis that disproves relativity or quantum mechanics or whatever.

The process of science is to disprove things, and most things get disproven. Benjamin Schumacher has written a nice little summary of it, and how it tends to pervade our thinking.

On occasion, some idea of ours turns out to be right, and then we’ve made a discovery. These occasions are wonderful and gratifying, of course. They are also rare, because most new ideas are wrong. The trick is to be verifiably wrong most of the time. If our ideas are verifiably wrong, then we can eventually get rid of them

The main factor that distinguishes the behavior of scientists is that scientists tend not to take it personally when contrary data is presented that slays our pet theory, while a crank takes it as a huge insult. They don’t like getting rid of their wrong ideas, except when somehow it doesn’t affect their conclusions at all.

Castle Illusion

Color memory on a greyscale image

via Daring Fireball

Silliness Pending

Patently Silly

Angular transformation of the fedora to JohnB

Happy Birthday, GPS

GPS turns 30 today

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