illuminating science

Hope everyone has a happy Christmas, and enjoys a bit of R&R over the break!

Given this festive time of year, I thought we should think about a problem close to the heart of many children - how does Santa get around and deliver all those presents in one night? I think the best explanation is through special relativity. Note only does that article solve many of the mysteries of Prof. Claus, but it also has some really interesting physics in it! (My one gripe is a little technical: Santa doesn’t gain mass as he speeds up, no matter what E=mc² might appear to say. I’ll have to explain that in another post, but trust me - our Santa doesn’t add any more kilos to his cheerful figure!)

Other fun discussions include working out how much energy Santa must use during his trip (strongly suggesting new physics might be involved…) and an argument against the existence of Santa - but of course we know that there must be a flaw somewhere!

I’m having some time off between now and New Years, so posting may be a little sporadic. Again, have a great Christmas and I hope that Santa Claus does manage to solve his equations and bring you something nice!

Although most studies to date on the health risks of mobile phones find no conclusive evidence, a new study has found mobile phone radiation damages lab DNA. What that means is that when they exposed cells (cultured in the lab) to the same signal level that we regularly receive, it caused the individual strands of DNA in the cells to break more often than normal. While this does happen normally, and is usually repaired by the cell, this would increase the chance of a cell malfunction.

This should be treated with some restraint, though; they haven’t proved that it causes damage in actual living humans. They also haven’t published their results in a peer reviewed journal (that is, a journal where other scientists have checked the work and agreed that their methods and results are sound) so we can’t be absolutely sure that there’s not some error in their work. And just because we talk about “radiation” from your phone doesn’t instantly mean it’s harmful - light is a form of “radiation” too!

All the same, and as many people counsel, it would be sensible not to use a mobile phone more than is “necessary”. For example, even if you get half an hour of free calls a day, use your landline if it’s available, rather than using your mobile constantly. But equally, don’t feel that you can’t call your friends or family to find out where they are, or to chat when they’re out! As more research is conducted, we’ll be better able to assess the risks and learn how to counter them.

Now this is the sort of thing that astronomers must live for! NASA plans to hit a comet with a projectile, then study the debris that the impact will give off. Although it might sound somewhat violent, we currently know very little about comets, particularly about what lies under their surface. Are they clumps of dirty ice (the most popular theory)? Or some other structure? What we learn about this comet, Tempel 1, will tell us about how the solar system and the planets formed, and increase our understanding of the universe.

Oh, and in case you’re worried about knocking the comet off course (towards Earth even, as most movie producers are probably considering at the moment!) then you can breathe a sigh of relief. The comet is so big compared to the probe they’re crashing into it that it would be like a bug hitting the windcscreen of a semitrailer - that comet’s going to keep on doing what it’s doing!

Slashdot is reporting on a mock trial between a supposedly self aware computer and its “owners”, a corporation that used the computer for customer service calls. The article is a little long winded, but the initial discussion about the trial is very interesting.

There are lots of fascinating questions that arise from this sort of thing. If a computer can be programmed to respond intelligently and emotionally to a question, does it really have emotions and intelligence? (The affirmative argument is the Turing test, and Alice is the best we’ve got so far.) What if we start with a blank slate and teach the computer how to respond? Is that different? In the end, the software still tells it what to do. How do you know if your friend really has emotions and intelligence, or if he’s just programmed really well? Lots of interesting points of view in the Slashdot discussion as well.

Science, one of the top journals in the world, has published a list of (in their opinion) the most important scientific achievements of 2004. Now, I know that just a couple of days ago I quoted Hawking saying that you just couldn’t tell this early, which I still agree with, but it’s still interesting to see what achievements have had the greatest impact so far.

Heading the list is the discovery by the Mars Rovers that Mars used to have abundant water, and so potentially could have supported life. (Of course, we haven’t proven that life did exist - just that it could have. But this is still very exciting - it justifies looking harder for real evidence of life!)

Second on the list was the discovery of a new human species, “hobbits” (or, more precisely, homo floresiensis) which were only a metre high. The debate as to the species’ place in the human evolutionary tree is ongoing, with even the editor of the journal Nature suggesting that some of the species might conceivably still be alive somewhere today.

Other notable achievements include the first successful cloning of human embryos by South Korean researchers (though the embryos were not allowed to develop), the discovery of two neutron stars in orbit of each other which will allow precise measurements of Einstein’s theory of relativity, and work by Australian scientist John Mattick on the role of so-called junk DNA. Once thought to have been useless genes left over from the evolutionary process, Mattick has demonstrated convincing evidence that they play an important role in “regulating” DNA - perhaps ensuring that your finger grows to exactly the right length. More details here.

Another big year for science!

No, I’m not just trying to grab your attention! I stumbled across an article in the Wikipedia on the
evolution of sex. As in, why did we evolve sexual species (where you need two partners to reproduce) as opposed to asexual reproduction (where every creature is able to reproduce by themselves, effectively creating “clones”).

The point is that from a naive viewpoint, asexual reproduction is far easier - you don’t need to search out a partner, and your species can grow in numbers much more rapidly. However, sexual reproduction lets you evolve far easier to a changing environment, as well as distill out the best genes.

Of course, you then need to motivate the members of your species to actually have sex - which is presumably, and with all tact here, why it’s generally a pleasurable experience!

The New York Times has a (relatively) brief interview with Stephen Hawking. Ridiculously titled “The Science of Second-Guessing”, there are some interesting answers. Recall that Hawking, a brilliant physicist, suffers from motor-neuron disease, and is confined to a wheelchair, able to talk only through a computer which he controls by a single button in his hand. As such, composing answers is very slow, which is reflected in the interview - his answers are short, sweet and to the point.

He dismisses the importance of I.Q. (”People who boast about their I.Q. are losers.”, although he does hope that he is “near the upper end of the range” of intellects!) and I thought his answer to “What is the most important physics idea this year?” was particularly sensible: “We won’t know for a few years.” Although we would love to be able to announce that so-and-so’s theory is revolutionising physics, etc, it generally takes a few years for scientists to fully debate the correctness, worth and implications of a proposed theory. And it may take many more years again before it true impact is observed - just think of the laser! And nowhere is this more obvious than in the awarding of the Nobel prizes, usually many years after the theory’s first publication.

US researchers have created a plastic lens modelled on an octopus eye which can focus light five times more strongly than a human eye. The main benefits of this type of lens is that they weight only a quarter of normal glass lenses, and are soft - meaning they could be adjusted (e.g., re-focussed) simply by bending or squeezing them. This could result in better and lighter cameras, and in light, flat glasses to correct human vision. Yet another example where biomimetics (copying nature for our technology) serves useful!

A group of gamblers have won more than a million pounds (around US$2 million or AUD$2.5 million) by using a laser scanner to beat the roulette wheel. Apparently they used a laser scanner to judge the speed of the ball as it moved around the wheel (the same technology as is used in speed guns by police, or to measure the speed of serves in tennis) then fed this data into a computer, which analysed it quick enough to be able to predict which numbers were most likely to come up. All this, amazingly, happened before the wheel had spun three times, after which no more bets are allowed. And even more amazing, the police decided that this was legal, and that they can keep their winnings!

People have always wanted to use maths or physics to beat the system. Card counting in blackjack can be moderately succeessful (where you track what cards have already been played, to better know the odds of getting the card you want) but casinos watch for it, and may kick you out. (Terrible, isn’t it?!)

One popular but fatal system for Roulette is the “Martingale” strategy. Let’s assume that there’s no zero on the wheel - the only two choices are red or black with even chance. Say you always bet $1 on Red: win, and you get double your money ($2). You’re up $1 and you go home happy. If you lose, you double your bet to $2. Now if you win, you’ve get $4 and so are again ahead $1 (as you’ve bet $3 in total). Basically, you double your bet every time you lose so that you win all your money back, plus $1. And you’ve got to win once, sooner or later, right? You’re guaranteed to win! Hmmm…

Sounds perfect, doesn’t it? This strategy works in theory, only if you have unlimited money. Otherwise, you may quickly run out of funds or reach the betting limit of your casino. Then, you’re out of luck and the system fails! For instance, when using the above strategy to win, say, a hundred dollars, a losing streak of 5 bets means you’re up to $3200. Another loss, and it’s $6400. It only gets worse from there!

So, the bottom line seems to be that while mathematics might not give you the edge, a degree in physics seems to work quite well!

With President Bush strongly pushing for a return to the moon and, ultimately, for crewed missions to Mars, and with private spacecraft quickly becoming a reality, people are starting to consider the implications of commercialisation, tourism and even colonisation of our solar system.

Space exploration could be a very lucrative venture. Not only is there the potential for tourism and patriotic (and controversial!) acts like flag planting, but the solar system is expected to be abundant in natural resources, such as oxygen, hydrogen and water (to supply rocket fuel) and rich deposits of copper, nickel and other metals. The bottom line is that if it becomes profitable to travel out, mine these metals and return home, then it will be done. And sooner rather than later, I expect.

What I find most concerning is comments like “The solar system is like a giant grocery store. It has everything we could possibly want.” and “The solar system’s seemingly limitless energy and mineral wealth will solve Earth’s resource shortages.” Both comments are from the founder of the Ansari X Prize.

Many people, including myself, are worried that this sort of attitude is going to lead to a disregard for environmental concerns, and reinforce the “throw away” attitude that many people currently have. “Who cares about recycling, if we can get all we need from the solar system?” Ultimately though, if we take that tack, we’re going to run out of resources, even if it takes a thousand years, or pollute the other planets like we’re doing to Earth.

Fortunately, not everyone thinks like this. Some want to put into place a system of conservation parks on Mars, to protect the most important sites like Olympus Mons, the largest volcano (mainly form irresponsible mountineers from despoiling like has happened to Mount Everest!), the ice caps for biological studies, and the landing sites of earlier space craft. Th

However, there’s still no agreed property laws in space. One can hope that we will come to an agreement like in Antarctica, but as the U.S., Russia and China haven’t event signed onto the existing UN Moon Treaty (to make the Moon and other celestial bodies “the province of all mankind”) it’s easy to be concerned.

Ultimately, we need a compromise. Commercial enterprise is a fact of life, but I think we have to start building conservation, scientific research and heritage sites into the business models from the ground up, rather than as weak laws after the fact. Perhaps these new worlds will give us the chance to change the way we as a planet do business. (Sorry for another long post - it will give you some weekend reading!)

Slashdot is reporting a fabulous device for scientists who want to get back to nature - a digital sundial. And no, it’s not just solar power clock. It uses no electricity, and has no moving parts - just like a “real” sundial.

So how does it work? Using a clever series of slits cut in the screen, sunlight shines through one side and illuminates the shape of numbers on the other. As the sun moves, the beams of sunlight move across and light up different slits (squint your eyes on that image!) creating a new number but still in the same spot! It’s the same principles as some rulers, Tazos, etc that change their picture when you move them back and forwards. The clock works in 5 minute increments, with the numbers fading between each other, so it’s possible to interpolate a little to get better accuracy.

What I (as a physicist!) found most fascinating was how they compensated for the “non-linearity” of the movement of the sunbeams. You can see this by watching the length of a shadow during the day - it changes quickly in the morning and evening, but slowly at noon when the sun is overhead. The sun’s still moving at the same speed across the sky, but the angle the light beams make with a pole (such as a lamp post, or the stick on a normal sundial) changes most when the sun is low in the sky. Think about this - it does make sense!

Therefore, conventional sundials must compensate for this by spacing their hour marks further apart in the afternoon than in the middle of the day. But the digital sundial uses a much neater trick - it uses a layer of refractive medium such as glass or water to compensate. You’ve seen this effect when you look at a spoon in a glass of water - notice how the spoon appears bent? It’s because light from the spoon is being bent by the water. Most importantly, this effect becomes more pronounced when the angle gets shallower, but doesn’t do anything when you’re directly above the water - so we can use it to compensate as the sun gets lower and lower in the sky but not do anything when it’s overhead! Brilliant!

And, best of all, if my earlier suggestions didn’t find you that perfect gift for Christmas, you can pick a tabletop version up for about US$100.

I posted earlier about New Scientist’s list of the best science gifts. Now Wired News has a list of its own, with gifts ranging from $5 to $1500 and for ages 5 to 500 (Actually I just made that last bit up. But it’s true in theory!)

High on my list is the Brain Gelatin Mould (available in Australia from the Medical book centre, either online or in Milton, QLD), hand boilers, which contain liquids that boil at the temperature of your hand. (Possibly problematic in Brisbane, Australia where the temperature has been reaching mid thirties recently, and set to go higher…) And for that love of your life who has stars in their eyes, why not get a Meteorite Pendant, and put (ex-)stars around their neck as well?

So I’m sponging off a couple of other blogs at the moment, but Uncertain Principles found a great Trebuchet simulator where you get to play with a medieval catapult and vary its properties to get the best effect. Great fun, and I learned (or relearned!) at least a couple of unintuitive things! (What does gravity do the projectile’s path?)

Preposterous Universe quoted a fabulous story from the American Astronomical Society newsletter by Robert Kirshner, the President. Despite possible lawsuits, here it is:

Everybody has this happen to them — you’re sitting on an airplane, headed for the AAS meeting or an observing run or a windowless room at NASA headquarters when a stranger sits down in the seat next to you. You’re revising a manuscript (changing “affect” to “effect” or the other way around), or writing a referee report (”this paper contains too few references to the pioneering work of the anonymous referee”), or browsing through the AJ (”this paper is pretty good, I wonder if I’m a co-author.”) The person next to you, picking up on these subtle cues, asks, “What do you do?” Here you must make a quick judgment. Do you want to talk to this person?

If your answer is yes, then you say, “I’m an astronomer” and you can be sure your neighbor will pick up that thread — possibly asking for a personal horoscope, possibly asking you for insider information on that satellite that landed so firmly in Utah, and possibly asking if the dark energy is really the cosmological constant. In any case, both time and the airplane will fly.

On the other hand, if the idea of talking to this stranger (”outreach” in NSF-speak) is less appealing than having three hours of root canal work, you just say, “I’m a physicist.” Somehow, that always produces a social retreat, leaving you in your own cocoon of noise-cancellation to compose letters of recommendation that skirt the inside edge of perjury.

If you don’t study/do physics you’ve probably never experienced it, and as a reader of this blog you’re unlikely to perpetrate it, but believe you me - it is a completely real scenario. At our University’s “Market Day” the Physics Society PAIN puts on shows and displays and people are fascinated until you mention you’re a physics club. Then they run away as fast as they can. Whereas if there’s a telescope to look through, people will come from miles around. Guess we’ve just got to keep working at it!

I wrote a piece last week about “cyborgs” and brain-computer interfaces. I thought I’d just post a couple of relevant updates. Unbeknownst to me at the time (should have done more research!) BrainGate, the chip which is implanted in the brain and used to read neural signals, has been used in a
human trial and has been highly successful:

[Using the BrainGate system] a 25 year old quadriplegic has successfully been able to switch on lights, adjust the volume on a TV, change channels and read e-mail using only his brain. Crucially, the patient was able to do these tasks while carrying on a conversation and moving his head at the same time.

The patient, Matthew Nagle (according to that article - he’s not named in the others) was a “former football star” who was paralysed when a stabbing attack severed his spinal cord (though one has to wonder at exactly how they define “football star” - not that I mean to detract from him in any way, it’s just that that sort of thing makes for a good news story.) He trains each day to hone his control.

Despite somewhat misleading media statements like “[he] thinks about opening his email, and it happens”, just remember that there’s nothing spooky about this. You think about moving your arm, and it happens. You think about reading these words, and you’ve not only followed them with your eyes and read them, but you’ve processed them, understood them and remembered them. The brain is an amazing thing, and all they’re doing is giving the brain access to other “limbs” (e.g., a light switch) and letting it learn how to control it, something the brain is excellent at.

All the same, it brings cybernetics closer to reality. My friend, Brett, has some interesting thoughts about the future of human-machine hybrids, and what sort of modifications are “acceptable”. It’s interesting that the idea of elite “superhumans” comes up again, just as it does in genetic engineering, and the implications it would have on society. I would strongly recommend watching Gattaca for views on the latter (though whether you think it is a likely future is up to you - I’m not convinced, but I think the United States particularly could start leaning that way all too easily.)

Another must-read is Asimov’s Robot Novels (starting with Caves of Steel). In particular, he has a population (the Solarans) who become more and more attached to their robots and computers (building brain-computer interfaces, etc) to the point of thinking themselves superior to the rest of the galaxy, and shunning all human contact, even amongst themselves. This is extreme compared to the rest of Asimov’s populated worlds, but is it unbelievable? Like much of Asimov’s work, we should at least think about it.