illuminating science

I’ve (quite unintentionally!) been conducting an interesting (mostly social!) experiment in my local park. On Sunday, a friend of mine was to have a staff meeting in the park across the road from my house (for Domino’s Pizza - in full uniform no less!) They weren’t paid for the meeting, and she wasn’t particularly looking forward to going out in public in the charming costumes they wear (hehe!) so to try and liven up her afternoon, I decided I’d plant balloon animals around the park where I assumed the meeting would be.

In fact, the meeting was cancelled, and while we got the chance to admire my balloon creations in situ, they didn’t receive the fame and glory they deserved - at first! Five animals took up residence - a giraffe, a horse, a poodle, a flower and a parrot in the tree. That afternoon, while we watched, someone came by and started photographing all the different animals, which was quite cool. The next day, the giraffe had come loose and popped. The day after (yesterday) the flower was gone - apparently picked by someone, rather than just popped or blown away (perhaps a young lover attempting to impress his (her!) beau?) At last count, this morning that is, the horse was also gone - possibly blown away, but it seems more likely again plucked from its hidy hole. Interestingly, the pink poodle, the most popular balloon for children (alright, girls anyway), still remains!

What does this have to do with physics? Not much - except that it seems that balloon animals in a park exhibit a linear decay rate - so far, I’ve lost one per day - which is quite unusual in physical systems. On the other hand, I’ve only seen a change of 60% (from 5 to 2!), with only 3 data points, so it’s quite possible that it really is an exponential fit (the usual decaying then flattening off graph you often see) with some error bars. Regardless, I think there’s enough interesting statistics to warrant applying for a larger grant for a mass deployment of balloon animals throughout Brisbane each with electronic tags to track their movements. If I can just tap into the government’s secret database of personal info, I’ll also have a complete dossier on who steals balloon flowers too!

Physics papers are often completely obtuse, with helpful statements like “It should be intuitively obvious that…” or “It can be understood that…” when in fact the point in question is neither obvious to nor understood by anyone except for the author, and perhaps the author’s colleagues. Perhaps. Oh, okay, I’m exagerating - but certainly to a non-expert in the field, cryptic passages are too often the norm, and you wonder if they’re actually speaking another language.

But I’ve never seen a paper where this is quite so apt as E. Joos, Continuous measurement: Watchdog effect versus golden rule Phys. Rev. D 29, 1626–1633 (1984), which features this fantastic passage:

A master equation int he context of quantum mechanics was first derived by Pauli. […] this may find its justification in the interaction with the environment. Pauli’s work also contains some remarks which may be understood in this way:

“… um dagegen den zeitlichen Ablauf irgendeines Vorganges zu erfassen, muss ein System stets als durch irgendwelche Apparate messend verfolgt, d.h. als unabgeschlossen angesehen werden.” “… werden im allgemienen die Beobachtungen selbst eine solche Regellosigkeit begunstigen.”

In view of the previous section…

“Understood in this way”?! Now if I just knew whether this was a deliberate joke or not!

So there are two interesting talks (or good sounding talks, anyway!) coming in Brisbane in the next week. The first is on Friday this week, and is as much a philosophy talk as anything else:

The Matrix as Metaphysics

Are we living in a Matrix? And if so, is our perception of the external world illusory? Many people, including philosophers from Descartes to Morpheus, say yes: if we’re in a Matrix, then the ordinary objects that we seem to see don’t exist, and we’re radically deluded. I say no: even if we’re in a Matrix, ordinary objects still exist, and most of our beliefs about the external world are correct. Instead, we can see the Matrix hypothesis as a metaphysical hypothesis about the underlying nature of our world: one according to which the physics of our world is computational.

The speaker is Prof. David Chalmers from ANU, and the one hour talk starts at 4pm, after which there’s going to be a discussion for an hour, followed by food! It sounds ever so slightly wacky, but it will probably spark lots of interesting discussion, so great! I don’t know exactly what will be discussed, or on what level - guess we’ll just have to wait and see! There was an article some time back that purported to prove that either the Universe was finite (or was it infinite?) or we live in a (the) Matrix - I can’t find the reference now and never read it at the time, so that’s all I’ve got.

The other talk is the BrisScience series on Monday featuring Brian Schmidt, also from ANU, about the past, present and future of our Universe. Unfortunately, I’m not able to make it, but it should be an excellent talk for anyone interested in astronomy and cosmology! It starts at 6:30pm and features wine and nibblies afterwards! (Not that, as a grad student, free food is my only thought!)

A good week for expanding your physics brain!

Update: BrettW has pointed out a summary of the talk on Prof. Chalmers’ website. Well worth a bit of prereading, I think! I have thoughts already, but I’ll hold off until the talk and discussion

I know I shouldn’t do this, but…Someone’s been sort-of spamming my blog with revelations that they have uncovered the fundamental laws of the universe - the theory proudly titled graviomagnetism. This site is quite wacky, and although not as crazy as many crackpot sites is clearly written by someone who hasn’t properly researched current theories of general relativity, gravity and electromagnetism. Note that that’s not to say those theories are right, but a pretty strong requirement of any new model would be to fit into these existing theories (that have yet to be proved wrong) or, alternatively, show how these theories fit into some new, larger theory. In particular, his section on black holes is incredibly simplistic:

In a black hole matter is compressed in a very small volume, the particles have very small volume in which to vibrate, the temperature is a measure of particles agitation, it implies that the temperature is near to 0 Kelvin because particles have very small space for agitation, there is hardly no thermal radiation, the radiation is minuscule (Hawking radiation), when a photon falls on the black hole the reflection is minuscule because the particles are in a very confined space, they can hardly vibrate to reemit light, the photon is converted to masse. That is why black holes are black.

Not to say that’s not an attractive explanation, but it just doesn’t hold water. Particles can be compressed into a very small volume (like “electron degnerate” or “neutron degenerate” matter, where electrons or neutrons are packed as closely as they can physically go) and still be incredibly hot. Neutron stars (neutron degenerate matter) are an excellent example of this which we’re pretty certain exist). This is kind of like the explanation I had for paper when I was 4 years old - I knew it was made out of wood, so I thought they just took trees and sliced them up very thinly! I even have the illustrated “textbook” that I wrote explaining the whole process

Anyway, if you’re bored, have a read - the introduction with lots of name dropping is particularly entertaining (okay, I’m being horrible, I know!) But my favourite comment is the unfortunate typo before he starts onto black holes: “Before getting a head…”

Really interesting article on Digg today, about how one can mark nuclear waste storage facilities as dangerous for as long as it will take the waste to decay - we’re talking 10,000 years into the future. Who knows what sort of language, culture or environment will exist? What sort of environmental conditions there will be, whether civilisations will exist as they are now, or even whether humans will even exist in their current form?

A few interesting ideas came out of the panel - I won’t cover everything here as the article is a good read already, but I’ll mention a couple. One was whether you should even mark the site at all - having any sort of monuments or markers might actually encourage future archaeologists to explore the site. Perhaps it would be better to remove all trace that anything was there, so that no-one would think to look at this obscure spot out in the desert. In the end they decided against this, and for my two cents, I definitely agree. Security through obfuscation is always a bad idea (e.g., having a secret way into your house that is never locked, just no-one knows about - it’s fine while it’s hidden, but if someone stumbles upon it, it’s all bad).

Instead, they explored options such as having a jagged landscape of thorny spikes rising up out of the ground, pointing in all different directions. The hope would be that this would inspire a sense of forboding and/or fear in people, and make them at least be cautious about exploring. Another option was large black blocks which would heat up in the desert sun and make travelling the area very uncomfortable. In the end, cost was the deciding factor, and the final design consists of “earthen berms”, basically large jagged dirt/rock formations all around the area, again inspiring a sense of forboding. Then, detailed information will be stored, buried or engraved in all the languages of the United Nations, including astronomical charts and wood for possible carbon dating, so that future societies could determine when the waste was buried.

In many ways, it’s similar to the creation of a plaque to go onto space ships, although with slightly different challenges. Here, at least, there’s some common ground (we expect they’ll still be humans, as opposed to aliens) but here we’re trying to communicate a specific message to a culture that may or may not have any idea about nuclear waste.

I wonder, however, if the simplest thing might not to engrave or in some other way place permanent photos of corpses, people suffering from radiation sickness, etc, around the site. In terms of communicating danger, this is a pretty effective way of doing it, and one which should be pretty obvious to any human. There are probably ethical issues there, though.

The only other thing that I wondered about was whether any of this would do any good. We open Egyptian tombs with no regards for any of the “decorations” that were (presumably) meant to forbid entry. Humans have a habit of being curious, despite any risks, which I honestly thing is a good thing. But perhaps at the end of the day, if people do go down to explore and die from exposure, the culture is going to quickly indentify this as a forbidden place and it will become forbidden once more, at least for their lifetime.

Okay, not quite, but a group of US Universities funded by DARPA (the U.S. Defense Advanced Research Projects Agency) has created a robotic tentacle that might one day be used to create, among other things, a backpack with extra arms! It’s Doc Ock come to life! Admittedly, the arms probably won’t have true artificial intelligence. And admittedly, they’ll probably use something a little more secure than just an external chip clipped to the back on the subject’s neck to prevent that.

More practically speaking, it’s hoped that these new robotic arms, which actually seem a lot more like an elephant’s trunk than an octopus’ limb, will be useful for sensitive work such as bomb disposal, remotely searching for survivers of disasters, or other sensitive work that can’t be done safely by humans. They really are a pretty remarkably feat of engineering - check out their website, which includes some great videos, especially the one where the arm steals and defends its prize - a can of Coke!

Ever heard of ferrohydrodynamics? Nope, neither had I. From the name, it suggests something to do with metal or magnets (”ferro”), something to do with water (”hydro”) and some sort of resulting motion (”dynamics”) but words can’t really capture just how cool ferrohydrodynamics really is (not to mention the fact that it’s hard to say!)

In fact, ferrohydrodynamics describes is the motion of ferrofluids - liquids which respond to magnetic fields - when you apply strong and varying magnetic fields to them. In the ideal case, these fluids will remain as, er, fluids even when you apply very strong magnetic fields. Related are “magnetorheological fluids” which tend to solidy when you apply a strong enough magnetic field (I think due to clumping of the magnetic particles). A simple magnetorheological fluid can be made at home by mixing some magnetic particles into vegetable oil - apparently, using iron extracted from sand by a magnet makes a really good fluid, that will harden when a large magnetic is placed nearby.

To see these fluids in action, check out the utterly amazing movie from MIT of a high quality ferrofluid (one that won’t solidy) under the influence of rotating and opposing magnetic fields. They’ve created some amazing shapes that are really fascinating to watch as they evolve and change - it’s hard to believe it’s simply the result of a straight magnetic field! The actual description below the movie is beyond me, but it’s still neat to watch