Science is Golden

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Science is Golden Page 16

by Karl Kruszelnicki


  Are the natural opiates endorphins? Probably. Mind you, it was a very small sample size.

  So, in this case, the claim that brain opiates cause the Runner’s High is probably true. But it took us one-third of a century to prove it.

  References

  Boecker, H., et al., ‘The Runner’s High: Opiodergic mechanisms in the human brain’, Cerebral Cortex, 21 February 2008.

  Hughes, J., et al., ‘Identification of two related pentapeptides from the brain, with potent opiate agonist activity’, Nature, 18 December 1975, pp 577–579.

  Kolata, Gina, ‘Yes, running can make you high’, The New York Times, 27 March 2008.

  Simantov, R., et al., ‘Morphine-like peptides in mammalian brain: Isolation, structure elucidation, and interactions with the opiate receptor’, Proceedings of the National Academy of Sciences, July 1976, Vol 73, Issue 7, pp 2515–2519.

  Is This On, Mike?

  I do a bit of speaking at universities, conferences and public meetings and have come to know the audiovisual (AV) people quite well. They have told me how a few common mythconceptions about microphones make their job hard.

  There are two myths. One, the way to test a microphone is to tap it firmly with the fingers. Two, microphones will magically ‘reach out’ and amplify only the speaker’s voice, no matter how quietly they speak.

  Microphone 101

  The word ‘microphone’ comes from the Greek words mikros meaning ‘small’ and phone meaning ‘voice’ or ‘sound’.

  One of the first appearances of the word was in a 1683 dictionary, where it was defined as ‘an instrument by which small sounds are intensified’. Of course, this referred to non-electronic devices, such as megaphones and ear trumpets.

  The first ‘modern’ microphones appeared in the 1870s. In one early version, the person’s voice came in through a funnel, landing on a stretched membrane of thin metal, which then vibrated. This membrane was attached to a sharp needle, which scratched a pattern into thin metal foil. You could also run this system backwards. In this case, when the needle ran over the foil, the membrane vibrated, allowing you to hear a rough version of the original sound.

  Today, most microphones rely on the speaker’s voice setting off pressure waves in the air, which then land on a diaphragm. In the popular dynamic microphone (which often looks like an ice-cream cone), the diaphragm is attached to a ring-shaped coil of thin wires. The coil is either inside a hollow magnet or has a magnet inside it. Either way, when the diaphragm moves relative to the magnet, electricity flows through the wires of the coil. This electricity is then amplified and pumped out through the loudspeakers.

  Public Speaking 101

  The human brain is highly proficient at listening to a specific source in a noisy environment. It can filter out all the unwanted noise and bring into the foreground the sounds that you are concentrating on, such as another person’s conversation in a crowded room.

  However, our current technology—the combination of a microphone and an amplifier—has not yet been able to do this. Today’s mike and amp will make everything louder—both the unwanted background noise and the signal that you want.

  If you speak softly into the microphone (which is what most people do), the mike technician has to crank up the volume on the amplifier. Although this will make your voice loud enough for the audience to hear, unfortunately it will also make the background noise louder. The audience will notice this unwanted, amplified noise.

  But if you speak more loudly, the mike technician can reduce the overall volume. With the amplifier turned down the background noise will be reduced. But the audience will still hear you clearly, because you are speaking more loudly.

  Testing…One, Two, Three

  The word ‘microphone’ comes from the Greek language—‘micros’ means small, and ‘phone’ means voice.

  Microphones convert acoustical energy (sound waves) into electrical energy (the audio signal).

  Cross-section of a dynamic mike

  Mike Myths

  The first of the two myths claims that the way to test whether a microphone is working is to tap it firmly.

  Unfortunately, the diaphragm inside a mike is delicate. It is designed to move in response to tiny variations in air pressure. Therefore, a solid thump can sometimes knock the delicate internal mechanisms out of place. At the very least, you will inject a sharp audio ‘spike’ through the entire audio chain from the microphone to the amplifier and the loudspeakers. This ‘spike’ has been known to cause damage.

  The microphone is a device that is supposed to help amplify speech—its only function. So why not test this function by simply speaking into it? AV technicians often tell me that they are bemused as to why a speaker thinks that the only way to test a mike is to hit it firmly.

  The second myth claims that you do not have to speak loudly into a microphone.

  People believe that the mike will somehow magically ‘reach out’ and amplify only their voice. So widespread is this belief that most people will actually speak more softly than normal into a mike.

  And when they hear their own amplified voice coming through the loudspeakers, they do not see this as a sign of success—which it is. Instead, they will deliberately speak more softly and/or move their mouth away from the mike, until they can no longer hear themselves.

  The AV technicians at the back of the hall are now left with only one option—to increase the amplification of the microphone circuit. The microphone will now pick up the faint mouse-like whimperings of the speaker—as well as the speaker’s own voice coming through the loudspeakers. This can then set off the squeal of the dreaded ‘feedback loop’. In response, most speakers will talk even more quietly. And the AV technicians at the back of the hall get even more annoyed, because the audience now blames them and not the poor microphone technique of the speaker, for the bad sound.

  My Mike Technique

  I usually use a lapel mike (in my shirt). This leaves my hands free to operate the laser pointer and the remote control for the presentation. If I were to turn my head to one side or the other, I would go ‘off mike’, so I am careful to turn my head and shoulders as one unit.

  I always ask for a new battery (even so, I have had a battery die on me a few times, when the technicians have told me that a new battery has been installed, but wasn’t). I am a stage walker (i.e. I don’t stand still at a lectern). So before a presentation I walk around the stage to see if there are locations to avoid because of possible feedback. I also test the mike by speaking at the loudest and softest levels I will use on stage, so that the technicians can set the levels correctly. And, of course, I always run the cable inside my shirt—for a more professional look.

  The Cure

  I have been present at practice sessions when the AV technicians have come onto the stage and asked the presenter to speak more loudly. The presenter then continues to speak at exactly the same volume. For some unknown reason, they seem to have a real reluctance to speaking loudly. But this is exactly what actors do on stage—they ‘project’ their voices. I saw one technician use a neat trick to get the presenter to speak more loudly. She would say, ‘Imagine that your child is drowning in a river, and that you want to call for help. Now start calling for help.’ In many cases, this simple exercise would open the floodgates, the presenter then beginning to speak more loudly.

  So next time you’re on stage, get close to the microphone, don’t tap it, speak loudly—and the only feedback you’ll get will be applause.

  Roadie for Bo Diddley

  I spent a few years as a roadie for a few bands in Sydney. This involved loading the speakers and amps into the van, setting them up at the gig, wiring it all up, and then ‘bumping out’ at the end of the gig. One of these bands, Wasted Daze, was invited to be the backing band for Bo Diddley (the blues musician) for two of his Australian tours.

  So that’s how I became a roadie for Bo.

  Reference

  Nisbett, Alec, The Use of Microphones, Lon
don: Focal Press, 1983.

  Crash Collider: LHC Destroys Universe

  Back in the Old Days, before terrorists and tsunamis were blamed for trying to destroy the Earth, it was the labcoat-wearing, mostly bald (apart from two tufts of hair), certifiably mad and totally friendless Mad Scientists who were going to do it with one of their crazy experiments. No surprise, but scientists are back in the firing line.

  Terrifyingly, this time scientists are being accused of trying to blow up the Universe. The firing up of the Large Hadron Collider (LHC) in Europe has also fired up a groundswell of paranoia against this science experiment that will supposedly unleash uncontrollable forces, wreck the planet and kill us all—and a few moments later, destroy the entire Universe as well.

  There are three specific doomsday claims—that the wacky scientists will accidentally make a Black Hole that will swallow the Earth, or that they will collapse the Universe into a weird quantum vacuum, or that they will convert all the matter in the Universe into ‘strange’ matter.

  But what is the LHC and why are the doomsayers wrong?

  What is the LHC?

  The Large Hadron Collider (LHC) was built to help answer some Big Questions in Particle Physics. It has taken over 20 years, and scientists and engineers from over 60 countries, to build, and is designed to recreate some of the titanic energies found in the Universe immediately after the Big Bang.

  The largest and most powerful collider ever built, it is located inside a huge, specially constructed underground tunnel, shaped like a ring, which straddles the borders of Switzerland and France.

  The LHC will generate so much raw data that if it were stored on CDs, the stack would reach the Moon in six months. The project will employ about half of all the particle physicists in the world.

  Particle Physics 101

  It has been said that Particle Physics is like throwing two watches at each other at high speed, and then trying to work out how a watch works by looking at the various bits that come flying out. Trying to understand what everything is made of has bothered thinkers and scientists for thousands of years.

  In 1915, Ernest Rutherford, the New Zealand-born scientist, fired charged helium atoms (alpha particles) at a sheet of very thin gold foil. The thinking at the time was that matter was made from large solid atoms, so matter was like large solid plums (the atoms) richly scattered through a pudding (the stuff in between). Rutherford expected the helium atoms to go through the foil, and that they would all be slightly deflected at a small angle, as they hit the atoms in the foil. Instead, most of the alpha particles went straight through the foil, totally unaffected—but were deflected at more than 90°. He later said: ‘It was almost as incredible as if you fired a fifteen-inch [38 cm] shell at a piece of tissue paper and it came back and hit you.’

  He had discovered that atoms were mostly empty space, with tiny solid cores. The atom is kind of like a tiny solar system, with the nucleus at the centre and electrons orbiting around it.

  Then it was discovered that the nucleus itself is made of protons and neutrons.

  Then it was discovered that the protons and neutrons were made from `quarks’ and gluons. And now we have the Large Hadron Collider…

  What LHC Does

  The LHC collides together two beams of protons, i.e. hadrons, that are travelling in opposite directions. ‘Hadrons’ are subatomic particles (such as the protons or neutrons in the core of an atom) that interact with each other strongly.

  The 300 trillion protons in each beam travel at 99.99991% of the speed of light through skinny pipes just 5 cm in diameter. These tiny pipes are inside cylinders full of wiring, electronics and magnets. The cylinders are arranged in a circle 27 km in circumference, and are buried 50–100 m underground. At that speed, all of the speeding protons put together have the energy of an express train.

  The protons orbit the ring about 11,000 times each second. The protons would travel in a straight line, except for the 1,200 superpowerful magnets which force them to take a curved path. These are not ordinary magnets—they each weigh several tonnes, and make up the largest array of superconducting magnets ever built. To keep the magnets in the superconducting mode, they are cooled by 130 tonnes of liquid helium. The liquid helium is colder than the temperature of deep Space.

  This kind of high-energy physics can be hazardous. If a loose nut or screw is left lying around when one of these magnets is switched on, it will smash into the magnet with the speed of a bullet and destroy it. On the other hand, if any of the magnets fail, the proton beam will stop following the curve of the pipes and burn through the pipe wall. The energy in the beam is the same as in 157 kg of TNT—you wouldn’t want to be near the beam if it punched its way out of its tiny pipe! The energy stored in the magnets is even greater—the same as in 2.5 tonnes of TNT.

  Once the beam has been switched on, it runs for ten hours before needing to be topped up. In that time, the protons cover a distance equal to a round trip to the planet Neptune and back.

  For most of the tunnel, the two proton beams are kept parallel and separate. But there are four crossing points where the beams hit each other. This is where the collisions happen—some 600 million of them each second. If any human beings were near the crossing points when the proton beams were running, they would die very quickly from the radiation.

  Large = Enormous

  The LHC has four main collision detectors. Over 2,500 scientists laboured to build just one of its four detectors—which, by itself, has more iron in it than the Eiffel Tower.

  These ‘detectors’ aren’t small devices sitting on a benchtop, like those used in the early days of Particle Physics. Each one is about the size of a multi-storey building, wrapped around the collision zone, and costing up to several hundred million dollars.

  Catch the Fireball

  One of the detectors, called LHCb, is run by about 663 scientists. It has a fairly specific goal—to study the subtle differences between matter and antimatter. When the Universe popped into existence with the Big Bang, it had equal amounts of both. But now the Universe is made just of matter. Why? How? LHCb might help us answer these questions.

  Another detector, ALICE, also has a quite specific goal. It studies the quark-gluon plasma, by smashing together the nuclei of lead atoms.

  The other two detectors, ATLAS and CMS are more general. They catch and measure everything coming out of the collisions.

  There are four separate detectors, so there are four collision zones or crossing points. The detectors have been built by separate teams, and work both independently of each other, and together.

  The collisions at these crossing points produce a primordial fireball, which then cools down into various subatomic particles, which then are caught by the detectors. Hopefully, the products of the collisions will include the long-sought Higgs Particle, which is thought to endow everything in the Universe with the strange property that we call ‘mass’.

  When Science or Technology is very advanced, it becomes Art. One of the theorists at the European Organization for Nuclear Research (known as CERN) calls these detectors ‘sunken cathedrals’.

  The (Really) Large Hadron Collider

  Location: Border of France and Switzerland LHC

  Circumference: 27.5 kilometres approx.

  The countryside near Geneva is home to the world’s most massive physics experiment.

  Inside the LHC, insanely big and powerful magnets that have been chilled to a few degrees above absolute zero, will shoot beams of superenergetic protons and lead nuclei in a loop at incredibly high speeds. The speeds reached are close to the speed of light and when the protons collide head-on they will replicate conditions that existed mere moments after the Big Bang.

  ATLAS vs CMS

  ATLAS weighs 7,000 tonnes, and is run by 1,800 scientists from 34 countries. It is both larger and lighter than CMS—so light that if you wrapped it in plastic sheeting, it would float on water. It’s about 45 m long and 25 m high, and would half fill the Cathedr
al of Notre Dame in Paris.

  CMS stands for Compact Muon Solenoid—but obviously the scientists were having a little joke when they called it ‘compact’. It weighs 12,500 tonnes, and is 15 m high and 23 m long. It takes about 2,500 scientists from 37 countries and 155 scientific institutions to run it. This is the one that has more iron in it than the Eiffel Tower. At the very heart of the CMS is a camera that photographs the particles erupting out from the primeval fireball—but what a camera! It has a 60 megapixel chip, and can take 40 million pictures each second (that’s right, not 40 but 40 million).

  The Higgs Particle

  You’ve probably heard that mass and energy can be turned into each other. In a nuclear weapon, a small amount of mass is turned into a huge amount of energy. In the collisions in the LHC, the opposite happens—energy is turned into mass. In a bizarre example of how mass and energy can be interchanged, two small, fast-moving protons will collide to make much heavier slower particles—like two nippy light planes colliding to make a lumbering bus. The energy of the speeding protons will hopefully be converted to the mass of the Higgs Particle—the Holy Grail of Particle Physics. It is supposed to endow ‘stuff’ with this weird property called ‘mass’.

 

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