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The fantastic accomplishment of the Curiosity probe landing on mars has once again turned the world’s eyes towards the heavens (if we forget about the Olympics for a moment of course). Using this recent feat of human ingenuity and resourcefulness and a recent trip to the Kennedy space centre for inspiration I’ve decided to write a short piece on the history of human exploration in space, with a post soon to follow about the Curiosity probe, I hope!

Exactly 70 years ago, Wernher von Braun watched on as his brainchild, the V-2 sub-orbital ballistic missile, became the first man-made object in human history to leave the atmosphere and enter, by today’s standards, outer space. In the words of Walter Dornberger, the head of the V-2 rocket programme

“This third day of October, 1942, is the first of a new era in transportation that of space travel…”

Three years later, 1945, at the onset of operation Paperclip and operation Backfire, the American and British scramble for Nazi weaponry and technology, hundreds of V-2 rockets were secretly shipped back to the US, along with some of the Third Reich’s most able minds. For nearly a decade after this, nothing happened, there was little advancement on the German designs and schemes as both western and eastern scientists struggled to come to grips with the sheer complexity and intricacy of the Nazi engineering, but that was soon to change

While the Americans and British were messing with rockets little more advanced than large fireworks, with the fantastic German scientists side-lined for matters of national pride, something interesting had been happening on the far side of the iron curtain…

Using some of this stolen Nazi tech, the Russian space programme, after languishing behind the rest of the world for several years, suddenly kicked into high gear. For years the Soviet cosmodromes had been churning out successful rockets in the forms of the R-1, R-2, R-5 and R-7 families, but here the Russians hit a stumbling block, where do they go from here? The Americans provided them the perfect answer. On 29th July 1955 the U.S. President Dwight D. Eisenhower announced that the United States would launch an artificial satellite during the International Geophysical Year of 1957. Terrified that the Americans would use this satellite as a spy satellite, or worse, the Russians rushed into action, planning, designing and building a fully functioning satellite in just over two years, and on the 4th October 1957 they launched the world’s first satellite into low earth orbit, Sputnik 1. The space race had begun.

Apollo 11 launches from pad 39 A

Skip forward 10 years, to 1967, and Von Braun’s greatest achievement sits atop a launch pad, aimed for the sky, the Saturn V rocket. Even to this day the Saturn V holds several records, for being the tallest, most powerful and the heaviest rocket ever produced. For several years the Americans had trailed behind the Russians in the great space race, relying on reverse engineered technology for their flawed and unreliable Vanguard class rockets, but after the Soviet success of Sputnik the Americans panicked and at the orders of the government, placed Von Braun and his team in direct command of rocket design for the Americans. Almost instantly the American space programme began to pick up speed, and with the declaration in 1961 by John F. Kennedy of the national goal of “landing a man on the Moon and returning him safely to the Earth” there seemed like there could be no stopping the Apollo space programme, the Americans method of placing a man on the moon. Even with its fantastic and, at the time, outlandish goals Apollo succeeded despite the major setback of a 1967 Apollo 1 cabin fire that killed the entire crew during a pre-launch test. Six manned landings on the Moon were achieved. A seventh landing mission, the 1970 Apollo 13 flight, failed in transit to the Moon when an oxygen tank explosion disabled the command spacecraft’s propulsion and life support, forcing the crew to use the Lunar Module as a “lifeboat” for these functions to return to Earth safely. But despite all of this, at Apollo’s discontinuation, NASA declared the programme as “a success”.

This success of landing a man on the moon signalled the end of the space race between the US and Soviet Russia, but it was by no means the end.

The next major breakthrough was Salyut 1, the world’s first space station. Beaten to the moon by the Americans, Russia began to concentrate its resources on sustaining a manned low earth orbit. Although this goal wasn’t achieved truly successfully until Salyut 3 (Salyut 1 was left to fall out of orbit after one crew couldn’t dock successfully and another died on re-entry, Salyut 2’s flight control system failed and an unexplained incident where four solar panels were torn off the craft meant the station was left without power or a way of controlling it, this was again left to re-enter and disintegrate). Salyut 3’s main purpose was as a spy satellite and as a result It tested a wide variety of reconnaissance sensors, returning a canister of film for analysis. On January 24, 1975, after the station had been ordered to deorbit, trials of the on-board 23 mm anti-satellite cannon were conducted with positive results at ranges from 3000 m to 500 m, the departing crew reported that a target satellite had been successfully destroyed.

The latest hurdle crossed in space station building has been with the ISS (international space station), an international collaboration of five space agency’s: the American NASA, the Russian Federal Space Agency, the Japanese JAXA, the European ESA, and the Canadian CSA.

While all of this continues in low earth orbit, countless satellites and probes have been sent deep into the solar system. Some of the most famous ones being the Viking probes of mars, the first man-made objects to successfully land on the red planet and the Voyager probes, currently the furthest man-made objects ever (voyager 1 has recently entered the heliosheath and is predicted to enter interstellar space sometime around 2015). And recently there’s a new one to add to this very exclusive list, the Curiosity Mars probe, the largest and most advanced probe to ever land on another planet. The size of a small car and powered by a nuclear reactor, the Curiosity probe hopes to give us new insights into the history of mars, and whether there has ever been life on the red planet. It plans to do this by incinerating rocks with an on-board laser and analysing the gas given off to detect organic particles and elements and molecules that could support life.

Now we’ve had the most recent, and now we move onto the future. The future of space exploration is a tricky beast to wrestle with, as no one’s quite sure what’s coming. No-one could have predicted the sheer speed at which we progressed from Wernher von Braun’s V-2 rocket, only seventy years ago; after all, we’re now planning manned missions to mars! But there is one group of people who’ve had a go. Project Daedalus was a study conducted between 1973 and 1978 by the British Interplanetary Society, the oldest society of its type, to design a plausible unmanned interstellar spacecraft. Intended mainly as a scientific probe, the design criteria specified that the spacecraft had to use current or near-future technology and had to be able to reach its destination within a human lifetime. The proposed design revolved around a hydrogen-3 pellet driven nuclear-pulse fusion rocket to accelerate to 12 per cent of the speed of light. Aimed at Barnard’s star the probe would carry 18 smaller micro-probes, with an aim to study the atmospheric configuration, the magnetic field strength, and to send back pictures of the star system and its planets, sending this data back to earth via the main probe, which would use its massive 40 metre engine bell as a communications antenna. However, due to its incredible speed, the probe would be unable to stop, hurtling on through space for the rest of its life.

And that’s that, a quick flyby tour of the human exploration of space and where we might be going with it. And to add I would love to have included everything in this article, from Yuri Gagarin and Laika the dog to the British Black Arrow project and America’s plans for a habitable mars base, but, alas, I have a word count to keep to, but if you really want, you could always look them up yourself?

Alex Davis

 

Webography

http://en.wikipedia.org/wiki/Voyager_1

http://en.wikipedia.org/wiki/British_Interplanetary_Society

http://en.wikipedia.org/wiki/Project_Daedalus

http://en.wikipedia.org/wiki/Salyut_program

http://www.bis-space.com/

http://www.nasa.gov/mission_pages/apollo/index.html

http://www.astronautix.com/project/salyut.htm

http://voyager.jpl.nasa.gov/

One Nasty Bacteria

Good news everyone!

 

Group A streptococcus is a bacterium that causes many illnesses from strep throat to scarlet fever. The Group A streptococcus bacterium is able to cause so many diseases and dodge the bodies immune responses because of certain factors. One is that it has M proteins on its surface, which give it acid and heat resistance, an advanced ability to attach to its host and resist phagocytosis (being engulfed by white blood cells). It is chemically similar to the body’s connective tissue meaning it can go unrecognized by the body thus avoiding phagocytosis. Another factor is that it can produce three types of exotoxins, such as streptokinase – a toxin that digests blood clots, allowing the bacteria to invade the body – allowing it to cause numerous diseases. One of the most shocking of the diseases it causes is Necrotising Fasciitis.

Necrotizing Fasciitis

If Group A streptococcus manages to pass through the throat lining or an opening in the skin then you have most probably contracted Necrotizing Fasciitis and practically zero chance of getting out unaffected. There are two types of Necrotizing Fasciitis:

  • Type 1 – polymicrobial; the infection consists of more than just one type of bacteria
  • Type 2 – monomicrobial; the infection consists of only one type of bacteria, this is the most common type of the disease

Group A streptococcus is only one of many bacteria that cause Necrotizing Fasciitis but is the main cause of type 2 infections.

At first you start off with minor symptoms that you would put down to either an allergy or a normal common flu, maybe inflammation/ irritation at the area of infection meaning it is easy for the doctor to misdiagnose the patient.

If your lucky the doctor will have heard of the disease and has a suspicion that you are infected, he will carry out several tests on factors such as your haemoglobin, liver proteins and white blood cell count. Once it has been confirmed that you are infected, the doctor will perform surgery and aggressively remove the infected tissue to stop the spreading, however it is likely you will be severely disfigured.

If you’re unlucky then you’ll carry on normally until it becomes too painful or you end up passing out and the doctor performs exploratory surgery and discover most of your tissue gone. You will not get out of this unchanged; disfigured or dead (to put it bluntly). It is sad to know that this disease only has around a 30% survival rate.

It’s noteworthy that the bacterium does not physically eat your tissue but releases exotoxins. One of the toxins known as a Superantigen causes some T-Cells to activate which in turn causes an overproduction of cytokines (proteins used for cell signaling) and possibly Toxic Shock Syndrome – a whole other thing on its own.

Do not fret however as it is unlikely that it will infect people with a generally healthy life style. 70% of cases occur in those with health problems such as diabetes, alcoholism and drug use. A way to make sure that you don’t get infected is to always clean cuts thoroughly.

So if you don’t have enough to worry about already such as work, paying the bills and having to listen to a Connor Maynard song then feel free to concern yourself with flesh eating bacteria.

Christian Tuckwell-Smith – Farnsworth

Sources:

Bill Bryson: A Short History of Nearly Everything

http://en.wikipedia.org/wiki/Necrotizing_fasciitis

http://www.nnff.org/nnff_factsheet.htm

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002415/

This week Harry’s been hard at work in the University of Hertfordshire, desperately searching for brown dwarf binaries and handling huge clumps of data in a room with no windows. He hasn’t seen sunlight in days, and is turning into some kind of astronomical mole-man. Will he find his pair of stars? Will he get to see sunlight? When did he start writing these little intros? Who is Keyser Soze? Read on to find out…

Monday-Tuesday (Attack of the Spreadsheets)

Who’d have thought that GCSE ICT would come in so handy? The past couple of days have presented me with such functional gems as “=AND(IF(BC4<3,1,0),IF(BF4<3,1,0),OR(AND(IF(BJ4>3,1,0),IF(BJ3>3,1,0)),AND(IF(BK4>3,1,0),IF(BK3>3,1,0))))”,
“=((F7+J7)/2)*(AV7/1000)*4.74” and the catchy little number “=10^((I6/5)+1)”.

Most of my days at the moment are spent on LibreOffice Calc, which is the Linux version of Excel. This means that it is free and it runs very smoothly, but occasionally the functions can go a little bit mad. I’m still having trouble trying to convince it that the cosine of 90° is 0, not 1.457849384E-17. So far I’m not doing very well, but hey-ho!

Wednesday-Thursday (Marvellous Magnitudes and Magical Moduli)

All this spreasheet manipulation hasn’t been in vain though, as we’re finally whittling down the list of candidate stars into something a bit more manageable. If last week was all about proper motion (and it was), then this week is all about colours, magnitudes and distance moduli. These things are essential for working out how far away from us a star actually is. After we’ve done this for a pair of stars, we can then calculate how far away they are from each other! Firstly, we have to consider the different “bands” that the star has been seen in. There are a great many bands of colour, through infra-red into visible and beyond, and these are labelled with letters from the alphabet, but not in alphabetical order (because scientists love to make things difficult). These bands are given as one letter minus another, for example “I-Z” or “J-H”. This is because the light is measured at a certain brightness in the J frequency, then a certain brightness in the H frequency. We can then see what the difference is to give us a band between these two frequencies. From these bands you can then find out the Absolute Magnitude of a star (this is the measurement of how bright a star would be if viewed from 10 parsecs* away, and allows us to have a well defined base value for the brightnesses of all stars) by matching the colour to a star of known magnitude on a chart. This was pretty laborious work, as I had over 200 separate entries, that I had to do twice (for reasons I will explain next week). As you can imagine, this took me a good day of estimating and eye-strain, but it was worth it in the end. Soon we had values for the maximum and minimum absolute magnitudes.

I then needed to get the Distance Modulus. This is a very important number that we use to work out the distance to a star. Luckily it’s really easy to work out! All you do is subtract the absolute magnitude from the apparent magnitude (how bright the star appears to be for us here on earth**), and viola! It’s then a simple matter of dividing it by five, adding one and putting 10 to the power of your new number. This gives you the distance to the star in parsecs, and since the scale is logarithmic (in powers of ten) a small difference in the modulus can make a very big difference in distance! Magnitudes are also logarithmic, so small differences there can make large differences later on. Basically, for such massive objects (stars and the like) you have to be ridiculously precise!

Once the distance has been worked out it takes some simple trigonometry (distance x angle of separation in arcseconds) to find out how far apart the stars are in real space! You can then begin to think about how likely it is that the stars are related, as the bigger the separation, the less likely they’re a pair. Often these objects are many thousands of Astronomical Units (distance from earth to the sun) apart, but some can still be linked together. It’s fantastic to think of two stars, so far apart, yet still whirling through the cosmos as a pair, inescapably linked by nothing more than the forces of gravity. Some of the distances are enough to make your head spin a little, though. In astronomy everything is (surprise-surprise) astronomically big!

It’s enough to make a chap want to take a siesta with a nice glass of Pimms, eh? Chin-chin!

Harry Saban – The Octave Doctor (Phd Pending)

*A parsec is an astronomical unit of distance measured using some clever trigonometry. As you should know, the earth goes round the sun, and this causes stars that are nearer to us to appear to move, relative to the stars that are very far away. This is called the stellar parallax and is used to work out parsecs and the difference is greatest every half a year, because the sun is on the opposite side of the “circle”. If a star appears to move one arcsecond in the sky, it is one parsec away. This means it forms a sort of triangle, with a baseline that is 2 AU wide, and a height of 1 parsec. Wikipedia has some good diagrams, if you’re finding this a bit tricky to visualise (it’s pretty odd).

**Or more precisely, from a satellite orbiting the earth. The brightness would be affected by the atmosphere down here on earth by all those pesky gas particles up there making mischief and generally having a whale of a time.

In school we are taught that there are two different kinds of chemical bonds that atoms can make; ionic bonds, where electrons from one atom are donated to another atoms, and covalent bonds, where electrons are shared between two atoms. The truth is that real chemical bonds are a mixture of both. When two atoms come together their atomic orbitals in the sub shells combine to form molecular orbitals. For every two atomic orbitals that collide, two molecular orbitals are created, one in a lower energy state than the other.

The lower energy state orbital is lower than either of the two original atomic orbitals and is known as the bonding orbital, by comparison the other molecular orbital is in a higher energy state than either of the atomic orbitals and is called the anti-bonding orbital. Where both orbitals have the same number of electrons in it, the difference between the anti-bonding orbital and the highest energy atomic orbital is greater than the difference between the bonding orbital and the lowest energy atomic orbital and so the bond wouldn’t form as both molecular orbitals would be in a higher energy state than the atomic orbitals from which it is formed. This is why atoms with full outer orbitals (the noble gases) don’t like to form molecular bonds here on earth. Maybe a diagram is in order:

The point of all this is that scientists in Norway have used computer simulations to model chemical bonds in the extreme magnetic fields of neutron stars and white dwarfs. They have found that a new type of chemical bond is formed at these extreme magnetic fields. The basis is that in these magnetic fields, the anti-bonding orbital can exist at a lower energy state than the highest energy atomic orbital. This means that the noble gases will be able to form new and interesting molecules of which the likes have never been seen on earth before. The only catch, and it’s a big one, is that the magnetic fields need to be in the region of 105 T which in much, much, much bigger than the measly 30-40T fields that we can muster here on earth at the minute. Ah well.

 

T. Gloess

Fun times with Space-Time

Good news everyone!

 

Einstein as we know was a brilliant man (but as it turns out not a outstanding student), producing E=mc2, the general and special theory of relativity and much more. I will be discussing one of his concepts – space-time.

 

Imagine a big trampoline in front of you. You place two bowling balls – one big and one small – on the trampoline apart from each other, you notice that the bowling balls make an indentation on the elastic surface; the bigger of the two balls causing a bigger indentation than the smaller. Now suppose you roll a tennis ball along the trampolines elastic surface, you’ll see that the path of the tennis ball is deflected by the indentations made by the bowling balls. In basics the trampoline’s surface represents space-time, the bowling balls represents stars or planets and the tennis ball – light.

 

You are probably exclaiming, “This is preposterous! We were told that light only travels in straight lines!” well for daily life this is true as the bending of light due to a house or that annoying child on his scooter is so small that it is unnoticeable, however on the scale of stars and such, it is quite a noticeable deflection. This analogy has some flaws such as forces that are acting on the tennis ball which would not affect light (friction and so fourth) but mainly that the trampoline gives the impression of space-time being flat whereas it is actually all around us. We can’t say that matter directly affects the path of light just that it affects space-time, which in turn affects light. From this it is reasonable to assume that light would have to slow down from being curved around a sun, but light is travelling at a constant speed therefore we can conclude that gravity slows down time!

The bending of space-time due to a large mass

Sir Arthur Stanley Eddington first proved this light bending in 1919 when he observed a solar eclipse in Principe (near Africa) taking pictures that showed the deflection of light from star passing by the sun which in normal circumstances are obscured by the Sun’s brightness. He compared them to pictures of a star when not in the presence of the Sun and showed an obvious deflection that showed conclusive evidence that General Relativity trumped the Newtonian World.

 

 

There is a particular type of star that has such a great mass that it creates a ‘well’ in space-time, a Black Hole. As a lot of you will know a black hole is a star that has a sufficient mass that it collapses in on its self where no light can escape. This mass warps space-time so much that it can be thought of as to fall into space-time or create a ‘well’ in it (see picture). The rim of this ‘well’ is the event horizon where the bending of light is so great that it falls into the ‘well’. If we were to use the trampoline analogy then it would be like putting a bowling ball of incredibly high mass (assuming the elastic sheet was unbreakable and the trampoline was very high up). A black hole’s great mass means that we could use it for time travel. As I have already mentioned gravity can slow down time, therefore if we managed to maintain an orbit around a black hole without being sucked in we could theoretically age slower than somewhere else, lets say Earth. So when we returned to Earth we would be further in the future than if we had stayed on Earth.

A black hole creating a ‘well’ in space-time

 

 

 

 

 

 

This great mass and curving of space-time also opens up the possibilities of wormholes (a hole that links two points of space). It supposes that two black hole ‘wells’ could join together and make a tube in space-time linking these points in space. However the chance of this happening is miniscule and if it did happen there is the problem of maintain this link.

Wormholes can be used to cross great distances in space

 

I hope you have enjoyed my blog that has touched upon the brilliant concept of space-time!

Christian Tuckwell-Smith – Farnsworth

 

Sources:

Stephen Hawking – A Brief History of Time

http://en.wikipedia.org/wiki/Arthur_Eddington

http://www.youtube.com/watch?v=f0VOn9r4dq8

http://www.youtube.com/watch?v=WHRtdyW9ong

Chemical Olympics

I get bored easily. Very easily. Since the Olympics are beginning soon I decided to put together a list of world champion substances and materials; unfortunately we only award gold here. Times-a-wasting, so here we go!

Most acidic:

The chemical structure of fluoroantimonic acid.

Our first winner is fluoroantimonic acid (HSbF6). This superacid is 20 quintillion times stronger than 100% sulfuric acid. It is formed by the exothermic reaction of hydrogen fluoride (HF) and antimony pentafluoride (SbF5); although effectively ‘naked’ the proton is always attached to a fluorine atom by a very weak dative bond which is why it is so acidic.

Most basic (alkali):

A superbase has a very high affinity for protons and is easily destroyed by water, oxygen and carbon dioxide due to deprotonation. So I will say that the winner here is the hydroxide ion (OH). However although it is the strongest base possible in aqueous solutions, stronger bases exist, just not in water.

Most corrosive:

Coming in as joint winners Argon or Oxygen plasma are the most corrosive substances in the world. They can be made to oxidize just about anything down to its simplest molecular oxide whether it be glass, metal or a polymer, it makes no difference. The plasma is made in-situ by streams of argon and oxygen that are heated by a radio frequency power supply. The atoms of gas can be heated to insanely high temperatures and values as high as 100,000,000 Kelvin have been reported. Want something corroded? Just throw it in, it will disappear quickly enough.

Densest:

Osmium. Nothing more. Nothing Less.

Osmium wins as the densest naturally occurring substance at standard temperature and pressure at 22.59g/cm3. It wins by 0.03g/cm3 just pipping Iridium to the title.

Hardest:

Diamond? Not any more, as lonsdaleite (also known as hexagonal diamond), a carbon allotrope, wins as the hardest substance. It forms naturally when graphite-containing meteorites strike the earth. The immense heat and stress of the impact transforms the graphite into diamond, but retains graphite’s hexagonal crystal lattice. A pure simulated sample was found to be 58% times harder than diamond.

Strongest (tensile):

Walls of carbon nanotubes.

The winner here is (multiwalled) carbon nanotubes, yet another carbon allotrope, this time with a cylindrical structure. It has the highest tensile strength of any material yet measured, with labs producing them at a tensile strength of 63 GPa (yet this is still well below their theoretical limit of 300 GPa).

Highest Young’s modulus:

Finish(ing first). The Diamond standard.

It was bound to win something; diamond is the substance with the highest (measured) Young’s modulus. The world’s most famous carbon allotrope has a gleaming Young’s modulus of 1220 GPa (pun intended).

Toughest:

(Titanium-based) Metallic glass. Looks just like metal.

Metallic glass, created by scientists in California, is found to be the toughest material on the planet, beating steel. The glass is microalloy made of palladium that has a chemical structure that counteracts the inherent brittleness of glass, but maintains its strength. It’s not very dense and it is more lightweight than steel, with comparable heft to an aluminium or titanium alloy.

Most electronegative:

As every educated chemist should know, fluorine wins as the most electronegative element with an electronegativity of 4.0.

Most electropositive:

Francium in water = Bad, bad idea

Francium wins as the most electropositive element. It is at the bottom of its group on the Periodic table and it loses electrons very easily.

Highest melting point:

Tantalum hafnium carbide (Ta4HfC5) is the substance with the highest melting point at 4488 Kelvin. This beats carbon which only has a melting point of 4427 Kelvin.

Highest boiling point:

Here I am going with joint winners. Either Tantalum carbide (TaC) or Tungsten wins, as they both have boiling points that range between 5770-5950 Kelvin.

Most flammable:

Burns through sand. Nuff said.

Chlorine trifluoride (ClF3) explodes as the most flammable substance on the planet (the puns just keep coming). An extremely powerful oxidizing agent, chlorine trifluoride is extremely reactive with most inorganic and organic materials, even plastics, and will initiate the combustion of many materials without a source of ignition. If that’s not scary enough, in an industrial accident, a spill of 900 kg of chlorine trifluoride burned through 30 cm of concrete and 90 cm of gravel beneath it.

Most radioactive:

Gulp !

Polonium-210, I would say, wins as the most radioactive substance on the planet. It is so radioactive that it glows blue because the air around it becomes excited by the radiation it releases.

Most toxic:

Mr Plastic, in the flesh.

The winner here is the botulinum toxin (C6760H10447N1743O2010S32), produced by the bacteria Clostridium botulinum and used in Botox, is the most toxic substance on the planet. In fact, an amount equal to a grain of salt would be enough to kill a 200 Ib man.

Fastest (natural) acceleration:

Try to blink and you’ll miss it.

It is really chemistry but the Pilobolus fungi can accelerate its spores at roughly 20,000 G; that’s equivalent to 33,381ms-2 at sea level or launching a human through the air at 100 times mach speed. Now that’s fast!

Although I deviated a little from chemistry near the end, I hope you enjoyed reading about these world champion substances and materials. If you disagree with any of them or think I should include another category feel free to comment.

Sources:

http://en.wikipedia.org/wiki/Orders_of_magnitude_(density)

http://en.wikipedia.org/wiki/Lonsdaleite

http://en.wikipedia.org/wiki/Fluoroantimonic_acid

http://en.wikipedia.org/wiki/Superbase

http://chemistryiit.blogspot.co.uk/2008/11/super-acids-and-super-base-concepts.html

http://en.wikipedia.org/wiki/Ultimate_tensile_strength

http://www.popsci.com/technology/article/2011-01/new-metallic-glass-toughest-strongest-material-yet

http://en.wikipedia.org/wiki/Young’s_modulus

http://answers.yahoo.com/question/index?qid=20070712141046AApzEj2

http://en.wikipedia.org/wiki/Chlorine_trifluoride

http://web.archive.org/web/20060318221608/http://www.airproducts.com/nr/rdonlyres/8479ed55-2170-4651-a3d4-223b2957a9f3/0/safetygram39.pdf

By Myles Scott – The Demotivator

Monday-Tuesday

I rolled up at the University of Hertfordshire eager, ready and prepped for a hard day of work. I’d tried to conceal the bags under my eyes from accidentally getting ready an hour before I needed to (Reading emails properly has never been my strong-suit) and grinned a slightly weary grin. Then the day really began. There was the requisite meet-and-greet with the head of department Dr Pinfield, and he showed me and the other couple ofstudents around all the various bits of the department we’d be getting to know quite well. Namely, the room with our desks in and the canteen. As I saw the postgraduates sitting in front of computer screens covered in lines of coding I had a feeling that this astrophysics business was more about number-crunching and less about stargazing than that Brian Cox fella would lead you to believe! Turns out, I was absolutely right! Within roughly an hour of getting introduced to my desk (replete with temperamental computer and ominous telephone) I was getting down to some serious spreadsheeting. Now, you may think that you have experience with spreadsheets, that the few IT lessons you spent learning how to divide a cell by another cell were hard work. When you have a spreadsheet that is 500 rows long and 20 columns wide, however, the story is somewhat different!

This was an astrological database, created for me by my supervisor Ben, showing various groups of objects that might be linked together, their movements in the heavens and their magnitudes of brightness. My first task was to sort out the objects that seemed to be moving similarly to one another, as this would mean that they were (hopefully) in some sort of binary arrangement. If two objects are close together and moving at roughly the same rate (This is measured by a process called Proper Motion*) and in the same direction then chances are they’re a binary! Whether or not one or more of the objects is a Brown Dwarf comes later on in our calculations.

Now, all this talk of databases and celestial motion is probably making some of you weak at the knees, and I don’t blame you one bit! Some of the calculations were pains in the backside, but luckily for me, I traded in people skills for number skills a long time ago, and set about squaring this, subtracting that, and performing a logic calculation based on the suitability of the other. Pretty soon we had a nice list of stellar objects that we could begin investigating further.

Wednesday

We’ve now begun to use images collected from the SDSS (Sloan Digital Sky Survey) and the UKIDSS (UK Infra-red Deep Sky Survey) surveys to actually try and see some of the objects behind the numbers. At first, trying to orientate yourself using these pictures is difficult, which is annoying when you’re trying to find where the two objects are in relation to each other, but nevertheless I’m pressing on and trying to pick up the knack. Sometimes this is made especially difficult with the UKIDSS pictures, because, although they show the objects we are looking for more clearly, the orientation is often different for each picture! This basically means that in one picture north is up, but east is left, and in another picture north is down and east is still left! Needless to say this is really confusing, but once you’ve finished tilting your head to the side you can pretty much understand where you are.

That’s pretty much it for the moment, but I’m sure I’ll have a whole smorgasbord of astro-facts next week! Mine’s a brown dwarf with a slice of lemon, Chin-chin!

Harry Saban – The Octave Doctor

*Proper Motion: This is used to describe the movement of a celestial object, relative to the center of the solar system, using a sort of co-ordinates system. The co-ordinates work like this:

File:Ra and dec on celestial sphere.png(Image from Wikimedia Commons)

Right Ascension (RA) is like longitude but for space, as if we were looking from the center of a sphere to its inner surface. Unlike normal co-ordinates it increases from right to left and has no negative values.

Declination (Dec) is basically the angle from the equator, and goes from +90 (North Pole) to -90 (South Pole).

Both of these values are generally measured in Arc-Seconds (1/3600 of a degree), Arc-Minutes (1/60 of a degree) or Degrees (1/1 of a degree).

The speed of light, and more precisely near the speed of light travel, has always fascinated me, but thinking about it raises the very interesting question, what happens if you actually get to, or near, the speed of light?

If we put aside the problems of getting an object up to that speed and simply imagine a bowler throwing a baseball and it spontaneously accelerating up to 0.9c, we only need to follow basic physics to predict what will happen.

A very simple answer to the above question is a lot of things, none of which are very nice, and none of which end well for the batter (or anyone nearby for that matter). At this speed (0.9c for those with a bad memory) everything else is practically stationary, the batter is stationary, the bowler is stationary, the spectators and fielders too, even the air molecules are stationary. Air molecules vibrate about at a rather pedestrian few hundred meters per second, where as the ball is moving at a few hundred million meters per second (269,813,21,.2 m/s to be precise). This means, as far as this thought experiment is concerned, that they are stationary. As a result, the laws of aerodynamics don’t apply here, the air molecules have no time to be forced out of the way and simply smack into the ball. This happens with such force that the oxygen and nitrogen in the air actually fuse with the carbon, hydrogen and oxygen in the ball. Each collision releases a huge burst of gamma rays, x-rays and other forms of energy, including light and heat.

This EM radiation expands outwards in a bubble centred on the pitcher’s mound, ionising any air molecules it meets, creating a shockwave of superheated plasma, approaching the batter at nearly the speed of light, only just ahead of the ball itself.

This fusion continues to occur on the leading edge of the ball as it moves through the air, slowing it down, similar to a rocket flying tail first while firing its rockets. However, the force of the on-going thermonuclear fusion is insufficient to even barely slow the ball. It does however begin to vaporise the surface, throwing out debris and particles at speeds close to the speed of light, this causes two or three more rounds of fusion as it hits the ionised air around it.

After around 70 nanoseconds the ball reaches the batter. The batter hasn’t even seen the ball leave the bowlers hand as the light carrying this information reaches the batter only 0.6 nanoseconds ahead of the ball. Collisions with the almost stationary air molecules has eaten the ball away to a slug of hot, ionised, expanding plasma, smashing into the air and creating even more fusion as it goes. The x-ray front of the plasma wave reaches the batter first; the disintegrating ball reaches the batter a split second later.

When the shockwave and what’s left of the ball eventually reaches the batter it’s still moving at a fair old lick, still reasonably close to the 0.9c it left the now vaporised bowler at. This shockwave scoops up and carries the batter, backstop and catcher all back through the stadium wall, as they and the wall begin to disintegrate. The shock wave of high energy EM waves and super-heated plasma continues to expand, and within the first 3 microseconds it has consumed the two teams, the stadium the car park and the surrounding half a mile of neighbourhood.

From an observers point of view on a distant hill, the first thing they would notice is a blinding flash of light, outshining the sun for several seconds and then, as it fades, a growing fireball rising into a mushroom cloud. The surrounding one and a half miles of city would be charred to a crisp and completely flattened, and a further two miles would have superficial damage, such as blown out windows and damaged roofs.

By an object, in this case a baseball, traveling at only 90% the speed of light, a nuclear explosion, somewhere in the region of about 1 kiloton has occurred, destroying a sizable chunk of populous city. Now this may seem an unlikely scenario, but it raises the interesting question, what if it did happen? In a future of faster and faster travel, we may have to severely limit the places where we can travel incredible speeds, or face the consequences…

N.B. A careful reading of the major league baseball rules implies that this would be a foul ball and the batter would be permitted to advance to first base, at least, where first base used to be

References:

http://nuclearweaponarchive.org/Uk/UKArsenalDev.html

http://en.wikipedia.org/wiki/Yellow_Sun

http://en.wikipedia.org/wiki/Nuclear_weapon_design

Two A-level physics books and my trusty calculator for most of the numbers

Pictures from:

http://what-if.xkcd.com

Alex Davis

Black holes. One of the universe’s most destructive forces, capable of tearing stars and planets to sheds, and swallowing them whole. Yet, scientists believe they could actually be the key to shaping the many millions of galaxies in the universe, creating and holding life itself. But moreover, scientists believe black holes could finally answer mankind’s most potent question: What came before the Big Bang?

 

The problem is, researching black holes is near impossible. By definition they are invisible, and current theories that seem to be able to explain everything else in the universe, collapse when applied to black holes.

 

We know black holes form when the most massive stars reach the end of their life. Red giants explode into a supernova, before finally violently collapsing into a point, creating the black hole. The reason something so small can have such a great gravitational field that not even light can escape, is due to the effect of mass bending space, shown by Einstein’s famous Theory of Relativity. The more massive an object, the more it bends space, like putting a heavy ball onto a trampoline. When this mass concentrates into a small area, the distortion and bending of space greatly increases. As black holes are so small and yet have such large masses, the distortion of space is phenomenal, giving it the quality of the event horizon. Beyond this point, space has bent so much, and the gravitational pull is so large, nothing can escape. A common analogy used by scientists is a waterfall. The closer water is to the drop off point, the faster the current. Once the water flows faster than you can swim, there is no way you’ll ever escape plunging to the bottom, representing the inescapable event horizon of the black hole.

 

But how can this possibly help scientists find out what came before the beginning of time? Well, it’s all down to the similarities of the black hole, and the big bang theory. According to the accepted current theory, the universe has been expanding for millions of years, and will continue to do so, but this expansion had to start somewhere. The theory states that expansion started from a single point in the universe. A singularity.

 

The difficulty is that the singularity, the very centre of the black hole, is where physics breaks down completely. It just doesn’t work anymore. Einstein’s Theory of General Relativity perfectly explains the massive, such as the stars and space, but when you put an incredibly large mass into such a small object, something strange happens. According to the theory, the singularity takes up exactly no space at all, and when implemented into the maths of general relativity, we get the answer physicists fear most. Infinity. This would mean that at the centre of a black hole, gravity is infinite, time stops, and physics collapses. The singularity is when our understanding of nature breaks down. So clearly there is a fundamental flaw in physics? Einstein knew of this flaw, but hoped such an object would never actually form, and even wrote a convincing paper proving this. At the time it was reasonable, but in the 1970’s pictures showed thick dense clouds of x-rays which quickly disappeared, giving convincing evidence of what we now know as the black hole.

 

But general relativity is very good at describing the very large, so to describe the singularity, quantum mechanics was used, which deals with atomic and sub atomic scale objects. But this is not as simple as it seems. Because quantum mechanics describes the minute, it can’t and doesn’t describe gravity, as it makes a negligible effect on atoms. This would normally be irrelevant, but when describing the singularity where gravity is phenomenally strong, the two theories just don’t mix.

 

To overcome this problem, theorists attempted to extend quantum mechanics to describe gravity, known as Quantum Gravity to try and link the famously incompatible General Relativity and Quantum Mechanics. But when inserted into the equations, again the result came up as infinity. In fact, it resulted in an infinite amount of infinities. Quantum Gravity had fallen apart. The theories were completely incompatible. This told scientists that at best, the theories were just an approximation of the universe. It meant the collapse of all physics as we know it.

 

Getting quantum mechanics and general relativity to work together has been the biggest challenge for physicists. Finding something to link them, or even finding new theories entirely to explain everything as a whole has been, and still is the current goal of theorists. Although it appears black holes have messed everything up, they represent a marvellous opportunity for physics. If the universe is expanding, then it must once have been more compact. A singularity.

 

So, if scientists can discover what is happening at the singularity in the black hole, this could help hugely in understanding and unlocking the secrets of what came before the Big Bang. Unfortunately with our current technology, we have only just been able to detect a possible black hole, let alone discover what happens inside one, and even these findings are still not 100% certain. For now, it’s all a big puzzle for the theorists, using clever maths and wondrous ideas to determine what might actually happen at the singularity, and until we can physically research black holes, we can never know for sure. There is hope yet though. Due to the impossible bending of space by a black hole, outside the event horizon, light from stars around the black hole is warped and reflected to produce a ‘halo’, a ring of light surrounding the event horizon. This would be possible to see, so discovering and observing a definite black hole for the first time is possible. Until then, we can only imagine one day, being able to answer the question: ‘What was there, before the Big Bang?’

 

Sources:

BBC Horizon, ‘Who’s Afraid Of A Big Black Hole?’

By Will Slack

Pop goes the nanobubble!

Look bubbles!

Ah bubbles, what wondrous things. As children (and even now as a young adults) bubbles have fascinated us all and brought youthful joy to our lives. But now a special type of bubble could revive polluted lakes, clean tankers and computer chips and even kill cancer cells (I won’t be talking about the cancer cells in this post unfortunately). It is called the ‘nanobubble’ and for all intents and purposes it should not exist. So to get to the heart of the conundrum, how exactly does a bubble ‘work’?

The extremely thin film of liquid that surrounds a soap bubble, for example, is only sustained because the pressure of air inside the bubble is higher than the pressure of air outside the bubble, so the air pushes out against the surface tension of the liquid molecules. As air gradually leaks out through the bubble’s thin, porous walls, this excess pressure is gradually reduced, and when it is reduced enough, the bubble bursts.

This is especially true for small bubbles. The smaller a bubble is, the more tightly curved the film is and the more concentrated the inward force that the pressure has to counterbalance. Below a certain size (which also depends on the liquid enveloping the bubble among other factors) the internal pressure needed to counter the surface tension simply becomes too great; would-be nanobubbles collapse even before they can form. Or do they?

In 1994 in a laboratory in Sweden, John Parker was conducting an experiment measuring the repulsion between two water-resistant surfaces immersed in water. As they were forced together, the repulsive force between them first increased as was expected. Then, at a distance of a few hundred nanometres, it suddenly dropped off. Why?

A few years later Phil Attard provided a semi-plausible explanation. He suggested that if the surfaces were populated by nanoscale bubbles, these would join forces to minimise their surface tension as the surfaces neared each other, just as two soap bubbles blown in air merge. This effect would draw together surfaces that would otherwise repel each other.

Now for some numbers: according to physics, for nanobubbles to even exist they would need internal pressures of around 100 atmospheres! Now although that sounds implausible, in 2001 (with the help of his trusty scanning probe microscope), Attard and his colleague James Tyrrell spotted hemispherical nanoscale structures growing on hydrophobic silicon surfaces immersed in water. Subsequent spectroscopic measurements showed the structures were filled with gas. So it seems that nanobubbles do exist… but no-one can say how.

But the nanobubble doesn’t stop surprising us there, as things got weirder when James Seddon (at the University of Twente) used an atomic force microscope to take a closer look at the structure of the nanobubbles. Now, if they were indeed filled with gas, the pressures inside should force molecules out through the bubble walls at an extreme rate. He wasn’t disappointed as the rapid flow of molecules from the bubble’s apex could be felt pressing against the probing tip of the microscope. The strange part was, as Seddon put, “The bubble has maybe a thousand molecules inside it, and it’s losing approximately 1 billion gas molecules per second.”

But how can this be!? Researchers could only suggest that something must be recycling the molecules back into the bubble, perhaps at the join where the bubble wall meets the surface on which it sits. However observing such a flow directly would require getting inside the bubble, which is impossible without popping it. With every possible explanation brought a host of unanswerable questions with it and yet our little nanobubble friend happily persists in its existence.

So what happened to this special bubble performing those amazing tasks, you ask?

Well a team from China, led by Pan Gang, has a simple plan to revive a heavily polluted, oxygen deprived lake by pumping it full of oxygen again. To do this he will use his own patented mechanism which involves putting a suspension of lakeside clay in chilled water and saturating it with oxygen bubbles. All but the smallest bubbles float away, but microscopic imaging confirms the presence of oxygen bubbles just 10 nanometres in diameter in the clay. Spraying the resulting slurry on the lake’s surface pushes the polluting cyanobacterial blooms to the lake bottom within minutes. The chilled water warms up in the body of the lake, allowing larger oxygen bubbles to form at the interface between the clay and water. These bubbles break free and break down the algae, re-oxygenating the water. To top it off, the process is energy efficient and non-polluting, involving only native soils from the lake’s own edge.

The results from this mechanism? Experiments in a 50,000-square-metre area of the lake cleared the whole centimetre-thick algal bloom in half an hour. The following day, concentrations of ammonia, nitrates and phosphorus compounds in the lake water (products of the cyanobacterial metabolism and the source of foul smells) had fallen dramatically. Four months later, underwater vegetation was growing prodigiously and plankton populations were thriving again. Impressive.

Using more or less the same principles, nanobubbles created on an electrified surface could help to keep the surfaces of large ships and small silicon wafers (for computer chips) clean. In the case of cleaning silicon wafers, nanobubbles would be a much more beneficial alternative to the multi-cycle method of cleaning that is currently in use (which also uses environmentally hazardous chemicals).

Now how’s that for something that physics says shouldn’t exist.

Physics loses… for now

Source:

http://www.newscientist.com/article/mg21528721.900-the-wonderworking-bubbles-that-physics-cant-explain.html?cmpid=NLC|NSNS|2012-0907-GLOBAL|mg21528721.900&utm_medium=NLC&utm_source=NSNS&utm_content=mg21528721.900

by Myles Scott – The Demotivator