Wednesday, 1 June 2016

Ep 162: Pulsating Pulses


2016 is the International Year of Pulses, which aims to heighten public awareness of the nutritional benefits of pulses as part of sustainable food production aimed towards food security and nutrition. I spoke to Daniel Tan from the University of Sydney's Faculty of Agriculture and Environment about his research into pulses, including genetic resistance to heat waves and climate change, plant physiology and genetics, crop modelling and why he is known throughout the University as "The Hot Scientist".

Feel free to leave your favourite pulse recipe below in the comments! Some good ones are here.

Listen below:

 

Songs in this episode (all Creative Commons Attribution Noncommercial (3.0)):
  1. Certain Death (Pulse Mix) by Future Boy;
  2. Dj Rkod - Pulse (George Ellinas Remix) by George_Ellinas;
  3. Pulsed Sensations by AudioLogic;
  4. Pulse by Pitx;
  5. Pulse by Psychadelik Pedestrian;
  6. God is hot (feat. MommaLuv SkyTower) by Wired Ant.
     

Sunday, 28 February 2016

Ep 161: 2016 Pulses and Pulsars



Happy 2016! This week, I spoke on ABC Radio Central West about some of the science we can expect in 2016:
  1. 2016 is the International Year of Pulses, which aims to heighten public awareness of the nutritional benefits of pulses as part of sustainable food production aimed towards food security and nutrition. The Year will create a unique opportunity to encourage connections throughout the food chain that would better utilize pulse-based proteins, further global production of pulses, better utilize crop rotations and address the challenges in the trade of pulses.
  2. 2016 will also see some interesting astronomical events, although it will be hard to beat 2015. My favourite upcoming events are:
    • The Juno mission to Jupiter 
    • The continuing Akatsuki mission to Venus. This mission is a testament to the usefulness of maths: originally, the orbiter could not get into orbit around Venus due to on-board failures, and orbited the Sun for 5 years, until the mathematicians got together and figured out how to get the craft back into orbit around Venus using the remaining working thrusters. After 5 years!
Listen in to this show below on ABC NSW's soundcloud page, or grab the mp3. As always, thanks for Kia!

Sunday, 14 February 2016

Cricket teams and the efficient frontier

Cricket and financial markets have a rich, intertwined history, from Vincent back to Waugh/Warne, Lillee/Marsh and Keith Miller. So, I don't think we necessarily need a new cricket market, but let's make one anyway, and refresh my financial maths and linear algebra at the same time.

Cricket, especially its shortened forms, is seemingly becoming a batsman's game. Bats are bigger, fields are smaller, fielding and bowling restrictions make it difficult to pressure the batsmen, players are fitter and the game is more professional than it has ever been. The trend towards bigger scores is shown clearly in men's One-day International (ODI) cricket. The following chart shows the yearly average score each team scored when batting first in an ODI*, with the black line (ODIAll) being the average of all games in that year. The "Associate" line refers to Associate cricket teams that played games the International Cricket Council (ICC) deemed worthy enough to have ODI status, and also those World XI, Asia XI and Africa XI matches that were in vogue about 10 years ago and were also given ODI status. Individual Associate nations did not play enough games to create enough meaningful data for this analysis.



*Only innings that went for 50-overs, or where the team was bowled out, were counted so as to take out the influence of rain.

In our financial market, each of the series above is a stock, whose value is that team's average ODI score batting first in that year. The ODIAll series is the index for this particular stock market (like the S&P 500 or All Ordinaries). The upward trend in ODIAll is clear, and the following shows ODIAll data with an exponential fit. An exponential fit is what you would expect if the stock was growing with continuously compounding interest. The fit is pretty good (R2 = 0.8). The other dots are the country data and show the scatter (and noise) in the data set. I've gone back to 1980, as before then there were few games played annually.


Such trends are evident in other sports, but not all sports are as focused on increasing scores. Premier League football shows no such scoring trend, total home runs in Major League Baseball ebbs and flows depending on a number of factors including the amount of steroids being taken, but there has been a steady increase in strike outs over the last 20 years.

Let's do some maths. What we want to do is determine in which teams we should invest. We don't necessarily want to invest in the teams that regularly produce the highest scores. We want to pick the teams that are improving - that is, their stock prices are going up so we'll get a good return. For instance, Australia has been dominant in ODI cricket for some time; it may not be a good investment if it can not continue to grow its already large yearly average. On the other hand, Associate teams are playing more ODI cricket and Bangladesh is ever improving, perhaps they would be better investments, although likely to be more risky than an established team. Maybe we'd be better off just buying the ODIAll Index.

Inline with Modern Portfolio Theory, I used the methods in these two articles:
Yes, I did it in Excel, and yes I realise that if I was any sort of data analyst I would have done it in R, but if you can't go 80% of the way towards solving the problem in Excel, it's not a problem worth solving.

The following chart shows the average percentage return and standard deviation of each country's yearly stock price. On average, Australia increases its price by ~1%, with a standard deviation (risk) of 8%. Interestingly, South Africa, for a similar risk, has a ~2% return. Bangladesh is the BRIC of this market, rapidly improving over the last few years, but with a relatively high risk. The Associates are far too risky to invest in just yet. 
To determine your portfolio, you don't just need the risk/return values, but we also need to know whether an increase in one country's stock will cause an increase (or decrease) in another. This is measured by covariance. In our case, the prices of all countries are generally moving upwards over time, however there are some interesting pairs of countries that move together in the same direction (Sri Lanka and New Zealand) and in the opposite direction (Zimbabwe and Bangladesh). I suspect a lot of this is noise. In any case, by knowing that an increase in one stock price will likely see a decrease in another, you can minimise the overall risk of your portfolio by hedging.

To determine which teams we should include in our portfolio, we need to determine the Efficient Frontier. This is the line on which you can not get a higher return from any combination of assets in your portfolio for your choice of risk. For example, if you are happy to take on a risk of 20%, you can't expect a return more than 8% from these assets - yes, it's not exactly the sort of market I'd want to buy into, but let's keep going...

The next thing we need is the Capital Market Line (CML). In any market, there may be what is known as a "risk-free asset" - an asset which gives a guaranteed return with no risk. In financial modelling, government bonds assume the role of risk-free asset, as they have a known return and as the government has almost zero chance of default, are assumed risk-free. The CML is the line drawn from the point of the risk-free asset (on the y-axis) such that it is tangent to the efficient frontier. The intercept point is known as the market portfolio. Along the CML, your portfolio contains various amounts of the risk-free asset and the market portfolio (the risky asset).

There is no real equivalent to a risk-free asset in this market, so I've assumed it to be 0.5%, which is, at time of writing, about the price of a German 10-year government bond (this market is based in Germany, for no particularly good reason. Perhaps a German financier, tired of his team being ranked between Gibraltar and the Isle of Man, wanted some fun).

The market portfolio allows you to short sell; that is, sell stock you don't currently own. Perhaps you've borrowed it and sold it on. But you have to buy it back to give it back to the person from whom you borrowed it. You'd do this if you were expecting the price to drop so you would be buying it back at a lower price than you sold it, or as in our scenario, as a hedge. You can also determine the optimal portfolio if short-selling is not allowed, and the minimum risk portfolio. The weightings are below. Essentially, if you don't mind a bit of risk, buy Bangladesh and South Africa. If you want a bit more safety, replace Bangladesh with Australia.



Market Portfolio No short selling Minimum Risk Portfolio
Australia -0.09 0.01 0.26
England -0.18 0.00 0.00
New Zealand 0.10 0.06 0.00
India 0.03 0.00 0.10
Pakistan 0.11 0.05 0.07
West Indies 0.00 0.00 0.09
South Africa 0.44 0.35 0.23
Sri Lanka -0.04 0.00 0.07
Zimbabwe 0.20 0.16 0.09
Bangladesh 0.42 0.36 0.09
Associate 0.00 0.01 0.00


How are these portfolios going in 2016 (at Feb 14)? Well, noting that some of the teams have yet to play this year (so I have assumed they have a 0% return), if you'd bought the ODIAll index, you'd be up 7%, the minimum risk portfolio is down 0.9%, the no-short-selling portfolio is down 7.6% and the market portfolio is down 13.1%. This is inline with the amount of risk in each portfolio, but not a good result. Still, the year is young.

Would I ever use this technique to develop a portfolio for such a market? I don't think so. This method weights a team's return from 1981 to 1982 the same as the 2009 to 2010 return. In cricket, I suspect you need to look recent form as opposed to historic, and be more specific with regards who each team is playing, and where. There's probably not enough data for the correlations and covariances to really mean anything either.

Can the ODIAll Index continue to increase? This market is much like a real financial market - you can not expand forever in a world of limited resources. It has to come to an end at some point. There are ways, however, that teams could attempt to increase their own prices in the short-term. Australia, which has traditionally been very poor at playing nations it doesn't deem good enough to take the field with, could actually start to play some games against Bangladesh, Zimbabwe and the Associates; the financial markets analogy would be a company outsourcing its manufacturing to countries where they don't pay their workers well. This approach would not necessarily work for teams like India and Sri Lanka, who have been plundering week bowling attacks and bolstering their averages for some time. But at least they are attempting to grow the game, perhaps cognisant of the fact that for long periods of time they were also not particularly good (some Australia, as a foundation Test nation, never really had to think about). It will be interesting to see if India continues to do this as they take over the ICC. The Big 3 would do well to remember that they are big because of the international market and that it should be nurtured. To the (previous)-ICC's credit, the international ODI market has liberalised since around 2005, with more countries playing games with ODI status. However, it remains to be seen whether you'll ever be able to buy stock in individual Associate nations in our market.

Many things could influence this market in the future. How regulated is it going to become? Will the number of nations playing ODIs grow or shrink? Where will technology trend, what rule changes are going to come in? Or will ODI cricket die in the face of T20 cricket?

Wednesday, 13 January 2016

More holiday science experiments

We've previous put up a demonstration and explanation of capillary action using flowers, but this one is also quite fun. Simply fill two small glass containers with water, putting plenty of blue food colouring in one, and yellow in another. Connect the two containers to an empty middle container with absorbent paper. The paper absorbs the water, and through capillary action, the water moves through the paper to the middle container. After a few hours, this middle container has the same amount of water as the external containers, and you can see the effects of mixing blue and yellow (it makes green).
A photo posted by Marc West (@westius) on

Make sure your paper is burly.

Thursday, 24 December 2015

Ep 160: 2015 The year of light



2015 was a magnificent year for physics. Not only was it the International Year of Light and light-based technologies, it was an outstanding year of astronomical achievement, culminating with the magnificent New Horizons photos of Pluto. It was also 100 years since the Theory of General Relativity was published, and 50 years since the Cosmic Background Radiation was discovered.

Australia also broke a couple of astronomical world records: The most people stargazing across Australia, and in a single location at ANU. One of the organisers of this world record was Tom Gordon, a science communicator at The University of Sydney who runs Kickstart Physics (Instagram), which are physics workshops aimed at year 12 science students and teachers. Tom, along with Christie McMonigal and Shane Hengst, runs the STEMPunk podcast, chatting about science communication and Science, Technology, Engineering and Mathematics (STEM): Communicating scientifically with science communicators.

Who better to talk to about this splendid year in Physics than Tom?

Listen in here:


Songs in this episode (in order of play - all Creative Commons Attribution Noncommercial (3.0)):
  1. Sharks with Lasers by spinmeister;
  2. Red Giant by Fireproof_Babies;
  3. Fate of the Sun by Fireproof_Babies;
  4. Beyond Jupiter - Instrumental by Ivan Chew;
  5. Spaced Invaders 2011 (90 BPM) by coruscate
     

Tuesday, 13 October 2015

Who you gonna call?

Dial 000 - Police, Ambulance, Fire Brigade...... Or Science!

Monday, 21 September 2015

Ep 159: Wedding cost, marriage success and cats

From a recent chat with ABC Central West, this week is definitely a correlation of the week. Two separate stories on the topic of love and attachment highlight a couple of statistical concerns you need to be wary of when drawing conclusions from research:
  1. The correlation of wedding / engagement ring cost and marriage longevity (concern: correlation does not necessarily equal causation);
  2. Does your cat really love you? (concern: sample size)
Listen in below or on the mp3 (and all credit again to ABC and Kia).




References:
  • Francis-Tan, A., & Mialon, H. (2015). A DIAMOND IS FOREVER” AND OTHER FAIRY TALES: THE RELATIONSHIP BETWEEN WEDDING EXPENSES AND MARRIAGE DURATION Economic Inquiry, 53 (4), 1919-1930 DOI: 10.1111/ecin.12206  
  • Potter A, & Mills DS (2015). Domestic Cats (Felis silvestris catus) Do Not Show Signs of Secure Attachment to Their Owners. PloS one, 10 (9) PMID: 26332470

Wednesday, 26 August 2015

Science Week 2015

National Science Week has come and gone for another year. This year, I spent a lot of it down at Canterbury Public School where I am their tamed scientist as part of CSIRO's Scientists in Schools program. It was a lot of fun, and we walked away with a world record - more on that in a bit. Here's some of the cool stuff we did:



Above is my box of household products for various experiments, and the results of cabbage indicator. Cabbage indicator is made by simply boiling purple cabbage. The resultant solution contains a chemical called anthocyanin which exists in an equilibrium of three forms depending on the ph, allowing a wide range of colours. We used mould remover (strong base), window cleaner (mild base), lemon juice, vinegar and tartaric acid (mild acids).



We've made corn flour slime before, but if you make it with tonic water, it will fluoresce under UV light and glow in the dark. Tonic water contains quinine, which apart from fluorescing, is also a preventative for malaria (which is why it was put in tonic water in the first place). And here's some phosphorescence:



None of the kids had seen an overhead projector before. This demonstrated some basic optics regarding mirrors and light travelling in a straight line, as well as how old I now am. The food colouring / milk / detergent experiment works in the same way our detergent-powered boat works, noting that the fat in the milk helps keep the food colouring separate (it doesn't readily dissolve until the soap is added).



Liquid nitrogen is always good (as was the liquid N2 ice cream we made), as is entertaining your local MP and making a homemade periscope.



And on that world record, we participated in the world record stargazing attempt for most number of people gazing at the stars at once across many sites. And we got there (unofficially at the time of writing anyway). It was dark, I didn't get many shots, but I did get this one of our planetarium and star demonstrator...




Tuesday, 11 August 2015

Ep 158: Food science with ABC Radio

Every month, I chat with ABC Central West and the science topics of the day, and this week we chatted food, in particular:
  1. Consumption of spicy foods may lead to a lower risk of death (and a little about correlation and causation - I really should do some more correlations of the week)
  2. Human brain evolution needed carbs
  3. 3D printed food
 Have a listen below, or on the mp3 - all credit to the ABC (and the wonderful host, Kia).


Thursday, 2 July 2015

Ep 157: Where to now for Cold Fusion?

Big Bang / Cold Fusion

Do you remember Cold Fusion? Remember when electrochemists Martin Fleischmann and Stanley Pons claimed to have achieved nuclear fusion in a bottle on a table in their lab in Utah? That was so 80s! Cold Fusion was quickly debunked and, apart from its appearance in a 1997 Val Kilmer Movie (The Saint), most people forgot about it. So it may surprise you to hear that Cold Fusion research continues to this day, with some “interesting” participants and some extraordinary and surprisingly persistent claims. The most recent International Conference on Cold Fusion (ICCF-19) was the largest yet reflecting a climate of renewed interest.

Dr. Timothy J. Surendonk has a passion for cold fusion, and in this podcast episode, tells its story, of the new players, recent events, and particularly the curious story of the “e-cat.” It isn't heavy on technical science, but rather a more entertaining talk that just might challenge the way you relate to science.

Listen to this show here:



References:
  • Fleischmann, M., & Pons, S. (1989). Electrochemically induced nuclear fusion of deuterium Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, 261 (2), 301-308 DOI: 10.1016/0022-0728(89)80006-3
  • Kim, Y. (2009). Theory of Bose–Einstein condensation mechanism for deuteron-induced nuclear reactions in micro/nano-scale metal grains and particles Naturwissenschaften, 96 (7), 803-811 DOI: 10.1007/s00114-009-0537-6 
  • Kim, Y. (2012). Nuclear Reactions in Micro/Nano-Scale Metal Particles Few-Body Systems, 54 (1-4), 25-30 DOI: 10.1007/s00601-012-0374-6

Songs in the podcast:



Banner: 

    Thursday, 26 February 2015

    Farewell Darren

    It is with great sadness that I let you know that my friend and co-Beer Drinking Scientist, Darren Osborne, passed away in January after a brave battle with brain cancer.

    I've put a few words up over on the BDS website, so I'll direct you over there if you would like to have a look or if you would like to make a charitable donation to the Cure Brain Cancer Foundation.

    The clips in this show might not be new to Mr Science Show listeners, but they are new to those who listened to BDS and are a nice collection of irreverent and ridiculous scientific conversations between us.

    Wednesday, 14 January 2015

    Science for kids - Slime

    Everyone likes slime! And it's easy to make, in its various forms.

    Cornflour Slime:
    All you need is cornflour (made from actual corn - maize - not the "wheaten" version you can get in Australia, which is made from wheat), water, some colouring, a bowl and a spoon. The process is:
    1. Pour cornflour into a bowl,
    2. Stir in small amounts of water until the cornflour becomes a thick paste. I prefer to have the water coloured at this point, as it helps to more effectively spread the colour throughout the slime.
    And that's it. Try stirring the slime slowly (should be easy) and then quickly (should be almost impossible). Then try punching it. I employed a professional hand model for this video.



      Cornflour slime is a shear thickening non-Newtownian fluid - the viscosity of the slime increases as the shear rate (how quickly you stir, how hard you punch) increases. This is because the slime is a suspension of corn starch. The corn starch molecules are large and jagged and when stirred slowly, the molecules have time to move past each other, lubricated by the water. When a large force is applied, the molecules are jammed quickly together and the liquid does not flow - it becomes solid-like. You can keep it for about a week in the fridge before it starts to smell a bit like vomit. You may need to add a bit of water each time you use it, and stir it in slowly (you won't have much choice).

      Packing Peanut Slime (Borax Slime)
      A less cool, but nonetheless fun to make, slime is made from packing peanuts - the stuff used to protect fragile objects when you mail them, move house etc. Packing peanuts are generally made from starch but also contain PVA - polyvinyl alcohol. Place about 5 mL of water in a cup and add about 8 packing peanuts and stir. They will start to dissolve. Continue to add the peanuts until it starts to become thick, and then some food colouring.

      At this point, you need to have gloves on (and eye-wear if you have some). Add 1 mL of 4% sodium tetraborate solution (borax) and stir. You may have some in your laundry as it is used for cleaning clothes. Your goo will now start to become slimey. Once you can make a solid ball out of it, start to wash it with water to wash away any extra borax. After doing this, you can handle it with bare hands.


      Polyvinyl alcohol is a polymer - a long molecule with repeated subunits (monomers). The borax cross-links the polymer chains; that is, it bonds one polymer chain to the next. As you add more borax, more crosslinking occurs making the slime thicker.

      There is a similar slime you can make with PVA glue, although in this case the PVA stands for polyvinyl acetate as opposed to polyvinyl alcohol. The process is the same - the borax provides the cross-linking between the PVA polymers, except in this case the monomer contains an acetate (CH3COO) rather than an alcohol (OH). More on this slime here.

      Saturday, 10 January 2015

      Science for kids - Elephant Toothpaste

      Gooey stuff is always pretty exciting for kids. This is called elephant toothpaste because, well, that's what it looks like. The experiment is fairly simple. The ingredients are:
      • 125ml 6% Hydrogen Peroxide (ask at the chemist)
      • 1 Sachet Dry Yeast (powder) + a few tablespoons of warm water
      • Detergent
      • Food colouring
      • Empty bottle
      • Funnel
      You might want to wear gloves and goggles when handling the hydrogen peroxide. Add the hydrogen peroxide, a few drops of food colouring and a good squirt of detergent to the empty bottle, then swirl the mixture. Separately, combine the yeast with a few tablespoons of warm water and stir until mixed. Put the funnel in the top of the bottle, add the yeast mixture and watch the foam. The bottle will get a little hot (the reaction is exothermic).



      The reaction occurring is hydrogen peroxide decomposing into water and oxygen:
      2H2O2 → 2H2O + O2

      The bubbles are caused by the detergent capturing the oxygen. The foam is water and the colouring is made by the food colouring. The yeast is acting as a catalyst. The first few times I tried this, I was using yeast well past its used by date, and it didn't work very well, so make sure your yeast is relatively fresh. Yeast contains an enzyme called catalase. Catalase is found in nearly all organisms exposed to oxygen, and helps prevent cell damage caused by the by-products of oxygen metabolism. It actually catalyses this hydrogen peroxide reaction in living organisms.

      I did this outside on our grass, and as the by-product is water, it is safe to have on the lawn. If you are inside, make sure you have a tray to capture the toothpaste as it squeezes out. Wearing gloves minimises the chances of your skin coming in contact with hydrogen peroxide. 

      If you want to make the reaction more vigorous - in which case you have to wear proper safety gear - then you can use potassium iodide as the catalyst. But you might not have that lying around the house. There is some more info here.

      Science for kids - detergent powered boats

      This is an easy one, assuming you occasionally clean your dishes. You just need some bread ties, water and detergent. The video is a little unimpressive, but you could dress the bread ties up to make them look like boats.



      Essentially, the detergent is breaking the surface tension of the water, and if you break the surface tension behind the bread tie, the tension in front of the tie pulls it forward. Detergents are surfactants, which means they have a polar end (which is attracted to water) and a non-polar end (which is attracted to oil and grease). This is how detergents (and soaps) bond to both oil and water and hence wash your dishes. Water, without detergent, has a strong surface tension, which is created by the water molecules bonding to each other through Hydrogen bonds. The polar end of the detergent breaks the water surface tension by interfering with the hydrogen bonds at the surface - interestingly, the non-polar ends of the detergent, being hydrophobic, stick up into the air.

      Science for kids - Water Rocket

      Water rockets are one of the classic science demonstrations for kids - exciting, a bit of danger and some interesting science. Make sure you have plenty of space - making this video, I managed to get the rocket to hit the road, a swing set (with no one in it, thankfully) and some trees. We moved to the middle of a cricket field as the rockets can really go a long way. You can buy water rocket kits at toy or sciencey-styled stores. You need to provide a drink bottle, a bike pump and some water.



      The science is quite simple. Using the bike pump, you pump air into the bottle (which already contains some water), increasing the pressure of the air (storing potential energy) until the seal on the rocket bursts. The high pressure air forces water out the bottom of the rocket, which propels the rocket forward. This is an example of Newtown's third law of motion (commonly known by the expression: for every action, there is an equal and opposite reaction).  

      Thursday, 8 January 2015

      Science for kids - Coloured flowers

      This is quite a simple one. Grab some carnations (or other white flowers), a vase, some food colouring and water. Add a generous amount of colouring to the water (20-odd drops), add the flowers, and wait. It can take longer than a day, especially if you haven't quite added enough colouring, so be patient. Here are some shots we took of our red and blue flowers (I reckon you can be more impressive than this!):



      The flowers turned blue quicker than red for me, and others have seen similar things (anyone know why?)

      The science on display is the capillary action of the water - that is, how the flower drinks even without its roots. This ability draws water against the force of gravity up the stem and into the petals. It works because the water evaporating from the petals and leaves of the plant "pulls" water up the narrow tubes in the stem (the xylem) to replace that which is lost. The tubes need to be narrow so that the combination of the surface tension of the water (caused by cohesion in the water - how well it sticks to itself) and the adhesive forces between the water and the walls of the xylem are strong enough to lift the water against the force of gravity. The adhesive forces are proportional to the diameter of the tube, whilst the weight of the water is proportional to this diameter squared - hence a smaller diameter favours the adhesive forces.

      Something funky to try is to split the stem and put one half in blue and the other in red. You can get multi-coloured flowers.

      Tuesday, 6 January 2015

      Ep 156: Science for kids - home-made lava-lamp

      This Christmas break, I have been mucking around with science experiments for my kids. Here is the first of a few easy experiments you can try at home.

      The following videos show you how to make a home-made lava lamp. It is very simple - grab a clear cup (or bottle or vase or flask), fill it about a third full of water and two thirds full of oil. The oil floats on the water as it has a lower density. Add some food colouring (you can do this at the start directly to the water, or after you have added the oil - this has the added benefit of showing that the food colouring does not dissolve in the oil, so it drops through the lower density oil to the water below).

      You may already have Alka Seltzer in your medicine cabinet - it is an over-the-counter pain reliever containing Citric acid and Sodium bicarbonate (also known as baking soda). Split the alka seltzer tablets into about 4 bits, and add them to make your lamp. See the videos below for what happens.

      Shorter version:

      Longer version:

      The reaction that is occurring is:

      Citric Acid + Sodium bicarbonate → Sodium citrate + Carbon dioxide + Water
      C6H8O7 + 3NaHCO3 → Na3C6H5O7 + 3CO2 + 3H2O

      Or more simply:
      3H++ 3HCO3-  → 3CO2 + 3H2O

      Note, if you don't have alka seltzer, you can try baking soda, but add some vinegar to the original water mix, as vinegar is acidic and provides the H+.

      When you add the alka seltzer to the water, the citric acid and sodium bicarbonate start to dissolve, which allows the reaction to start and is why they don't react in solid form in the tablet.

      The reaction produces gaseous carbon dioxide, which has a lower density than both water and oil, and hence rises through the layers. When the gas bubbles exit the water into the oil, they trap and pull up a small amount of water with them. When the bubbles reach the surface, they burst and the water falls back through the oil. It's worth looking at this closely, as you will observe coloured water droplets that don't have quite enough CO2 stuck to, or dissolved within, them to make it all the way to the surface, and so they float around, buffeted from side to side by other, more vigorously moving, droplets.

      Here's some more over at CSIRO.

      Friday, 7 November 2014

      This is how you do optimisation

      Press Release: Kellyville Ridge Man scores a perfect 15 in Opal

      Kellyville Ridge NSW. Local resident Tim Surendonk is celebrating today after scoring the coveted perfect 15 in Opal. As Tim explains it, a perfect 15 occurs when a user of the Opal card pays the absolute minimum amount for unrestricted travel for 6 days in a week (Tuesday-Sunday).

      The Opal rules allow unlimited travel after reaching 8 paid journeys, something which the average commuter will only attain after 4 days of to-work-and-back travel. You may think that this would be easy to do--just take 8 consecutive paid trips on trains, ferries or buses--but Opal rules make it difficult. Each trip must be separated by at least 60 minutes in order to qualify as a separate journey, and the day's paid journeys max out after $15 of expenditure--any trips after that aren't "paid-for" and so do not count towards the 8 trips.

      Mr Surendonk managed his perfect 15 after carefully taking 8 minimum bus trips, each separated by at least an hour, paying $2.10 for the first 7 and 30c for that last trip.

      "It wasn't easy", Mr Surendonk said. "I pretty much had to devote a whole day of annual leave to achieve it, but I did get to go to the Doctor and return some library books" he admitted.

      To celebrate, Mr Surendonk took his kids down to Wollongong on Tuesday for a holiday outing. "I had to pay for them, but my trip was free! Thank you Gladys Berejiklian".


      Mr. Surendonk's Opal Statement.

      Thanks to Tim, PhD in logic, for writing his own press release! I work with some great folk. Tim did end up getting a letter from the minister congratulating him. More in the Rouse Hill Times.

      Sunday, 13 July 2014

      Ep 155: Fact or Fiction with ANSTO



      The Australian Nuclear Science and Technology Organisation undertakes research and development in nuclear science and technology. This has wide application including nuclear medicine, atmospheric monitoring, materials engineering, neutron scattering and climate change research.

      ANSTO is also very active in science communication, and one of their major community engagement projects is Fact or Fiction, a 90 minute show where the audience watch clips of classic sci-fi hits before voting on whether the technology featured is actual science fact or pure science fiction. Once the audience voting has been conducted, an ANSTO scientist critiques the science featured in the film. They have also run a Fact or Fiction Survey, the results of which are illustrative of the general public understanding of science in everyday life. Another effort ANSTO is conducting is Neural Knitworks, where knitted neurons join together to create a textile brain installation.

      I spoke with Rod Dowler from ANSTO's Discovery Centre about their science communication efforts, and in particular, Fact or Fiction. Listen to this show here:



      In the podcast, we mentioned a song about hoverboards. I would have loved to have put it in the show, but that wouldn't be legal. So if you'd like to hear it, stream it  below or buy it from iTunes right here:





      Songs in the podcast:

      Friday, 20 June 2014

      ABC Radio - June - Mars One

      I've been doing quite a bit of regular radio with the ABC recently (ABC Riverina and ABC Central West), so I thought it would be a good idea to put up a post each month on what we've spoken about.

      The main topic this month was the Mars One project, which plans to establish a permanent human settlement on Mars. This is an incredibly optimistic project, made even more interesting by the fact that it is going to be funded by a reality TV show, which will track the training and lives of the astronauts, and presumably follow them into space. A number of Australians are still in the running to be part of the final four who make it.



      There are seemingly innumerable ethical issues with this project, notwithstanding the fact that at $6 Billion, it seems unbelievably cheaper than NASA estimates (~$100 Billion) for similar projects. Check out the company's FAQs - they have addressed a number of questions that immediately come to mind (food, air, fuel etc). The one outstanding question for me is - what if it goes wrong? Does the company abandon the astronauts on Mars? Does NASA have an obligation to go back to get them? What if everyone stops watching the reality TV show? I watched (well, glanced at) Big Brother One but can't tell you a lot about the following umpteen seasons...

      One thing we do know is that long distance space travel is no place for extroverts. Unsurprisingly, a NASA-funded study has found that extroverts will probably drive their space companions bananas if kept in confirmed quarters for too long.