Obviously, I very strongly disagreed with this report.

I’ve already blogged about the numerous logical fallacies I found in that report, so I won’t go over those points again. Instead, I’ll start my counter argument by stating this:

It does not matter if the LHC finds nothing.

And it does not matter if we can’t use a quark to make our cars go faster.

It really doesn’t.

If the LHC does find the Higgs Boson, it doesn’t matter if we can’t make better toasters with it.

Let me explain.

Scientists, in any field, typically research stuff that they are interested in. And they are passionate about that research. It’s what drives them to do long hours for rubbish pay. And if the technology to reach their goals doesn’t exist, they invent it. They create it. They develop it.

Now, it may turn out that their research goals have practical applications. It may not. But, perhaps more importantly, it may turn out that the technology and methods developed towards their goals can be used elsewhere. You just don’t know. Unexpected applications, by their very definition, are unexpected. And it does not matter if the goal is achieved or not. I need to stress the importance of this point. It really doesn’t matter if the goal isn’t achieved – the technology has still been invented. And the pure scientific knowledge has still been gained.

When I interviewed the 2011 Physics Nobel Laureate Brian Schmidt (episode 107 of  The Pod Delusion - there is also a transcript of the interview on this blog), he gave a fantastic example. An astronomer called John O’Sullivan was studying Black Holes. He was looking for Hawking Radiation – the mechanism by which Black Holes are hypothesised to evaporate.

Sounds stupid and pointless doesn’t it? What a complete waste of money! What possible use would that be?

Well, the techniques invented by that astronomer are now used all over the world. That device probably somewhere near you right now uses his invention. John O’Sullivan really wanted to find Hawking Radiation. He didn’t. But, along the way, he invented WiFi. And that patent has made millions. It really didn’t matter that he didn’t find Hawking Radiation and give Stephen Hawking his Nobel Prize in Physics. Actually, perhaps Stephen Hawking wouldn’t agree with me on that point…

What about an example from mathematics? A few decades ago, mathematicians were studying huge prime numbers. Another seemingly pointless activity. Now that research protects our bank transactions on the Internet. Another example of an unexpected application.

OK, that’s maths and astrophysics. But what about particle physics? The original criticism was about high energy particle physics, so I’d better give some examples from this area. And I’m not going to give the standard “The World Wide Web was invented at CERN” example.

A quick Google search reveals that there are 26,000 particle accelerators in the world today. Only 1% of these are physics research “toys”. The biggest use for accelerators is in medicine. For example, beams of accelerated nuclei are used in the treatment of cancer. This is called Proton Therapy. I don’t know about you, but I’m quite happy for this technology to be researched and perfected by scientists at places like CERN and Fermilab.

There are also spin off applications for particle detector technology. PET (Positron emission tomography) and MRI (Magnetic resonance imaging) scanners can now be found in hospitals all over the world. Both very useful inventions. Well, CERN scientists played an important role in the development of PET scanners, building prototypes with the hospital in Geneva. And that wasn’t a one off, it’s still happening today. With their newly discovered knowledge of particles, magnets and semiconductors, technology developed specifically for particle accelerators at CERN is currently being used to develop combined PET/MRI scanners. Yes, apparently, CERN scientists actually know how magnets work.

By the way, the ‘P’ in PET stands for positron. An anti-electron. Who would have predicted that antimatter particles would have a medical use? I’m pretty sure that Paul Dirac, the physicist who predicted the existence of antimatter in the 1920s, wasn’t thinking about medical equipment. He was just doing pure particle physics research. Nearly a century later, what sort of economic value can we now attach to this research?

In his book Demon Haunted World, Carl Sagan explains how curiosity-driven research has led to huge civilisation advances:

Maxwell wasn’t thinking of radio, radar and television when he first scratched out the fundamental equations of electromagnetism; Newton wasn’t dreaming of space flight or communications satellites when he first understood the motion of the Moon; Roentgen wasn’t contemplating medical diagnosis when he investigated a penetrating radiation so mysterious he called it  ’X-rays’; Curie wasn’t thinking of cancer therapy when she painstakingly extracted minute amounts of radium from tons of pitchblende; Fleming wasn’t planning on saving the lives of millions with antibiotics when he noticed a circle free of bacteria around a growth of mould; Watson and Crick weren’t imagining the cure of genetic diseases when they puzzled over the X-ray diffractometry of  DNA; Rowland and Molina weren’t planning to implicate CFCs in ozone depletion when they began studying the role of halogens in stratospheric photochemistry.

From these examples and more we know that the discovery of unexpected practical applications of scientific exploration does happen. It would be highly presumptuous and, in fact, an argument from ignorance to say that this time nothing practical is ever likely to come of it, just because such an application lies outside the bounds of our imagination.

And even if discovering the structure of matter doesn’t payoff, the technology developed for the LHC to allow physicists to understand the structure of matter has already started to pay off. The number of spin-offs continue to grow. For example, superconducting magnets and cables developed specifically for high energy physics at the LHC are now being developed commercially for power transmission. This will offer huge gains in energy efficiency and make the world a greener place.

I’m going to by mentioning the inspiration and wonder that has been provided by the LHC. The LHC is this generation’s Apollo programme. It’s that important. It’s that inspirational.  The story of the LHC has captured the imagination of the public, even if the majority don’t know exactly what it is doing! Something about it keeps it in the news.

And hopefully it will inspire school kids today to become the next generation of scientists who want to take part in discovering the fundamental laws of the Universe, or perhaps, they’ll go on to cure cancer.

I recorded this as a report for episode 118 of the Pod Delusion.

Special thanks to Peter Silk for help with this report. Some of the phrases used above are form his emails and Instant Messages to me!

And also a thank you to George Hrab for beautifully reading out the Carl Sagan quote for the report.

Related posts

Hunting for Logical Fallacies in a Pod Delusion report.

The “Economic False Dilemma” logical fallacy.

“I don’t think that any practical use has come of any particle physics discoveries made in the last 50 years” and corresponding Reddit discussion.

I obviously strongly disagree with this.

However, note that the key word in his sentence is “discoveries”.

Now, I know that there are plenty of practical uses that have emerged from particle physics over the last 50 years (WWW, PET, MRI, surperconductors in power transmission, cancer therapy, etc, etc). In fact, that was the basis of my response post explaining the value of blue sky research in terms of spin-offs and unexpected inventions.

But the “rules of engagement” appear to be this: has there been any application of the newly gained knowledge of the structure of matter? Rather than the obvious spin-off usages for the tools used to probe the structure.

So, for example, particle accelerators are used to treat cancer (Proton Therapy). But this wouldn’t count as an example as the particle accelerator was developed as a tool to “play with particles”.

Basically, I want to know if we have built anything by knowing more about atoms than just protons, neutrons and electrons.

Examples:

• Has the knowledge that, say, a proton is made from two up quarks and one down quark been useful in the invention of something?
• Has the knowledge that, say, an up quark has a charge +²⁄₃ e proved useful?
• The Tau particle was detected in the 1970s. Has there been any practical application of this knowledge since?

I’d suggest that it is a ridiculous rule to disallow the technology spin-offs in the first place. Those technologies were definitely invented as a direct result of scientists wanting to probe matter, and that, for me, is the important point. 

What do you think?

Related posts:

The Value of Curiosity Driven Research (my response argument to the original report).

In summary, last week, Adam submitted a Pod Delusion report critical of the funding of particle physics. I spotted a number of Logical Fallacies in that report (and in the comments about the report) and blogged about them.

Adam’s excellent suggestion (it’s well worth reading this comment) was that we discuss the points one by one.

His first response is regarding a False Dilemma logical fallacy, which, in the report, went something like:

1. Either we can fund particle physics, or we can fund other, useful stuff.
2. We must fund the other, useful stuff
3. So, we can’t fund the particle physics.

OK, here goes then. Let’s start with the “economic false dilemma” fallacy.

You make a perfectly reasonable point, which is that if we stopped spending money on the LHC, it wouldn’t necessarily get spent on one of the examples I’ve given as being more worthy. It might get spent on something like bigger duck houses for MPs. However, what I’m arguing is that we stop spending money on the LHC and spend it on something more worthy, not simply that we stop spending money on the LHC and then hope for the best. So I don’t think that point invalidates my argument.

What is true, however, is that every pound we spend on the LHC is one pound less that we have to spend on other things. So, on the assumption that the total pot of money for doing sciencey things is constant (and of course that is an assumption, as it would also be possible to increase the total pot, which I suspect we’d both welcome, although I don’t think it’s likely to happen in real life any time soon), funding the LHC means less money for other sciencey things.

Where I think I did fall down a bit in my piece (and if you’ve been following the discussion on the PD website you’ll see that Quackonomics picked me up on this) is that I failed to make a clear distinction between spending money on research and spending money on other worthy things that don’t need any research, merely putting resources behind some existing knowledge. An example of the latter would be polio eradication. We already know how to do it, so no research is needed. We just need to get out there and vaccinate all those troublesome little disease hot spots.

So, it might be a reasonable assumption that money not spent on the LHC could be spent on other kinds of research (eg developing a malaria vaccine), but it’s probably less reasonable to assume it will be spent on non-research things like eradicating polio, because that would put it into a completely different budget.

Nonetheless, if we think of the LHC as part of total government spending, then there is no real reason why any money not spent on it couldn’t be put into anything else we like, which might include polio eradication.

So, in summary, I don’t think I’m guilty of a logical fallacy here. I would be if I were saying “let’s just stop spending money on the LHC and see what happens”, but that’s not the argument I’m making.

Over to you…

So, as Adam requests…over to you.

A fallacy is incorrect argumentation in logic and rhetoric resulting in a lack of validity, or more generally, a lack of soundness.

In laypersons terms: you know when you hear an argument and it doesn’t sound quite right? There is something in the argument that you can’t put your finger on but sounds wrong? Well, there are names for all those sorts of arguments.

There are loads of free resources out there: PDFs, eBooks, etc. I highly recommend the free Hunting Humbug eBook.

As well as being a skeptic, I’m also a keen “pretend physicist” – basically, I’m studying all the astrophysics related course I can find at the Open University. I regularly contribute to the excellent crowd-sourced Pod Delusion podcast – a podcast about interesting things. I normally send in physics and astronomy related reports and interviews. My personal highlight was interviewing the 2011 Nobel Prize in Physics winner, Brian Schmidt, for episode 107.

So, when I heard a report on episode 117 that argued that high energy particle physics did not make economic sense, I bristled. And I also spotted several logical fallacies both in the audio report and then further in the online comments about the report.

So, I thought I’d try to use my new found logical fallacy skills and apply them to the report and the comments. I’ll split the report and comments into various sections and discuss what I think the logical fallacy is. I’ve never done this before so feel free to correct my mistakes!

An Economic False Dilemma

This was a throw away comment during the audio report. I responded with a comment on the website:

CERN gets it’s electricity from French nuclear power, so you could argue it’s quite green.

The response:

The argument about being powered by nuclear and therefore being green doesn’t really stack up, because if CERN wasn’t using the energy from the nuclear plants, something else that’s currently using fossil fuels could use it instead.

WTF!?

The audio report included this line:

Maybe physicists could work on getting computers to work. Hands up if your computer crashed this week.

Neil Denny, the host of the excellent Little Atoms podcast and radio show (broadcast on Resonance FM), reads a lot of books.

The other day he tweeted:

“Short of gift ideas for Christmas? I’m going to tweet a list of my 10 favorite books that we’ve covered on @littleatoms this year.

A caveat, I only book people who I like and who’s books I want to read, that’s a strict policy, so everyone who comes on the show is great!”

But anyway, in a whole year there’s got to be some favorites, so here they are. In order of appearance on the show, not order of preference.”

As Neil doesn’t have a blog, I volunteered to host his book list.

Written in Stone by Brian Switek: ”The hidden secrets of fossils and the story of life on Earth.”

The Way of the Panda by Henry Nicholls: “The extraordinary impact of the panda – from obscurity to fame – a story of China’s transition from shy beginnings to centre stage.”

The Psychopath Test by Jon Ronson: ”From the author of Them and The Men Who Stare at Goats, a book exploring the psychopath . . .”

The Revolution Will be Digitised by Heather Brooke: ”Timely and gripping Investigation of how the internet is transforming politics by award-winning journalist Heather Brooke.”

33 Revolutions Per Minute by Dorian Lynskey: ”An astounding history of protest music, told through 33 momentous songs.”

Incognito by David Eagleman: ”Taking in brain damage, plane spotting, dating, drugs, beauty, infidelity, synaesthesia, criminal law, artificial intelligence and visual illusions, Incognito is a thrilling subsurface exploration of the mind and all its contradictions.”

Red Plenty by Francis Spufford: ”What if the Soviet ‘miracle’ had worked, and the communists had discovered the secret to prosperity, progress and happiness…?”

Geek Nation by Angela Saini: ”Through witty first-hand reportage and penetrative analysis, Geek Nation explains what this means for the rest of the world, and how a spiritual nation squares its soul with hard rationality. Full of curious, colourful characters and gripping stories, it describes India through its people – a nation of geeks.”

Free Radicals by Michael Brooks: ”Scientists present themselves as cool, logical and level-headed, but the truth is they will do anything: take drugs, steal, lie and even cheat – in the pursuit of new discoveries.”

The Etymologicon by Mark Forsyth: ”The Etymologicon springs from Mark Forsyth’s Inky Fool blog on the strange connections between words. It’s an occasionally ribald, frequently witty and unerringly erudite guided tour of the secret labyrinth that lurks beneath the English language, taking in monks and monkeys, film buffs and buffaloes, and explaining precisely what the Rolling Stones have to do with gardening.”

Brian Schmidt - 2011 Nobel Prize in Physics, Joint Winner (image by Belinda Pratten)

Brian Schmidt of the Australian National University in Canberra was recently named as a joint winner of the 2011 Nobel Prize in Physics. The formal citation reads:

“For the discovery of the accelerating expansion of the Universe through observations of distant supernovae”.

Brian and his team’s work on the expansion of the Universe fundamentally changed astrophysics – it opened up a whole new area of science and introduced the world to the concept of Dark Energy.

Brian kindly agreed for me to call him to chat about the award and the science behind it. An edited 10 minute version of the interview is available on episode 107 of The Pod Delusion. The full 20 minute version is available on this page too.

Kash Farooq: Let’s start at beginning. You moved from the US to Australia in 1994 and made the discovery in 1998. Can you briefly explain what you and your team discovered, and how you discovered it?

Brian Schmidt: I finished my PhD at Harvard in 1993 and I started a post doctorate fellowship at the Harvard-Smithsonian Centre for Astrophysics; I was part of the Smithsonian side rather than the Harvard side. I was looking for something to do and in 1994 Mario Humuy from Chile came up and showed us his new data on supernovae, which showed that you could use them to measure distances very precisely. At the same time Saul Perlmutter who had been trying to discover supernovae for about 6 years and then suddenly found 7 of them.

So, I was going down to observe in Chile in 1994. I had a chat with the group down there and I hatched a plan that we would take on Saul Perlmutter’s team in measuring how fast the Universe was slowing down over time. This was just before I moved to Australia.

I figured that although Saul’s team had been working on this a long time, our team had been working on it from the other side – from the supernovae side. And so it seemed to me to be a reasonable thing to go out and try this experiment.

When I moved to Australia it was really about trying to measure what the Universe did back in time by looking at really distant objects. I really put my heart and soul into it when I got to Australia for three and a half years.

Kash: One of the interesting stories neatly demonstrates how science can work. You were actually expecting the complete opposite of what you found, and this opened up a whole new area of physics. Can you tell me more about that?

Brian: I always like to work on big questions. When I came to Australia I decided I may as well try to answer a big question; the question I was looking to answer was how fast does the Universe slow down, and therefore gauge the future of the Universe.  If the expansion is slowing down a lot then the Universe will reach a maximum size and then gravity will take over and run the Universe in reverse. Just like a ball you throw up in the air, it will crash down and we get the Big Bang in reverse, which we like to call the Gnab Gib!

So that was the big question we were trying to answer.

After about 3 years, the data were coming in. I was talking to Adam Reiss who was spearheading this work (we handed out each part of the project to young people, Adam was one of the young people on the team). He was doing a huge amount of work. The data showed that the expansion of the Universe was not slowing down at all but was speeding up. That was a real crazy thing to be confronted with. It didn’t make a lot of sense. It seemed just impossible. It was a pretty scary time when we first saw that result.

Kash: How many times did you double check, triple check your results before you decided to make the announcement?

Brian: Initially you just start looking for problems, checking and rechecking everything but after a while you’ve done everything you can and nothing is obviously wrong. We opened it up to the team and said “OK guys, we’ve got this crazy result. Any test you want us to do, we’ll test. We think we’ve done everything.”

The group came up with all sorts of things to think about so we went through and worked more. But at some point it slowly sunk in that the universal acceleration we were seeing just wasn’t going to go away.

It took a few months but we’d done everything we could several times, and several people did it and everyone just got the same answer.

Kash: When you made the announcement, just like the recent faster than light neutrinos announcement, what was the reaction around the world? Were scientists skeptical?

Brian: I was expecting a reaction very similar to the faster than light neutrinos announcement, where they’ve gone out as a good team, they’ve gone out and said “Hey we see this” and most of the world says “It’s got to be wrong”.

In our case I was expecting to say this is just wrong and we’ll figure out the problem. Some people were skeptical, and I don’t blame them for being skeptical – I would have been skeptical as well. I was skeptical when we released it – I just could not make the result go away.

There were some problems in cosmology back in 1998 where things did not quite work properly. The accelerating Universe only worked if the Universe was full of energy that was previously unaccounted for, the stuff we call dark energy – what Einstein called the Cosmological Constant.

Now it turns out that this dark energy fixed most of the outstanding problems in cosmology. It wasn’t that this dark energy had been disproved; it was just crazy that somehow we had missed 75% of the Universe. And this 75% of the Universe caused gravity to work in reverse. It just seemed too crazy to believe.

I think for the guys that are measuring the faster than speed of light neutrinos, I commend them for coming out. I have to admit that I suspect there will be something found wrong – but I could be wrong. Maybe the Universe really is crazy and for some reason these neutrinos, which are at very high energy, just travel faster than the other neutrinos that we have measured from supernovae, for example.

Kash: Where did the term “dark energy” come from? Was it just an obvious choice as the term “dark matter” was already in use?

Brian: I believe the term dark energy was invented right here in Canberra, Australia, in ‘98 or ’99 by Mike Turner, a very well known cosmologist, who we invited here to give a cosmology talk right after the acceleration announcement. We had a big conference here. He invented the term for his talk called “Dark Energy”.

It’s “energy” because it is tied to space. It’s “dark” because we can’t see it. When astronomers discover something they can’t see, we just call it “dark x”; in this case x was energy.

It was a term that sounded good and made sense as it fit in with dark matter and describes what’s going on.

Kash: What does the acceleration mean for the distant future of the Universe?

Brian: Right now, when light travels through the cosmos to us it has to compete with the expansion of the Universe to get to us. Light takes a long time to get to us, but it gets to us.

In the future because the Universe is speeding up, it is expanding faster and faster over time, at some point galaxies we can see now, the Universe will be stretched so much between us and those galaxies that the light will never reach us.

If you take this to further and further in the future it turns out that the entire Universe that is not gravitationally bound to us right now will eventually be stretched beyond our ability to see it. We will look out to a Universe on which you cannot do cosmology because there is nothing to see. It will be a very empty Universe.

The part of the Universe we are part of will all collapse down into a giant super galaxy and the stars in the super galaxy will slowly use up their nuclear fuel and turn into little stellar embers that just fade into oblivion.

It will be a very cold lonely Universe in the future.

Kash: What does the award mean for Australian science? How has the public and media reacted?

Brian: It’s been really positive. Australia hasn’t had a Nobel Prize in Physics since 1915 for Bragg Scattering – a very important discovery. It’s been a long time between drinks.

Australia spends a lot of effort on science and has a really good university system here. But I think the excitement of a Nobel Prize really has captured everyone. I’ve got to meet with members of both parties; the prime minister; the finance minister. Everyone is really excited. Even what I would describe as the “shock jocks” on radio, have been universally really excited it.

It has really been incredibly positive and I think it has caused the country, as best as I can tell, to reflect on why science is important. And that’s what is really important to me. I want people to understand that the county’s future prosperity fully depends on educating people and getting scientists to go and be able to do things that invents new technologies and that’s where the prosperity is going to come from.

Kash: Do you think the award will help funding?

Brian: Australia is in an interesting situation right now. There is quite a healthy economy; politicians like to say that we are in a dire situation, but the reality is that we are in a very good situation.

We could certainly do better on our funding. Our research grant programme is underfunded a lot by international standards, even by British standards, which I know have taken a huge hit over the last few years.

There are a lot of things we do fund well. We fund our major infrastructure very well. Australia is keen to bring the Square Kilometre Array to Australia; we think we have a superb place to do this next generation radio telescope and the government is spending lots of money on that.

There is also a giant new telescope that I am helping with in the optical regime called the Giant Magellan Telescope.

So the funding situation is a little hit and miss, but I think it’s pretty good.

What I’m hoping I can bring is to emphasise the importance of continuity. One problem we have in Australia is that each government has a set of new ideas and the whole landscape changes with the changing government. As a scientist working on a 5 to 10 year horizon that changing landscape makes it very hard to plan.

We don’t have to spend that much more money but we just need to spend it really smartly. If we do that then science in this country will flourish.

Kash: How do answer the typical question from a politician – how will your research make money?

Brian: We had a science awards dinner the other night where I gave a speech. The Australian Scientist of the Year was the person who invented the techniques with polymers that Australia uses to make our money. I pointed out to everyone “Gosh, I try to worry about how to make money with my discoveries and this man truly took the most direct route for making money with his discovery!” You never know how your discovery is going to work out.

One of my colleagues, John O’Sullivan, was a radio astronomer who in the 1970s was looking for evaporating Black Holes, as predicted by Stephen Hawking. He never found them but what he did realise was that he was having to correct the way radio waves travel in many different directions to the Earth through space – what he called multipath propagation. He realised that this was the same problem we were having doing high speed radio communication – basically he invented Wi-Fi. He was responsible for the protocol 802.11. This has made Australia billions of dollars and it is worth hundreds of billions of dollars internationally.

Basic research in astronomy turned into billions of dollars worth of stuff.

Research is funny. If you just invent what you know, you asymptotically approach no change. Basic research provides revolutions.

Society has emerged out of the dark ages because of that basic science and education transferring into the knowledge chain that eventually gives us technology. I try to explain that chain to the government and I think the government gets it. I’m not sure if they believe it, but I think they get it.

Kash: Where do you go from here? What are you currently working on?

Brian: I am in the final stages of putting a new telescope onto the sky called SkyMapper. This is a telescope which is, from Australia, going to survey every square inch of the southern sky to a level 10 million times fainter than you can see with the human eye, 36 times.

SkyMapper is a state-of-the-art automated wide field survey telescope located at Siding Spring Observatory near Coonabarabran, central New South Wales, Australia. (Image - Wikimedia Commons)

This map of the sky will catalogue billions and billions of objects. It’s really useful to find very rare objects in the sky that can help us to decipher how things work. For example, it will be able to find if there any Pluto-like objects that have not been discovered in the southern sky – the southern sky has not been looked at very carefully.

It will help us find the most distant objects in the Universe. It will help us find stars that have been thrown out of the central super massive black hole region of the Milky Way. It will help us find stellar fossils left over from just after the Big Bang.

It is going to produce a treasure map that we can use the biggest telescopes that we have now and in the future to go through and do detail studies.

It’s a huge project that is just getting started right now. It will take more than a petabyte of data (1000 terabytes, each terabyte is a 1000 gigabytes).

Kash: I’m going to have to ask you the question that I’m sure everyone has: did you think the phone call was a wind up?

Brian: I have a couple of mischievous graduate students and it occurred to me that it could be a practical joke. But I was incredibly impressed by how good they got the Swedish accent. After a couple of seconds it became pretty clear to me that this was more than just a prank.

Kash: Finally, astrophysics is not your only passion – you are also a winemaker. Judging by the “we have sold out” message on your website, winning a Nobel Prize is good for wine sales!

Brian: When I moved to Australia I decided that I one of the things I could do that I could not do anywhere else was do something crazy and run a vineyard.

We have 1.1 hectare Pinot Noir vineyard. It is my therapy to make sure that astronomy doesn’t take over my life.

Maipenrai Vineyard and Winery

Things we slow at first but about a year ago I started getting it right and have been selling well. I was down to four cases when the Nobel Prize announcement went out. Those four cases sold literally within 60 seconds after the announcement.

It’s certainly a great marketing tool, which I’ve been recommending to all my fellow winemakers!

Kash: Which is easier? Astrophysics or winemaking?

Brian: They are very different and they are similar.

With astrophysics, I try to do everything perfectly. I don’t like making mistakes Winemaking is all about making mistakes. Where I try to be pretty much perfect all the time in my astronomy, in my winemaking I know I’ll never be perfect. So in some sense I think, as you can never achieve perfection in wine making, therefore it’s the harder thing to do but it does require a slightly different set of skills.

Related links

My Telegraph article – Dark energy: the universe is destined to become a very cold and lonely place.

My 21st Floor article - Ben Still Interview: Faster than Light Neutrinos.

This was the discovery that led to the introduction of the concept of dark energy – a placeholder phrase used to label the something out there in the Universe that is making space expand faster and faster; the expansion of the Universe is not slowing down, dark energy is causing it to accelerate.

The Nobel Prize laureates used Type Ia supernova to make their discovery.

So, what is a Type Ia supernova?

Supernova 1994D - visible as the bright spot in the bottom left of this image. It occurred in the outskirts of galaxy NGC 4526. Image credit: High-Z Supernova Search Team, HST, NASA

Supernovae are exploding stars. What remains after the star explodes is pretty spectacular too:

Supernova remnant SNR 0509-67.5: image created by combining data from the Hubble Space Telescope composited with X-ray energies from the Chandra X-ray Observatory. Image credit: Credits: X-ray: NASA/CXC/SAO/J.Hughes et al, Optical: NASA/ESA/Hubble Heritage Team

Supernovae are split up into types depending on what we can see in the light they emit. We can determine the elements that the light travelled through on its way to Earth using a technique called spectroscopy; we look at the spectrum created from the light. For an introduction to spectroscopy, see my “Why is the Orion Nebula red?” blog post.

The spectra from Type Ia supernova lack hydrogen. This is significant as stars use hydrogen as their primary fuel source. If a supernova spectrum contains no hydrogen then we know that the star has completely used up all this fuel. And a type of star that fits the bill is a white dwarf star.

A white dwarf star is the remnant core of a Sun-like star that has used up all its fuel, and is mostly made up of oxygen and carbon. They are incredibly dense – packing a mass comparable to the mass of the Sun into the volume the size of the Earth. They exist in a state of equilibrium with the effects of gravity balanced against internal pressure (more specifically, electron degeneracy pressure prevents the white dwarf from getting any smaller).

So, if white dwarf stars are in this happy state of equilibrium, what makes them explode?

In 1930, the astrophysicist Subrahmanyan Chandrasekhar calculated that a white dwarf had an upper mass limit of 1.38 M_Sun. If a white dwarf gained mass to take it over this limit of 1.38 solar masses, the effects of gravity would no longer be supported by internal pressure. The star would collapse and then explode when it hit the next pressure barrier. This mass limit is known as the Chandrasekhar limit.

One proposed method of how a white dwarf can gain the extra mass is accretion from a binary partner. The white dwarf siphons off material from its binary companion.

An artist's impression of a binary star system. A white dwarf star gains material from a companion red giant star. If the white dwarf's mass exceeds 1.38 solar masses, it will collapse and explode as a Type 1a supernova. Image credit: NASA/CXC/M.Weiss

And this is what makes Type Ia supernovae important to us as a tool for measuring distance. If Type Ia supernovae are exploding white dwarfs, then we know that the star had a mass of just over 1.38 M_Sun when it exploded. And that means wherever they explode in the Universe, they always have the same intrinsic luminosity – they always give out the same amount of light. Because of this, Type Ia supernova are known as standard candles; we know how bright they are and so can use them to determine how far away “stuff” in the Universe is. From our location in the Solar System we can use the fact that we know the starting brightness, and how bright/faint they appear to us in the night sky, to work out how far away they actually are. And hence, we can also use them to work out how far away the galaxy that hosted the white dwarf is.

The problems

There are some issues with assuming that the progenitors of all Type Ia supernovas are white dwarf stars that have just tipped over the Chandrasekhar limit. No white dwarfs in an appropriate binary configuration such that they will accrete material in a reasonable amount of time have ever been discovered. There is also a competing mechanism whereby binary white dwarfs spiral into each other – hence the resultant explosion would be from a mass much higher than 1.38 solar masses.

These two issues mean that we may be using Type Ia supernovae as standard candles when they are in fact not suitable. We could be over and under estimating distances.

Related Posts

Two excellent blog posts for some further reading:

• For more information about the issues surrounding the use of Type Ia supernovas as standard candles, I recommend Matt Burleigh‘s blog post: Nobel prizes, dark energy, and the unsolved problem of SNIa.
• For more information on dark energy, I recommend Matthew Francis‘ blog post: 2011 Nobel Prize in Physics: Discovery of Dark Energy.

Asteroid Apophis (the moving dot in the middle)

Its full designation is 99942 Apophis. It is about 270 metres in width and has a mass of 2.7×10¹⁰ kg.

Annoyingly, its orbit around the Sun crosses Earth’s orbit:

Apophis and Earth orbits - the line in red is the orbit of Apophis.

It rose to prominence after initial observations in 2004; it was calculated to have a 2.7% chance of hitting Earth in 2029. Improved observations and data eliminated the possibility of impact in 2029, but there remained a possibility that Apophis would pass through a gravitational keyhole, which would then set up a future rendezvous date on April 13, 2036.

A gravitational keyhole (also known as a resonance keyhole) is a small region near a planet that could alter the course of a passing asteroid, and setup a collision with the planet on the asteroid’s next orbital pass.

Additional data reduced the collision probability further. The probability of an impact on 13^th April 2036 impact is now considered to be 1 in 250,000.

You can interactively view NASA’s data on near-Earth objects at the Jet Propulsion Labs Small-Body Browser. Simply search for the object you want to look at – in this case Apophis – and then click the “Orbit Diagram” link. Then select a date (I entered 1 Jan 2029), zoom in a bit and hit the >> button. You then see the orbits of the planets and the asteroid played out. You can centre on a planet or the Sun. You can also pause at any time and click “Save Image”. Here is what I got for 8^th March 2029:

2029-03-08 - Asteroid Apophis approaches...

And here is what I got a few weeks later – 13^th April 2029.

2029-04-13 - Asteroid Apophis is a little too close for comfort!

Blimey! That’s a bit close. And if having an orbit that crosses Earth’s isn’t annoying enough, 13^th April 2029 is a Friday. Which just adds to the WORLD IS GOING TO END hysteria.

Now let’s look at the current predictions:

[The above table is adapted from JPL's 99942 Apophis Earth Impact Risk Summary. I'm unsure why they have two entries for 2068. Perhaps an old calculation that wasn't deleted when updated data was obtained?]

As you can see, the impact probability is pretty low.

The Palermo Technical Impact Hazard Scale enables near-Earth object scientists to categorize potential impacts. Values of less than -2 indicate no likely consequences. All the values in the above table are less than -2.

The Torino Impact Hazard Scale ranges from 0 (No Hazard) to 10 (Certain). Again, the value for each date in the table above is zero.

The description for Torino value 10 is a little scary:

A collision is certain, capable of causing global climatic catastrophe that may threaten the future of civilization as we know it, whether impacting land or ocean. Such events occur on average once per 100,000 years, or less often.

And on that cheery note, I’ll end this post with what a Torino 10 event might look like:

What a Torino 10 massive impact might look like...

All images from Wikimedia Commons and NASA.gov.

The discoveries were made using an instrument called HARPS – the High Accuracy Radial Velocity Planet Searcher – which is permanently stationed in the 3.6 metre telescope at La Silla in the Andes Mountains.

Montage of the HARPS spectrograph and the 3.6m telescope at La Silla. The upper left shows the dome of the telescope, while the upper right illustrates the telescope itself. The HARPS spectrograph is shown in the lower image.

HARPS detects planets using the radial velocity method. As a planet orbits a star, just as the star’s gravity affects the planet, the planet’s gravity also tugs on the star. This makes the star wobble. By splitting the light from the star into a spectrum, we can measure the size of the wobble as the planet orbits. From the size of this wobble we can calculate the mass of the planet. We don’t actually see the planet; we just detect its presence from this wobble. The formal name for this technique is Doppler spectroscopy.

Using this information, 16 of the 50 planets have been classified as super-Earths. A super-Earth is defined by its mass and it is generally agreed that any planet between 1 and 10 times the mass of Earth is referred to as a super-Earth. Planets above 10 Earth masses are termed giant planets.

One of the super-Earths, which has designation HD 85512 b, was announced to have a mass of just 3.6 times the mass of the Earth. For comparison, Neptune is 17 times the mass of the Earth.

So 3.6 times the mass of Earth is quite low.

The location of this planet is also favourable. It is located at the edge of the habitable zone – this is a narrow zone around a star in which water may be present in liquid form if the conditions are right. From our current sample size of 1, we know that water is essential for life.

This is all very exciting news.

But now it’s time for me to add a little skepticism.

The radial velocity method of planet detection can only provide us with a minimum mass. It all depends on the angle of a planet’s orbit from our line of sight. Different angles will produce different amounts of measurable wobble from our point of view, and hence give different mass calculations. The actual mass of this planet could be 2-3 times more than the announced minimum.

A planet orbiting a star and from our line-of-sight, the orbit is edge on; Doppler spectroscopy will give an exact value of the planet's mass.

A planet orbiting a star and from our line-of-sight, the orbit is at 90 degrees; Doppler spectroscopy method will not detect the planet at all.

Any angle between the two examples above will give different mass measurements. The lowest mass measurement, if we could detect the wobble at all at such an angle, would be at an angle of 89° to our line of sight. The most accurate would be if the orbit was edge on to our line of sight.

So, as you can see, because we have no idea about the angle of the orbit, 3.6 times the mass of Earth is a minimum measurement. If we are viewing this star-planet system at an angle of, say, 50°, the true mass of the planet will be more than 3.6 times.

Apart from its minimum mass and location, we don’t know anything else about this planet. We don’t know its radius. We don’t know if it has an atmosphere. To determine these sorts of properties we need to use a technique known as the transit method, with which we detect a planet passing in front of its star.

We don’t even know if this planet has a rocky surface. Again, from our sample size of 1, there are no planets in the Solar System that are rocky and have a mass 3.6 times that of Earth. In fact, there are no rocky planets in the Solar System with a mass more than 1 times that of Earth! Basically, there is only Earth! We don’t actually know yet where the boundary lies between rocky planets and gas giants.

It is possible that this planet is huge, with a mass of, say, 5 times that of Earth. This would mean it had a low density, and hence must be gaseous rather than rocky.

As the tools available to astronomers have improved, more and more exoplanets have been discovered. The rate of discovery is accelerating. UK scientists are also heavily involved in the Kepler mission, which uses the transit technique of planet detection.

Kepler spacecraft was designed to discover Earth-like planets orbiting other stars.

The Kepler mission recently announced 1235 candidate planets. This included 68 candidates of Earth-like size and 54 candidates in the habitable zone of their star.

Kepler candidates planets as of February 2011

I’m pretty sure it won’t be long before astronomers will detect a planet similar to Earth – in terms of mass, size and atmosphere. In the meantime there will be many false alarms. There is a European Space Agency proposal to build a much larger version of Kepler, called Plato. It is currently at an advanced stage of planning and selection. If approved, it will launch in 2018 and even more planets, and hopefully confirmed Earth-like planets, will be discovered.

I was going to cover the recently launched Juno spacecraft – a 5 year mission to Jupiter. But the NASA website is lacking in technical details about this at the moment – I guess they were a bit busy preparing to send a spaceship across the Solar System…

Instead, I thought I’d look at Cassini.

Cassini is a spacecraft that is currently orbiting Saturn and sending back stunning, beautiful images of the planet, the rings and the moons.

Saturn imaged from Cassini

In this image you can see the heavily cratered Epimetheus and smog-enshrouded Titan, with Saturn's A and F rings stretching across the scene.

That’s the surface of Titan; the site of the most distance spacecraft landing.

Cassini is named after the Italian astronomer Giovanni Domenico Cassini. He was the first person to observe 4 of Saturn’s moons and also spotted a gap in the rings – the gap is now called the Cassini Division. The data provided by the spacecraft has led to some amazing discoveries.

Cassini also dropped the European Huygens probe onto the surface of the moon Titan – this is the most distant landing of any craft launched from Earth.

But how did Cassini get there? How did it traverse the billions of kilometres of space to get to Saturn and go into orbit around the giant planet?

Well, to start with, it didn’t just go straight there. The Cassini was heavy – over 6 tonnes. Even the most powerful launch rockets today would not have been able to provide the spacecraft with enough speed to escape the pull of the Sun’s gravity to reach Saturn.

Instead, of going straight there, Cassini was sent on a tour of the Solar System to take advantage of a technique first proposed in 1961 called gravity assist.

Cassini passed by Venus twice, and the Earth and Jupiter at such trajectories so that it could use the gravity of each planet to gain some speed. The spacecraft (sort of) bounces off the gravitational field of each planet.

Cassini's Interplanetary trajectory

During a gravity assist, a tiny amount of the momentum that the planet had in their orbit around the Sun is transferred to the spacecraft, increasing the spacecraft’s speed.  So, the planet being used in the gravity assist manoeuvre slows down a little.

And no, NASA isn’t going to make the Earth fall into the Sun and kills us all. The loss of momentum experienced by the planet is vanishingly small.

You can view animated simulations of a gravity assist at the Messenger Education website.

In all Cassini travelled 3.5 billion kilometres to get to Saturn. Next question – how do NASA work out where exactly the spacecraft is?

To work out if the spacecraft is moving towards or away from Earth, Doppler Shift is used. Radio transmissions sent by Cassini are captured by NASA’s Deep Space Network. Depending on whether the radio waves are bunched up or stretched out tells us whether Cassini is moving towards us or away from us.

And to work out how far away the spacecraft is, specially coded signals are sent to the spacecraft which are immediately returned. As the signals travel at the speed of light, the round trip distance can be calculated. The calculations are incredibly precise – they even take account of how long Cassini’s electronics take to turn around the signal and how far Earth has moved around its solar orbit since the signal was sent. The current time taken for the round trip of the signal is about 3 hours.

Around Saturn, optical navigation images are taken of Saturn’s moons against a field of background stars. The positions of the stars are well known and allow NASA to know exactly where Cassini is in the Saturn system and in which direction it is pointing. This information allows NASA to reposition Cassini or re-point the instruments.

The Cassini mission is due to continue until 2017. Eventually the fuel for the thrusters will run out so NASA will no longer be able to change its position. Before that happens they have to decide what they are going to do with it.

Because Saturn is too far away to use solar power, the onboard electronics of Cassini are powered by electricity generated from the heat of nuclear decay; specifically by three Radioisotope Thermoelectric Generators (RTGs).

Jet Propulsion Laboratory workers inspect one of the radioisotope thermoelectric generators on the Cassini spacecraft. RTGs use heat from the natural decay of plutonium to generate electric power. The three RTGs on Cassini will enable the spacecraft to operate far from the Sun where solar power systems are not feasible.

So, what do you do with a spacecraft that has 30-odd kilograms of plutonium and associated decay products on board?

NASA have got about 5 years to work that one out.

I recorded a version of this blog post for episode 99 of The Pod Delusion – a podcast about interesting things.