MRI Scanning the Stars

Professor Alyssa Goodman, Harvard-Smithsonian Center for Astrophysics

Chris - That’s exactly what Professor Alyssa Goodman from Harvard University is doing. She’s taking some of the systems that have been geared up to do better body scans with MRI and applying them  to images of the night sky to enhance those pictures and  she’s with us now. Hello Alyssa. Thank you for joining us. Tell us a bit more about this work.

Alyssa - We have a challenge in astronomy that more and more often we’re able to get a third dimension of data: something like distance, not always exactly distance. Instead of seeing just a flat sky we can see thing where we know what distance. We can see in my work, for instance, gas clouds that are busy forming new stars. We like to see what they look like the way that we could go around 3D clouds in the sky. Of course you can’t do that in astronomy. We need a way of putting the images back together into something that looks more like a 3D picture that turns out that the computer software to do that we need is similar to the software that they use in medical imaging.

Chris - Why is it such a problem, compiling images into three-dimensions like that?

Alyssa - It turns out it’s less of a problem in other fields and in astronomy people are just not used to having that kind of information. They were starting to try to build their own software and then we realised that a lot of other people have faced this ad done a good job of, for example, making animated movies. You may know that Pixar and companies like that have some of the most powerful computers around. It turns out that 3D animations, moving 3D pictures is rather computationally intensive to do high resolution. People in other fields, as I mentioned before – notably medical imaging and in film, movies and Hollywood – had figured that out quite well. We’re trying to borrow on what they  already learned.

Chris - When you start doing this do your images literally come alive? Can you see things that, can you identify details that have previously been overlooked?

Alyssa - One of the things that we’re interested in, in my own work which has to do with star formation, is what the impact of jets of material and expanding shells from stars have on the clouds that the stars are forming in. Imagine terrestrial clouds and you set off a bomb in it and you want to see if the expansion wave, some kind of sphere expanding from that bomb looks like. You’d really love  to be able to see a 3D image of that. When stars set off either supernova explosions of just powerful winds from stars the same kind of thing happens to these clouds that they’re in. It’s very important for us to understand what that looks like. In a lot off cases it’s difficult to see that happening. It’s important to view what happens to these clouds over millions of years as they evolve. This software has let us, among other things, see the outflows and shells that come from these stars in a 3D way that the human brain understands which was very hard to see when looking at just slices of the images before.

Chris - Can researchers begin to speculate that, in fact, our own solar system (in other words, the sun and our clutch of planets) actually get buffeted into existence by a big star nearby that was doing something similar to what you’re describing? It was putting a jet of material out which pushed a cloud of gas to make it fall into itself, which then formed us?

Alyssa - Absolutely. There’s a theory called triggered star formations and the idea is there are these gas clouds out there which are marginally what’s called self-gravitating. They’re sort of held together by their own gravity but not quite. They might blow apart, they might collapse but if you come by and push them a little bit – sort of trigger – then they’re more likely  to collapse quickly and make something like our solar system. One way to do that is having a big blast wave either from one of these outflows or some sort of shell, possibly a supernova come by.

Chris - What are you looking at, at the moment? What’s the prime focus of study?

Alyssa - Right now we have something we’ve been doing over the past five or six years called the COMPLETE Survey of Star-Forming Regions. That’s a long, funny acronym you can look up online. What it does is it looks at some of the nearby star-forming regions using every technique we can use from the ground. Optical wavelength and radio wavelength. Radio is where we can make these three dimensional images. With the Spitzer Space telescope, which is the infrared part of the Hubble telescope, has also looked at these same regions. They’re essentially targeted regions where we essentially want to understand the whole process of star formation. What we’ve been able  to do with this 3D imaging project that we call astronomical medicine is to be able to give people 3D views of what these very large regions of space look like, to be able to  put back together in our minds a picture of what’s going on. From that picture we make hypotheses. Recently our work is about the details of the role of self gravity, how likely little bits of this gas are to collapse over time on themselves and to understand whether our theories are right. The best way to do that is to see a picture of what they mean. We’ve been able to convince people that we think we’re on the right track.

Chris - And you have some spectacular pictures on your own website. If anyone listening on the radio wants to check it out, where’s the web address so they can take a look at those pictures?

Alyssa - The best way to do it is to just type my name: Alyssa Goodman in Google and I think it’s the first link that comes up.

Alyssa's website can be found here, and there are some fantastic pictures, movies, virtual reality objects and even a 3d pdf available on the Harvard IIC Websites.

February 2009

The Post Prandial Proceedings of the Cavendish Society

Dr Jeff Hughes, Manchester University

Jeff - The post-prandial proceedings of the Cavendish Physical Society were a collection of after dinner songs that the research students sang at the annual Cavendish dinner every year.  Some of the students were very good singers so they sang favourite songs of theirs.  Some of them were very good aspiring lyricists and they re-wrote the words to some of the songs to reflect the events and personalities of the Cavendish Laboratory.  They just told stories in their songs about what was going on in the lab.

Ben - This was a student thing.  Was this just a lot of fun by the students and researchers or did some of the more eminent people get involved as well?

Jeff - At the annual dinner the professor would be there, the head of the laboratory.  There would be guests who would have been former students of the laboratory who had gone on to jobs and scientific eminence elsewhere.  They'd be invited back and that would create a very nice sense of tradition and continuity with the past with the current students.  The former laboratory members could be held up as role models for them as to what they might aspire to.

Ben - A very good opportunity to meet some of the era-defining scientists of the time and, at the same time, have quite a lot of fun.

Jeff - Absolutely.  Could you imagine being in a dinner where you would see your head of department and a well-known Nobel prize winner standing on their chairs, linked arms singing Auld Lang Syne at the top of their voices.

Ben - This sounds like a very casual thing.  It happened at a yearly dinner but how do we know about it?  This sort of thing usually would be a bit of an inside joke that would pass by unnoticed.

Jeff - This was a very serious informal tradition.  The students were so pleased with their own songs that they kept them.  In 1904 they published them in a pamphlet and that was republished in six editions up to 1926.  That's how we know about these songs.  We know something from diaries and letters and so on about how they were actually performed.

Ben - Could you give me an example of the sorts of lyrics that they were coming up with?

Jeff - Yeah.  A.A. Robb, the mathematical physicist wrote this one about 1905-06.  It's to a cod Irish jig called Father O'Flynn.  I like this one because I play the fiddle and I play Irish jigs quite a lot.  Imagine an Irish jig rhythm. It's:

Of dons we can offer a charming variety

All the big pots of the Royal Society

Still there is no one of more notoriety

Than our professor, the pride of us all.

Here's to the health of professor JJ

May he hunt lions for many a day

And take observations and work out equations

And find the relations which forces obey.

When the professor has solved a new riddle

Or found a fresh fact he's as fit as a fiddle.

He goes to the tea room and sits in the middle

And jokes about everything under the sun

Then if you try to look grey at his jest

You'll burst off the buttons that fasten your vest

For when he starts chaffing though tea you'll be quaffing

you cannot help laughing along with the rest

Ben - This evening, we've seen some of them performed by the HBS choir, do you think this might be the first time they've been performed in, maybe, 100 years?

Jeff -   As far as I know, this is the first time that these, the three songs we've heard tonight, have been performed since probably the 1930s.

Ben -   So really, it's quite an historic event that we've been involved in?

Jeff -   Absolutely!  Historians of science these days are really interested in re-creating historical experiments, what we've heard tonight is the recreation of historical songs, and I'm, absolutely thrilled.

 

March 2009

The Teslathon - High Voltage Fun!

David Woodroffe, Teslathon

Ben - This week also saw the annual Teslathon, held at the Cambridge Museum of Technology.  The Teslasthon sees enthusiastic amateurs get together to show off their home made tesla coils – high voltage devices based on the same principal as an electric transformer.

A transformer works because a current in one circuit – called the primary, induces a current of a different size in the secondary circuit.  This is how mains electricity is scaled down from the high voltage in power lines into the safer voltage that gets to your house.  I met up with Derek Woodroffe to find out more about what the Teslathon is…

Derek - Teslathon is a group of people who are interested in high voltage electronics, Tesla coils and pretty much anything to do with high voltage, current, static electricity: all sorts of technology-related stuff like that.

Ben - So really anything that can make a nice big spark.

Derek - That’s very much part of it. Some of us try and make the biggest spark possible. Some of us try and do it in more interesting ways. Of course we try and push the modern technology to do something that couldn’t be done 18^th century-wise by Tesla himself.

Ben - How do Tesla coils work? They seem a very simple principle.

Derek - They are a very simple principle. Effectively it’s a standard transformer with a primary and a secondary. What Tesla did was he also introduced resonance so the primary has an associated capacitance. The secondary has an associated capacitance. The two synchronise with each other and form a resonant coupling, very much like a young child pushing somebody on a swing. You can get a very small movement that can be made into a very large movement just by the process of resonant rise or multiplication.

Ben - And this enables you to have huge voltages and this is what gives you these lightning-like forks that seem to be flying across the room behind us.

Derek - That’s right. Some of the coils start at about 240 volts. They quite often cheat and go up to 10,000 volts or so into the primary of the coil. Then, due to resonant rise in the way the Tesla coil is constructed we’ll get 100,000 volts or 200,000 volts from the top. But because it is high frequency AC that means we can then push quite a lot of power into a spark or an arc which will then grow much longer than the 100,000 volts sounds.

Ben - And that’s why they do seem to be reaching out and fingering their way across the room. There are some really huge forks of lightning across here. Is it actually safe?

Derek - No. Is the simple answer. Like most things that are interesting or fun it isn’t safe. You have to be very careful. Most of the people in this room have been doing it for very many years. They know their equipment because they’ve had to build it from scratch. It’s not something you can just go out and buy. There is inherent safety: we all abide by a set of rules for the safe running of these sorts of events. People have to stand back from the equipment. The equipment has to be able to be made safe but obviously there is that inherent danger. Any high voltages, high currents, unpredictable equipment you’ve got to view with a degree of distrust.

Ben - I’d imagine that the element of distrust you have means you have to be fairly reserved in public. The people who come along to the Teslathon this weekend won’t really see the full power of what your devices can do.

Derek - They will see a limited amount. There are some things certainly that we wouldn’t do in a public environment that we would do in private. Obviously there’s the safety of the public and the people who are watching the Tesla coils here today is absolutely paramount. We don’t want to hurt anybody. It would really ruin the enjoyment of the whole event for everybody.

Ben - Cambridge Industrial Museum, where we are today, seems like a very appropriate setting for this. I understand you come back each year to do another Teslathon here. Does it feel like home?

Derek - Certainly for me. I’ve been doing this for about seven years now and the actual Teslathon has been here to my knowledge for 9 or 10. It’s usually on the same weekend every year, which for some reason happens to be Halloween. I don’t know whether that’s by planning or by accident! We’ve always been very welcome here and obviously with the connection to 18^th century technology we seem to fit in very well with the other machines and equipment at the pumping station. Of course, we all like to go and have a look round that sort of technology too.

October 2008

Fruit Fireballs

You may think that oranges seem are a fairly boring sort of fruit. Discover their more exciting side in this simple experiment.

What you need

Orange peel, ideally from a large orange with a thick juicy skin

A candle

What to Do

If you bend a piece of orange peel you often get a spray of orange oily stuff coming out. The idea is to direct this spray upwards into the side of a candle flame.

Be careful, this can be more effective than you expect. Make sure that your hands and anything else easily damaged by flame is below the candle flame!

---

What may Happen

You should be able to produce an impressive fireball as the spray hits the flame.