## Plus Blog

April 22, 2009
Thursday, April 23, 2009

On Friday the 13th, in April 2029, the asteroid Apophis will pass close enough to the Earth to be viewed with the naked eye. This will be an exciting event for stargazers, but for a short time in 2004 there was concern that this event would be cataclysmic. In December 2004 Apophis, named after the Egyptian serpent god who brings darkness to the Earth, was given a 1 in 37 chance of impacting with the Earth based on initial observations of the asteroid's orbit. Luckily, additional observations showed that the asteroid would just be a near miss in 2029, though there is still a slim chance of an impact during a pass in 2036.

While you breathe a sigh of relief, some people are already making plans for how to deal with any potential armageddons in the future. One such person is David French, a PhD student in aerospace engineering at North Carolina State University, who has has determined how to stop asteroids from impacting with the Earth by attaching a massive ball and chain...

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posted by Plus @ 10:26 AM

April 21, 2009
Wednesday, April 22, 2009

### A Gömböc for Cambridge

The University of Cambridge today received a Gömböc. It was donated by its inventors Gábor Domokos and Péter Várkonyi. But what is a Gömböc and what is the University going to do with it?

A Gömböc (pronounce goemboets) is a three-dimensional body with one stable and one unstable equilibrium point. If you put it down on a horizontal surface, it will start wobbling around until it has safely reached the equilibrium position, a bit like a Weeble toy. In theory, you could balance it on the unstable equilibrium point, but in practice that's really hard because the slightest nudge will make it fall over, just like a pencil that is balancing on its tip. Unlike a Wheeble, whose self-righting ability is down to a weight in its bottom, the Gömböc is homogenous inside: its density is the same everywhere, ie there is no off-centre weight which forces it to take on a particular position. The Gömböc is also convex.

The question of whether a convex and homogenous body with one unstable and one stable equilibrium exists in three dimensions was first raised by the Russian mathematician Vladimir Arnold. Mathematicians knew before that in two dimensions there are no such shapes, and they also knew that every three-dimensional object must have at least two equilibria. Domokos and Várkonyi started working on the question and did not only prove that the Gömböc exists, but also built one. In fact, they're building many, from different materials, and they're selling them on the Gömböc website.

The Gömböc is not only beautiful and interesting, but also sheds some light on how a certain species of turtle, with a Gömböc-like shell, manages to get back on its feet after it has been toppled over. Gömböcs need to be engineered to the highest levels of precision, otherwise they won't work. The Gömböc that was today donated to the University of Cambridge can be admired at the Whipple Museum of the History of Science. Plus will interview its inventors next month and you'll be able to read the interview here soon.

You can see a Gömböc doing its thing on YouTube, though the video clip is in German.

posted by Plus @ 1:15 PM

April 7, 2009
Wednesday, April 08, 2009

As part of our celebration of the International Year of Astronomy 2009 we brought you the article What happened before the Big Bang?, in which John D. Barrow tells us all about the bubbly multiverse we apparantly live in. Here is the podcast of this interview, so you can listen to these strange ideas with your own ears.

Listen to the podcast.

If this has whetted your appetite for astronomy, then why not take part in our online poll to nominate the next question we'll put to the experts.

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posted by Plus @ 8:51 AM

At 3:00 PM,  Erika said...

Hello, I do not know if it is possible to ask to John D. Barrow about the possibility of having in each bubble a different collection of laws of physics. Because if it is the case maybe they will have different elements and in that way will need different characteristics of expansion to be able to develop a sort of live, even a kind of civilization, on them.

Thank You.
Erika Roldan.
Guanajuato, México.

At 3:08 PM,  Erika said...

Hello, I will like to know if it is possible to ask to John D. Barrow if each of the bubbles can have its own laws of physics, without having to be the same as ours. Because if it is the case, it could be that the elements, or the equivalent of the elements in other bubbles, are different from the ones that we have. In which case the time to develop a sort of live of civilizations would depend of the characteristics of each bubble.

And I will like also to ask what kind of mathematical structure is used in modeling the multivers theory.

Thank You.
From:Erika Roldán.
Guanajuato, México.

At 9:02 AM,  The Plus Team said...

Dear Erika,

"Indeed, we know that in some theories of fundamental physics there is the possibility that important aspects of physics, like the strengths of basic forces or the masses of elementary particles, will fall out differently in the
different regions we have called 'bubbles'. Other local features, like the level of non-uniformity in the material density or the balance between matter and antimatter may also be different.

At present we don't believe there can exist atom-based life like ours except where things are very close to what we
observe in our 'bubble'.

String theory also allows the number of large dimensions of space to be different from one bubble to another. But we know that with more than three large space dimensions no atoms or planets or stars can exist. The attractive forces of nature fall off too rapidly with distance to hold things together. For example, in an N dimensional space the familiar 'inverse square' laws of gravity and electromagnetism become inverse (N-1) laws."

At 12:20 AM,  unRheal said...

Wouldn't we be seeing the light from at least *some* of these other bubbles - not sure how likely it'd be that most of them don't give off any sort of "light" that we can detect, but it sounded like "foam" means sort of lots and lots of bubbles - surely some would...(?)
Also aside note - the (voice, mostly) volume was too low, I had to turn it up so high that when something else made a sound it blasted out! (ended up saving it and amplifying & compressing it, then finished playing it)

At 7:54 AM,  Anonymous said...

Listening to the podcast some questions arose:

Isn't the foam explanation just another fairytale story similar to the concept of god or the existence of super big membranes (from string theory)? It does not seem to answer the question of the existence just outlines a possible way of thinking about it. Isn't it true that in essence he said that the "foam" exists eternally (according to the existing model) and that there is some eternal force/process in it that makes it to form bubbles of universes? The question remains where this energy and foam would come from? Some may say it randomly comes from NOTHING and then annihilates returning to NOTHING. Sometimes (randomly) the symmetry of the process is broken and then SOMETHING comes to existence for a while and that creates EVERYTHING else. The question then is what hellish IMPULSE would make the NOTHING to express itself as SOMETHING? Could that be a mindless GOD?

Kind Regard
George Spilkov
UK
P.S. I would appreciate if John D. Barrow would comment on that. Thank you.

April 2, 2009
Friday, April 03, 2009

### Maths in the movies and more

If you've been following Plus coverage on maths in the movies and theatre, and happen to find yourself in Edinburgh next week, then check out the Edinburgh International Science Festival's movie season and complementary talks. The themed season looks at the way mathematicians are represented in different kinds of narrative: pure fiction, fictionalised real life and documentary. The pure fiction offering is The Oxford Murders, starring John Hurt and Elijah Wood, screened on April the 7th. The Hollywood retelling of the story of maths students taking on the Las Vegas casinos is the second film, 21. It stars Kevin Spacey and is screened on the 9th of April. The season concludes on the 16th of April with the documentary N is a number, a film portrait of Paul Erdös. This screening will be followed by an audience and panel discussion.

To complement the film theme, on the 14th of April Academy Award winner David Baraff of Pixar Animation Studios will be giving a talk on the role of mathematical modelling in computer animation, illustrated with clips and computer graphics. There will also be a screening of Pixar's Oscar winning tale of a French rat's ambition to be a chef, Ratatouille. David Baraff will give a special introduction to the film at Filmhouse Cinema earlier that afternoon.

And if you prefer live entertainment to film, you could head for Allen Knutson's presentation on the relationship between mathematics and juggling. By mathematically analysing the process of juggling, Knutson, of Cornell University, found it was possible to discover new tricks that may never have come to light otherwise. This promises to be a most entertaining event as Allen demonstrates the principles involved using his dazzling juggling skills. The event takes place early in the evening of 14 April.

posted by Plus @ 9:49 AM

At 6:02 PM,  Peter Morgan said...

For the juggling, Allen Knutson has this nice PDF on juggling, http://math.ucsd.edu/~allenk/Roma2008/r.pdf, which starts out easy, gradually getting to be harder and harder math. It gives a little insight into how a mathematician approaches things.

March 31, 2009
Wednesday, April 01, 2009

### The Plus new writers award has now closed

The Plus new writers award 2009, our writing competition inviting you to share your favourite bit of maths with the rest of the world, has now closed. We've had a great response, so if you have submitted an article, but not yet received confirmation of receipt, don't worry. We're working through the stacks of entries and you'll hear from us within the next few days. Thanks for taking part!

posted by Plus @ 3:26 PM

March 29, 2009
Monday, March 30, 2009

In our online poll to find out what Plus readers would most like to know about the Universe, you told us that you'd like to find out what happened before the Big Bang. We took the question to the renowned cosmologist John D. Barrow, Professor of Mathematical Sciences at the University of Cambridge, and here is his answer. The Universe is an infinitely self-perpetuating foam of bubbles, it seems...

Read more and feel free to discuss the answer by leaving a comment on this blog. We'll periodically check back with the experts to try and answer interesting further questions.

This article is part of a series to celebrate the International Year of Astronomy 2009. The second poll to find out what you'd like to know most about the Universe is open now, so get voting!

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posted by Plus @ 11:00 AM

At 2:01 PM,  Common Tater said...

Barrow's remark in his final sidebar that dark matter "consists of stars that don't shine in the dark,..." seems a little beyond our current knowledge. While evidence indicates dark matter reacts to gravity, do we have data showing that its clustering actually produces star-like bodies? ...and thus, by extension, perhaps even "dark black" holes??

At 5:17 AM,  Anonymous said...

This may be the best bit of cosmology for the lay person I've ever read.

Until very recently there has been a strong bias toward the view that the observable universe is representative of the universe as a whole. Barrow does a very good job of looking beyond this to suggest that there is probably a whole range of "universes" and that ours seems special only insofar as we seem to be in the center of it.

Someday historians of science may look back on the conception of the "multiverse" in much the same way as we view the Copernican revolution and the vastly more unsettling recognition of "island universes" (galaxies). As first our solar system and then our galaxy seemed islands in something much more vast and unknowable, so too is the bubble we call the "universe"

At 9:18 AM,  The Plus Team said...

One of our readers asked (in response to the accompanying podcast) whether the laws of physics have to be the same in each bubble. We asked Professor Barrow and here is his response:

""Indeed, we know that in some theories of fundamental physics there is the possibility that important aspects of physics, like the strengths of basic forces or the masses of elementary particles, will fall out differently in the
different regions we have called 'bubbles'. Other local features, like the level of non-uniformity in the material density or the balance between matter and antimatter may also be different.

At present we don't believe there can exist atom-based life like ours except where things are very close to what we
observe in our 'bubble'.

String theory also allows the number of large dimensions of space to be different from one bubble to another. But we know that with more than three large space dimensions no atoms or planets or stars can exist. The attractive forces of nature fall off too rapidly with distance to hold things together. For example, in an N dimensional space the familiar 'inverse square' laws of gravity and electromagnetism become inverse (N-1) laws."

At 10:04 AM,  Scientist Exposer said...

What the author fails to do is answer the basic question, "What happened before the Big Bang?", or "What existed prior to the creation of the material universe?" He simply answers (paraphrasing), "The source was quantum foam", or "It has always existed", neither of which provide any sort of solid answer. Where did the 'quantum foam' come from?Until he can provide definitive information on the origin of life and the universe, then all his words are fantastic hot air at best and complete bluffing and deception at worst.

At 4:10 PM,  Medice said...

Is it possible that before the big bang the Universe or whatever we want to call it, was in fact composed of super condensed black matter. At the centre of this matter and due to extreme gravitational forces a portion,particle of light matter came into existance and the interaction of light matter and dark matter created the Universe as we know it today, ie dark matter is now at the edge of the universe and accelerating pulling the exisitng Galaxies with it ,expanding the universe. When the fabric of the dark matter becomes for want of a better word thinned out,the accelerating light matter will come into contact with sufficient dark matter to reverse the whole process making the universe 99.999% dark matter, unitl the gravitational forces once again create particles of light matter and once again interact with the dark matter, thus repeating the whole exercise again and again. Also could we know call the God particle the initial interacting light material