## Plus Blog

April 23, 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...

Labels:

posted by Plus @ 10:26 AM

April 22, 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 8, 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.

Labels: ,

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 3, 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.

April 1, 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 30, 2009
Monday, March 30, 2009

### What would you like to know about your Universe — The second poll

This poll is now closed. The most popular question was: "Are the constants of nature really constant?" We will publish the answer in an article and podcast on Plus shortly. Thank you for taking part!

This is our second online poll in our series to celebrate the International Year of Astronomy 2009. Choose your favourite question from the list on the right, and we'll put the one that proves most popular to world-leading astronomers and cosmologists, including Astronomer Royal Martin Rees and author and cosmologist John D. Barrow. The poll will remain open for a month and the answer will be published in a Plus article and podcast soon after. If your most burning question is not on this list, then leave a comment on this blog and we'll endeavour to include it in a future poll — there will be five more polls dotted throughout the year.

The most popular question in our first poll was "What happened before the Big Bang?". You can now read the mind-boggling answer here on Plus, and discuss it on our blog.

Labels:

posted by Plus @ 12:10 PM

At 11:20 AM,  Anonymous said...

I would be interested to know about the rings of Saturn. Particular points might be:
- Why is Saturn the only planet in the solar system with rings (or is it?)?
- How dense are the rings - would it be possible for a space vehicle to go through them or would it be destroyed in the attempt?
- How quickly are the rings orbiting the planet or are they in stationary orbit?
- What are the rings comprised of - dust, larger particles?
Terry Schooling

At 10:25 PM,  Anonymous said...

I would be interested to know if you could explain how gravity actually works: what is it about bodies with mass that attracts?
Richard Catterall

At 11:25 PM,  westius said...

I'd love John to explain what a "Boltzmann Brain" is - that was one of the freakiest things I heard at the very Early Universe conference in 2007 - a very odd merger of Physics, astronomy and philosophy!

At 12:21 AM,  Kc said...

Saturn is not the only planet with rings. All the gas giants have them.
- The rings are mostly dust,ice, and cosmic debris so any attempt to go through them would possibly destroy any ship that goes through it.

At 5:33 PM,  jesvin said...

In the last ever paragraph of 'A brief History of Time' Stephen Hawking predicts the unified theory, which can empower scientists, philosophers and public to know the nature of God. I would like to know the efforts in this direction, how do we get there and what are the immediate obstacles before us.

Also nice would be a discussion whether free will exists and whether the universe is deterministic; and are both concepts equivalent?

On matters closer to Earth, I wonder how the LHC finds answers within the terabytes streaming from its detecctors.

At 9:31 AM,  Plus said...

We would like to apologise to everyone who, due to a technical glitch on Plus, haven't been able to register their vote on this second poll. We're very pleased to announce the problem is now resolved, and you can once again tell us what you would like to know about your Universe!

Resuming normal transmission....

At 12:12 AM,  Dominick said...

What is the universe made of... quite a broad question. I was torn between this question, and the shape of the universe question. I eventually chose shape as my curiosity. I don't think "Why are planets round" warranted the opportunity to be on such a pole... it's clearly because gravity is a central force, so stuff settles that way. To the person who is curious how gravity works, read a bit about general relativity, Einstein answered that question with some math he borrowed from brilliant men. And Jesvin, as far as Stephen Hawking and his discussion of guts goes, there hasn't been much progress. Firstly, I hope it's understood that Hawking uses the word god as a metaphor, not unlike Einstien did. Secondly, look for a blog by Peter Woit of Columbia University called "Not Even Wrong." We, as physicists an mathematicians, are far from a unified theory of everything. In fact, it might not even be possible to come up with one.