Plus Blog

December 22, 2009
Tuesday, December 22, 2009

Researchers working on the Cryogenic Dark Matter Search experiment (CDMS) received an early Christmas gift last week when their detectors spotted evidence for the existence of dark matter, the mysterious substance that is believed to make up 25% of our Universe. The detectors, sitting half a mile underground in a disused mine in northern Minnesota, detected two events that may be results of dark matter particles bouncing off other atomic nuclei. It's the first time that such events were recorded by CDMS, and while they don't provide conclusive proof that dark matter exists, the detections have caused a stir in the scientific community.

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posted by Plus @ 11:54 AM

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December 18, 2009
Friday, December 18, 2009

In our last 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 how long a day is. We took the question to the physicist Nicholas Mee and here is his answer — and it's not 24 hours!

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posted by Plus @ 3:14 PM

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At 9:51 PM, Blogger Quantum_Flux said...

Nice, but shouldn't that analemma be shifted left by a few minutes to the intersection coincides with zero minutes?

 
December 18, 2009
Friday, December 18, 2009

If you are looking for something to while away the holiday, then this issue has plenty of ideas for you! We explore the power of origami to solve ancient (and very modern) problems, find the maths in fashion, and marvel at the complexities of church bell ringing. But it's not all fun and games, as we investigate the controversies surrounding breast screening and the maths behind drug-induced hallucinations, find out how to predict the impact of natural catastrophes, and answer some deep questions about the Universe.

Read issue 53 of Plus!

posted by Plus @ 3:55 PM

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December 11, 2009
Friday, December 11, 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 if time travel is allowed. We took the question to Kip Thorne, Feynmann Professor of Theoretical Physics, Emeritus, at the California Institute of Technology, and here is his answer.

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posted by Plus @ 11:05 AM

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At 2:00 PM, Blogger Ray said...

I know a little GR; but no Quantum Gravity and very little QM.
I interpret the article as saying that the consensus is: Quantum Gravity can not be fit into Godel's time-closed solution to GR. Is that correct? In that case the global topology would constrain the deeper theories. Put another way Quantum Mechanics can not be embedded/formulated on an arbitrary manifold.
These are questions; not statements.
Ray

 
At 9:25 PM, Blogger Quantum_Flux said...

It is the same thing for observer 1 to rapidly travel into the past as it is for observer 2 to rapidly travel into the future.

 
At 3:38 PM, Blogger Ray said...

I read references 2,3
3 is quite readable.
2 is tougher and I am not through.
The idea that some local properties can't be extended globally in some topologies is not as strange as it might seem at first glance; there are other examples.
I do have doubts about some of the reasoning; but that doesn't fault the reasoning just the presumptions.
I think its possible that the "energy conditions" are not the right analysis tool. Something along the lines of Entropy (Maxwell's daemon ) might be sharper in the mathematical sense.
Ray

 
At 5:32 PM, Blogger The Grin Reaper said...

Th relation to Casimir vacuums was fascinating. So is the solidarity of Hawking's argument.
Although the possibilities of time travel would lead to the age old grandfather paradox, and I am not sure as to what would be a right explanation. Maybe the Copenhagen interpretation of splitting states to maintain Quantum decoherence.
Cannot say anything conclusively.

 
December 11, 2009
Friday, December 11, 2009

Professor risk

Are you a committed non-smoker who loves rock climbing? Then, like most of us, your have an ambivalent attitude to risk. Some risks are so much fun they're worth taking, and others you definitely stay clear of. But what's the attitude of a risk professional like David Spiegelhalter, Cambridge Professor of Public Understanding of Risk (and regular contributor to Plus)? Find out in this short video posted on the Cambridge Ideas website.

posted by Plus @ 3:41 PM

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December 3, 2009
Thursday, December 03, 2009

Vaccination is an emotive business. The furore around the MMR vaccine and autism has shown that vaccination health scares can cause considerable damage: stop vaccinating, and epidemics are sure to follow. But how do scientists decide whether a vaccine and a vaccination strategy are effective and safe? We talk to Paddy Farrington, Professor of Statistics at the Open University. You can also read the accompanying article.

Listen to the podcast.

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posted by Plus @ 12:43 PM

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