What would you like to know about your Universe — The third online poll
This poll is now closed. The most popular question was: "What are dark energy and dark matter?" We will publish the answer in an article and podcast on Plus shortly. Thank you for taking part!
This is our third 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 four more polls dotted throughout the year.
Dark matter is possibly "easy" to determine: neutrinos have mass. That simple (but hugely ignored) fact could provide both sufficient mass and energy to explain the otherwise unobserved masses and energies that puzzle us.
But how Gravity works - well, that's something I would really like to know.
In our second online poll to find out what Plus readers would most like to know about the Universe, you told us that you'd like to know if the constants of nature really are constant. We took the question to cosmologist John D. Barrow, Professor of Mathematical Sciences at the University of Cambridge, and here is his answer. Please 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.
We took your question about the speed of light to John D Barrow and here is his answer:
"No, there can never be a proof that the speed of light is constant. Relativity theory requires the speed of light in vacuum to be constant and the same for all observers. All we can do is test whether that is true and hence whether the theory of relativity is a corrrect description of nature. There may be tiny quantum mechanical corrections to the theory which produce very small changes in
extreme environments (very small distance, high frequencies or strong gavitational fields)."
"An added subtlety is that in most of these possible worlds life cannot exist."
This leads to another question: what do you mean by 'life'? What makes life special? How can it be that there might be a world where rocks etc. can exist but 'life' (whatever definition you choose for that word) can't?
A constant is nothing but it is a derived numerical ratio between the two same fundamental quantities.The constant is said to be a point function,since it is constant at a point when it is made to travel at different atmosphere with different velocities,the value of constant may varie and moreover an example to say that the velocity of light is constant,when abody is made to move with a
velocity equal to light then the constant may vary relative to this object speed.so constant is an induvidual point function and independent from the different variables.
Next time you're off to the bookies to place your footie bets, you might be better off consulting a statistician than a football expert. On his Understanding Uncertainty website self-confessed football un-enthusiast David Spiegelhalter used a simple statistical model to predict the results of the last ten Premier League matches, which were played on the 24th of May 2009. In terms of predicting whether a game ended in a win, draw, or defeat for the home team, Spiegelhalter's model was right nine out of ten times, compared to the seven out of ten score achieved by the official BBC football expert Marc Lawrenson, and the model predicted two scores exactly.
Spiegelhalter and his co-authors Mike Pearson and Ian Short quantified the individual teams' attack strength and defense weakness based on their past performance, and then, with a little help from probability theory, used these ratings to work out the most likely outcome of a particular match. (You can see the details of this model on his website.) "These types of models have been refined over the years and are now used by bookies and sports betting companies, who employ experienced statisticians and make use of the latest computational methods," says Spiegelhalter. But he concedes that his very basic model might have been a bit lucky this time: "One thing you can bet on is that
simple models like this one will be very unlikely to out-perform the odds being offered by bookies, so don't use them to spot good bets!"
Spiegelhalter announced his prediction on the BBC Radio 4 programme More or Less, which was aired before the final match day, so you can be sure that no hindsight fraud was involved.
David Spiegelhalter is Winton Professor for the Public Understanding of Risk at the University of Cambridge and regularly writes for Plus (see for example his article on the 2006-2007 Premier League season). His Understanding Uncertainty website is designed to inform the
public about everything to do with risk and uncertainty, from health scares to predicting election results.
davids approach seems quite nice to me, so i think it takes into account all the strength and weakensses of both the teams, now leaving the thrill factor (which is still very much alive,as it is a guide only) i think if one is thinking of investing in sports picks ,the theory appears nice in principle,
At the very heart of sport is a fierce battle in which the combatants strive to outwit and outplay each other. Each thrust is matched by a parry and in the end, there can only be one winner. The rules of each sport dictate how that winner is determined, and whether it is football, tennis, golf or chess, it is those who perform best on the day who take home the glory. This latest installment of
the Plus sports page looks at two ranking systems that couldn't be any different from each other — those of sumo and chess.