Friday, October 30, 2009

How many Multiverses are there?

by Amanda Gefter - New Scientist

HOW many universes are there? Cosmologists Andrei Linde and Vitaly Vanchurin at Stanford University in California calculate that the number dwarfs the 10 Exp 500 universes postulated in string theory, and raise the provocative notion that the answer may depend on the human brain.

The idea that there is more than one universe, each with its own laws of physics, arises out of several different theories, including string theory and cosmic inflation. This concept of a "multiverse" could explain a puzzling mystery - why dark energy, the furtive force that is accelerating the expansion of space, appears improbably fine-tuned for life. With a large number of universes, there is bound to be one that has a dark energy value like ours.

Calculating the probability of observing this value - and other features of the cosmos - depends on how many universes of various kinds populate the multiverse. String theory describes 10 Exp 500 universes, but that just counts different vacuum states, which are like the blank canvases upon which universes are painted. The features of each canvas determine what the overall painting will look like - such as the laws of physics in that universe - but not the details.

Thanks to the randomness of quantum mechanics, two identical vacuum states can end up as very different universes. Small quantum fluctuations in the very early universe are stretched to astronomical scales by inflation, the period of faster-than-light expansion just after the big bang. These fluctuations lay down a gravitational blueprint that eventually determines the placement of stars and galaxies across the sky. Small differences in the form of these fluctuations can produce a universe in which the Milky Way is slightly bigger, or closer to its neighbours.

So just how many of these different universes can inflation's quantum fluctuations produce? According to Linde and Vanchurin, the total is about 10 Exp 10 Exp 10,000,000 - that's a 10 raised to a number ending with 10 million zeros ( Suddenly string theory's multiverse of 10 Exp 500 universes is looking rather claustrophobic.

might be, however, that this number is irrelevant, and that in a world ruled by quantum physics what matters is how many universes a single observer can distinguish. "Before quantum mechanics," says Linde, "we thought that 'reality' was a well-defined word." In classical physics, observers are irrelevant - we simply want to know how many universes exist.

For the Rest go to: New Scientist.

The Restricted View - Same Article

Quantum theory splits the world into two parts: the system under study and the rest of the world, which contains the observer. The system hovers in a ghostly state of near-existence made up of a host of possibilities until the observer makes a measurement - and so reduces this to a single reality.

Cosmology suffers from the paradox that no observer can be outside the universe - so the universe is doomed to spend eternity as nothing more than a vague possibility. The lesson of quantum cosmology is that we can't talk about the universe as a whole, but only what a given observer inside it might measure. Applying that lesson to the multiverse, Andrei Linde and Vitaly Vanchurin suggest that what matters is not the total number of possible universes, but the number of universes a single observer could distinguish.

If that observer is a human, the brain limits the amount of information they can register. But any observer - even an inanimate one such as a galaxy - is limited in the information it can store. These limitations in what observers can measure whittle down the number of universes that come into play in cosmological predictions. That means an observer might make a difference in explaining the value of things like dark energy.

Sunday, October 25, 2009

Seven Questions that Keep Physicists up at night

It's not your average confession show: a panel of leading physicists spilling the beans about what keeps them tossing and turning in the wee hours.

That was the scene a few days ago in front of a packed auditorium at the Perimeter Institute, in Waterloo, Canada, when a panel of physicists was asked to respond to a single question: "What keeps you awake at night?"

The discussion was part of "Quantum to Cosmos", a 10-day physics extravaganza, which ends on Sunday.

While most panelists professed to sleep very soundly, here are seven key conundrums that emerged during the session, which can be viewed here.

Why this universe?

In their pursuit of nature's fundamental laws, physicists have essentially been working under a long standing paradigm: demonstrating why the universe must be as we see it. But if other laws can be thought of, why can't the universes they describe exist in some other place? "Maybe we'll find there's no other alternative to the universe we know," says Sean Carroll of Caltech. "But I suspect that's not right." Carroll finds it easy to imagine that nature allows for different kinds of universes with different laws. "So in our universe, the question becomes why these laws and not some other laws?"

What is everything made of?

It's now clear that ordinary matter – atoms, stars and galaxies – accounts for a paltry 4 per cent of the universe's total energy budget. It's the other 96 per cent that keeps University of Michigan physicist Katherine Freese engaged. Freese is excited that one part of the problem, the nature of dark matter, may be nearing resolution. She points to new data from experiments like NASA's Fermi satellite that are consistent with the notion that dark matter particles in our own galaxy are annihilating with one another at a measurable rate, which in turn could reveal their properties. But the discovery of dark energy, which appears to be speeding up the expansion of the universe, has created a vast new set of puzzles for which there are no immediate answers in sight. This includes the nature of the dark energy itself and the question of why it has a value that is so extraordinarily small, allowing for the formation of galaxies, stars and the emergence of life.

How does complexity happen?

From the unpredictable behaviour of financial markets to the rise of life from inert matter, Leo Kadananoff, physicist and applied mathematician at the University of Chicago, finds the most engaging questions deal with the rise of complex systems. Kadanoff worries that particle physicists and cosmologists are missing an important trick if they only focus on the very small and the very large. "We still don't know how ordinary window glass works and keeps it shape," says Kadanoff. "The investigation of familiar things is just as important in the search for understanding." Life itself, he says, will only be truly understood by decoding how simple constituents with simple interactions can lead to complex phenomena.

Will string theory ever be proved correct?

Cambridge physicist David Tong is passionate about the mathematical beauty of string theory – the idea that the fundamental particles we observe are not point-like dots, but rather tiny strings. But he admits it once brought him to a philosophical crisis when he realised he might live his entire life not knowing whether it actually constitutes a description of all reality. Even experiments such as the Large Hadron Collider and the Planck satellite, while well positioned to reveal new physics, are unlikely to say anything definitive about strings. Tong finds solace in knowing that the methods of string theory can be brought to bear on less fundamental problems, such as the behaviour of quarks and exotic metals. "It is a useful theory," he says, "so I'm trying to concentrate on that."

For the rest go to New Scientist

How your brain creates the Fourth Dimension

From New Scientist...

THE MAN dangles on a cable hanging from an eight-storey-high tower. Suspended in a harness with his back to the ground, he sees only the face of the man above, who controls the winch that is lifting him to the top of the tower like a bundle of cargo. And then it happens. The cable suddenly unclips and he plummets towards the concrete below

Panic sets in, but he's been given an assignment and so, fighting his fear of death, he stares at the instrument strapped to his wrist, before falling into the sweet embrace of a safety net. A team of scientists will spend weeks studying the results.

The experiment was extreme, certainly, but the neuroscientist behind the study, David Eagleman at Baylor College of Medicine in Houston, Texas, is no Dr Strangelove. When we look back at scary situations, they often seem to have occurred in slow motion. Eagleman wanted to know whether the brain's clock actually accelerates - making external events appear abnormally slow in comparison with the brain's workings - or whether the slo-mo is just an artefact of our memory.

It's just one of many mysteries concerning how we experience time that we are only now beginning to crack. "Time," says Eagleman, "is much weirder than we think it is."

By understanding the mechanisms of our brain's clock, Eagleman and others hope to learn ways of temporarily resetting its tick. This might improve our mental speed and reaction times. What's more, since time is crucial to our perception of causality, a faulty internal clock might also explain the delusions suffered by people with schizophrenia.

For the rest go to: New Scientist

Liverpool 2 Manchester United 0

After Four defeats in all competitions this victory was most welcome. The Reds are 6th in the League and only 6 points behind leaders Chelsea.

Other great results:
Bolton 3 Everton 2
Man City 2 Fulham 2 (Sky Blues drop points)
West Ham 2 Arsenal 2 (Ditto for Gunners)

Sunday, October 18, 2009

A great way to learn physics

Build one of these............
Source: Wondercoaster

Another Stupid Nazi Comparison

Yes that are innately stupid but even more ridiculous when they are sprouted by that so-called cunning linguist Noam Chomsky

Gushing Over Obama

Much ink has been wasted praising the 'mighty one'...but I had to laugh at this about a man crush

An Excellent Physics Resource Site

I encourage all High School and AP Physics teachers to check out this amazing Resource Site.

Saturday, October 17, 2009

Teacher's Diary Week 6

Well ....I have finally finished the Optics Unit with the Grade 10's and we will be embarking on the Climate Change Strand next week. The latter is a new unit that incorporates, but does not include all of the topics discussed under the old climatology unit of the previous curriculum. While the expectations are straight forward I believe that the skill section of this unit will allow the students to better interpret data and apply reason and critical thought to the analysis of such information. I will attempt to encourage as much debate as possible as the nebulous nature of the specifics of the topic begs for such an approach.

In the Grade 11 Physics course the kids are all gung-ho about their Wondercoasters (a roller coaster contest run by Canada's Wonderland). On the more formal side we are working through Newton's Laws, clearing up the obvious misconceptions as we go along. The students seem to be coming to terms with the importance of Free Body Diagrams and attacked the lab work with much enthusiasm. So far so good....but lets see what the quizzes deliver.

Sunday, October 11, 2009

No Sarcasm Intended.....

Chavez's thuggery continues

Pro-Chavez lawmakers deny the government plans to use the militias to break up street protests, saying the armed groups would be deployed only if Chavez declared martial law amid widespread political upheaval or natural disasters.

The predominantly pro-Chavez National Assembly approved the legislation Tuesday, giving a legal framework for a project begun by Chavez more than three years ago, when volunteers began receiving military training to prepare for what the leftist leader warned could be a U.S. invasion.

His critics expressed skepticism.

"The militias are for intimidating and terrorizing" those who take to the streets to protest against Chavez, said Stalin Gonzalez, an opposition politician who helped organize anti-Chavez demonstrations in recent years as a university student.

Source: Taiwan News

Quote of the Week

Republican Rep. Gresham Barrett on Obama winning the Nobel Peace Prize

"I'm not sure what the international community loved best," said Republican Rep. Gresham Barrett, a candidate for governor in South Carolina, "his waffling on Afghanistan, pulling defense missiles out of Eastern Europe, turning his back on freedom fighters in Honduras, coddling Castro, siding with the Palestinians against Israel, or almost getting tough on Iran."

Source: Chicago Tribune

Teacher's Diary - Weeks 3,4 and 5

To say that I am buried in work is an understatement. However its part of my role as a teacher and I wouldn't have it any other way. The new school is looking promising and the kids are great. We have all sorts of clubs and there are many students who are clearly not afraid to go above and beyond the curriculum. As someone dedicated to education this resonates very well with me.

I am closing on completing the Optics section with my Grade 10s. They write their unit ending test this coming week and have a kaleidoscope design project to hand in a few days later. It is important to keep challenging the 10s and encouraging an appreciation of the sciences as their follow through influences the future of our department and ultimately the school. Thankfully we have the support of the parents and the administration on this matter and have no shortage of students wishing to sign up for the myriad of science competitions that are now common place at the senior high school level.

On the physics front (with my Grade 11s) I have just started the Mechanics section having completed the Kinematics Unit. I spent some time on Projectile motion (PM)attacking the subject with computer simulations, discovery/thinking lab work and problems. PM can be a difficult topic for the students to master as they are still trying to come to terms with the idea of resolving a vector into components using the tools of trigonometry. The scaffolding necessary is a bit more intense than other topics and requires constant feedback and multiple assessments.

In short all is well (at least is seems so...I may yet get mugged around the corner). There are still some issues with respect to helping some of the struggling students with the material that I will work on in the next week or so. I also have a student teacher who will be assigned to me come months end. Since I am a great fan of mentoring I am looking forward to helping another teacher develop their pedagogic potential.

Saturday, October 03, 2009

Fifteen Annoyances on the Left

1. Maureen Dowd
2. Thomas Friedman
3. Alexander Cockburn
4. Noam Chomsky
5. Naomi Klein
6. Glenn Greenwald
7. Gore Vidal
8. Michael Lerner
9. Medea Benjamin
10. Avi Lewis
11. Rick Salutin
12. Ted Rall
13. Norman Finkelstein
14. Howard Zinn
15. John Pilger

Fifteen Annoyances on the Right

1. Pat Buchanan
2. Robert Novak (deceased)
3. Joseph Sobran
4. John Sununu
5. Justin Raimondo
6. Paul Craig Roberts
7. Taki
8. Ron Paul
9. Lew Rockwell
10. Paul Gottfried
11. Ann Coulter
12. Bay Buchanan
13. Karl Rove
14. Alex Jones
15. Scott McConnell

My Top Ten Political Pundits

1. Victor Davis Hanson
2. George Jonas
3. Charles Johnson
4. Sultan Knish
5. Jonah Goldberg
6. Steven Plaut
7. Thomas Sowell
8. John Ray
9. Tammy Bruce
10. Dennis Prager