Ghosts lurking around in advanced physics

Jack Dikian

February 2012

Lurking deep at the core of Gauge Quantum Field Theory are two Russian ghosts called Faddeev and Popov - somewhat reminiscent of the ghost monsters in the old video game; Munchkin. Luckily for us, these ghosts are also thought to be “good ghosts”. The bad ghosts, which apparently also exist in the strange and schizophrenic world of quantum mechanics are another thing altogether.

As the theory goes, these ghosts where send for so as to avoid the over-counting in the complex area of theoretical physics, to fix gauges and make path integrals right.

In high school, we were taught classical mechanics (remember fiction, momentum, force, gravitation, etc) and one of the things we learned was that the path of say a moving object (think of a ball thrown across the room) was that for which the action is a single unique trajectory, i.e., a stationary action [formulation].

In the world of the quantum mechanics, however, the stationary action formulation of classical mechanics extends to the path integral formulation, where a physical system follows simultaneously an infinity of possible trajectories with associated probability amplitudes for each path being determined by the action for the path. Now, path integral formulation should yield unambiguous, non-singular solutions; which they don’t. To modify the action such that these calculations yield applicable results, the good ghosts are used to break the gauge symmetries and make things right.

So every gauge field has an associated ghost, and where the gauge field acquires a mass, the associated ghost field acquires the same mass in some cases.

The Search for the God particle in Europe

Jack Dikian

December 2011

The Higgs Boson, nicknamed the God particle is the quantum of the theoretical Higgs field expected to have a non-zero vacuum expectation value thus, as the theory goes giving mass to every elementary particle that couples with the Higgs field, including the Higgs boson itself.

Experiments attempting to find the particle are currently being performed using the Large Hadron Collider at CERN. Now, CERN may have confirmed this theory. Scientists hunting for Higgs boson say they've found "intriguing hints" but not definitive proof that it exists, narrowing down the search and hope to reach a conclusion on whether the particle exists by next year. So if it does exist, it can help explain why there is mass in the universe.

It seems the data indicates the particle itself may have a mass of between roughly 114 and 130 billion electron volts. One billion electron volts is roughly the mass of a proton. The most likely mass of the Higgs boson is around 124 to 126 billion electron volts.

This Innocuous 1923 Photographic Plate made our Milky Way far less special

Jack Dikian

December 2011

One of the framed pictures I have hanging in my study is the 1923 photographic plate made with the Mt. Wilson Observatory's 100 inch telescope. Edwin Hubble was examining photographic plates of the Andromeda Nebula M31, looking for a novae.

On the night of October 5-6, 1923, Hubble located three novae, each marked with an "N” on this plate. Later he discovered that one was actually a Cepheid star - crossing out the "N" he wrote "Var!" (see upper right of the plate).

Harvard astronomer Henrietta Leavitt (who because of her gender was not allowed to actually use the telescope) provided one of the most important keys in astronomy discovering that Cepheids, regularly varying, pulsating stars, could be used as "standard candle" distance indicators, or in other words an objective gauge to measure distance.

So Hubble, by identifying such a star realized that Andromeda wasn’t a small cluster of stars and gas within our own galaxy, but a large galaxy in its own right at a substantial distance from the Milky Way. Right there and then, in that instant, mankind understood that the galaxy our star is in is just one galaxy in a universe filled with galaxies.

Project Tuva and Feynman Lectures

Jack Dikian

November 2011

I was first introduced to the work of the great Richard Feynman when I came by Surely You're Joking, Mr. Feynman! (Adventures of a Curious Character) when I was 15 or 16. I can’t remember if I borrowed the book from my high school library, bought it at a place called the White Elephant or found it amongst hundreds of old Reader's Digest copies left behind in the family house we moved into around that time.

One thing is for certain. The book was truly enthralling – especially to a boy who grew up building Crystal radio sets, spending summer nights looking at the night skies, reading Parabola and cherishing the wonder of all. So coming across Surely You're Joking, soothed by it’s comforting and lighthearted tone was truly a discovery of a lifetime.

Fast forward – we’ve all debated the features and benefits of Microsoft over Apple, some of us have even queued for hours outside an Apple store in the hope to buy their latest gadget; impress our friends, impress ourselves.

Regardless of our biases there is one thing that musts be said about Microsoft. Their Project Tuva which is an enhanced video player platform released to host the Messenger Lectures series titled The Character of Physical Law given by Richard Feynman in 1964 is a must for all who are interested in theoretical physics and in a strange way history. I say history because apart from a good introduction to topics that are still current in physics there is pleasure in seeing how a college campus looked in the fifties,

The project was a collaborative effort between Bill Gates and Microsoft Research that is designed to demonstrate the potential of enhanced video to teach people about the "core scientific concepts" of Feynman's lectures using interactive media.

According to his video introduction, Gates saw the lectures when he was younger. He enjoyed the physics concepts and Feynman's lecturing style, and later acquired the rights to make the video available to the public. He hopes that this will encourage others to make educational content available for free.

Feynman in his The Character of Physical Law lectures makes the most on-point remark dealing with the difficulty of understanding Quantum mechanics. James Bradford DeLong (commonly known as Brad Delong) in the course of something or rather suggests that the theory of relativity really isn’t all that hard. At least, if your standard of comparison is quantum mechanics.

He goes on – ‘While relativity has a reputation for being intimidatingly difficult, it’s a peculiar kind of difficulty. But anyone who studies the subject appreciates that it’s a series of epiphanies the theory are models of clarity. Quantum mechanics is not like that.”

And Feynman:

There was a time when the newspapers said that only twelve men understood the theory of relativity. I do not believe there ever was such a time. There might have been a time when only one man did, because he was the only guy who caught on, before he wrote his paper. But after people read the paper a lot of people understood the theory of relativity in some way or other, certainly more than twelve. On the other hand, I think I can safely say that nobody understands quantum mechanics.

You can get to project Tuva and the lectures at

http://research.microsoft.com/apps/tools/tuva/

The God Particle

Jack Dikian

October 2011

The Higgs boson is sometimes referred to as "the God particle" after the title of Leon Lederman's book, The God Particle: If the Universe Is the Answer, What Is the Question?

The Standard Model of particle physics is a theory concerning the electromagnetic, weak, and strong nuclear interactions, which mediate the dynamics of the known subatomic particles. The Standard Model gives us a framework for our understanding of the fundamental particles and forces of nature.

A theory to answer why particles have the masses they do or why they have any mass at all, however, isn’t so straightforward. Back in the early 60’s Peter Higgs proposed, the idea that space is permeated by a field, similar in some ways to the electromagnetic field. As particles move through space they travel through this field, and if they interact with it they acquire what appears to be mass. The Higgs boson is thought to give all matter mass.

This is similar to the action of viscous forces felt by particles moving through any thick liquid. The larger the interaction of the particles with the field, the more mass they appear to have. Thus the existence of this field is essential in Higg's hypothesis for the production of the mass of particles. As well as possibly explaining how particles receive their mass, some think it could also explain how the universe got its shape.

A theory put forward by researchers at Switzerland's École polytechnique fédérale de Lausanne argue that the Higgs boson might allow us to account for inflation, the otherwise unexplained process in which the early universe grew by a factor of at least 10^26 in an instant.

The Higgs boson is, however, the only elementary particle in the Standard Model that has not yet been observed in particle physics experiments.

Many universe theory explains a lot of things

Jack Dikian

September 2011

Inflation theory is the theorized extremely rapid expansion of the early universe by a factor of at least 10^78 in volume. The inflationary epoch lasted from 10^36 seconds after the Big Bang to approximately 10^33 seconds. This is a mind-boggling small period of time. It’s 0.000000000000000000000000000000000000 of a second after the big bang.

There are a number of variants to inflation theory or inflation models. An interesting model is the eternal inflation, which says (roughly speaking) that shortly after the Big Bang space-time expanded at different rates in different regions of the early universe, giving rise to bubble universes (that may function with their own separate laws of physics.

Our universe might just be one of many. While the concept is bizarre, it's a possibility, according to scientists who have devised the first test to investigate the idea at Imperial College London. The basic premise of the study is to look for collisions between universes by examining tell tale signs left behind in the cosmic microwave background radiation. This is the diffuse (thermal radiation) light left over from the Big Bang and pervades our universe.

Researchers used data from the Wilkinson Microwave Anisotropy Probe (WMAP) identifying four regions in the universe as promising candidates. However, statistical analyses suggested these patterns were likely to be random, resembling the circular shapes of collisions simply by coincidence. The European Space Agency's Planck satellite data set to be released in 2013, and the researchers plan to look again, surveying in particular the four areas of interest from this study.

A researcher from the University of British Columbia in Canada, agrees that the present data from WMAP is not likely to be precise enough to make a definitive statement, also excited by what the more detailed data from the Planck satellite might revel.

The obvious benefit that a multi-verse theory provides is an explanation for the strange coincidences in our own universe. Many of the fundamental constants such as the strength of gravity and the speed of light, seem perfectly calibrated to produce a universe in which galaxies, stars, planets and even life can form.

The scientists detailed their study in two research papers published recently in the journals Physical Review Letters and Physical Review D.

We are living but on a spec of dust looking out into the darkness

Jack Dikian

September 2011

The more I think about just how much we have been able to infer about the universe we live in the more amazing it all seems. I mean, here we are living on an unassuming rock orbiting a star near the outskirts of a galaxy. Our galaxy is estimated to contain 200 to 400 billion stars. Current estimates guess that there are 100 to 200 billion galaxies in the Universe. The universe is vast and we are living but on a spec of dust looking out into the darkness, looking back in time, and trying to make sense of it all.

The WMAP Explorer mission that launched June 2001 to make fundamental measurements of cosmology is analogies to a trapdoor spider coming out of its silk-lined burrow to examine the perimeter surrounding its burrow before it goes back inside to think about how might other terrains be like, what kind of soils, how small puddles of water be compared to vast oceans, and so on and so forth.

But, that’s exactly what the WMAP has been able to achieve. It has been able to study the properties of our universe as a whole. WMAP has been stunningly successful too, producing our new Standard Model of Cosmology. The 7-year data provide compelling evidence that the large-scale fluctuations are slightly more intense than the small-scale ones, a subtle prediction of many inflation models.

One of the problems the Big Bang theory was not able to explain is the horizon problem. Distant regions of space in opposite directions of the sky are so far apart that, assuming standard Big Bang expansion, they could never have been in causal contact with each other. This light travel time between them exceeds the age of the universe. Yet the uniformity of the cosmic microwave background temperature tells us that these regions must have been in contact with each other in the past.

The Inflation Theory, developed by Alan Guth, Andrei Linde, Paul Steinhardt, and Andy Albrecht, offer a solution to this and several other open questions in cosmology. Inflation supposes a burst of exponential expansion in the early universe, assuming distant regions of the universe were actually much closer together prior to Inflation than they would have been with only standard Big Bang expansion. Thus, such regions could have been in causal contact prior to Inflation and could have attained a uniform temperature.

Other reading

Alan H. Guth & Paul J.Steinhardt, "The Inflationary Universe", Scientific American, May 1984.

Andrei Linde, "The Self-Reproducing Inflationary Universe", Scientific American, November 1994.

Scott Watson, "An Exposition on Inflationary Cosmology", WWWarticle, 2000.

Alan H. Guth, "The Inflationary Universe : The Quest for a New Theory of Cosmic Origins", 1998.