Nima Arkani-Hamed on Naturalness

On November 14th, Nima Arkani-Hamed gave a talk titled Naturalness, the String Theory Landscape and the LHC.

By now I have forgotten most of the details of the talk, so below is a sketch of the small amount of notes that I took.

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The first part was to mention that the LHC will explore the weak energy scale. This energy scale is around 1 TeV. The weak scale is many orders above the Planck scale and many orders bellow the Hubble scale. This is part of the so-call Hierarchy problem.

This large leap make an "unnatural" fine tuning to 1 in 10^(-120) figures (in what I think is the cosmological constant, but I clearly suck at taking notes). Nima also mentioned that if you put a bunch of theoretical physicist in a spaceship, they will probably discover the Standard Model, with the right physics but all the numbers wrong.

An experimentalist fine-tunes a metal for example. (But I forgot the analogy here... :-( ).

Naturalness = compute until things blow in your face. For the weak scale to be natural, there should be some cutoff at 1 TeV. The LHC will run with 14 TeV in center of mass energy.

Nima then goes on to tell the story of the classical electron and the observation of the positron. Composite objects generate a doubling in degrees of freedom. For the weak scale there are two broad ideas:

1. Supersymmetry (SUSY) - Bosons related to fermions, couplings related. This phenomena should show up at the TeV scale.
2. Composites (Higgs made of techniquarks) - New dynamics.

Nima also mentioned that we should see some hints of string theory at the LHC. Both of this approached involve a LOT of new particles. But so far the number of experiments looking for deviations from the standard model have nothing.

An example of fine tuning is the nearly perfect alignment of the sun and the moon during an eclipse. The moon is the right size to cover the sun perfectly and leave a white halo.

The acceleration of the universe would be another finely-tuned aspect of the universe. If this were not the case, no structures would have ever formed. God? Other mechanism? Our planet is where structure is, around nebulae.

He then went on to talk about other universes, and looking for them. He also commented on split supersymmetry, but at this point I was already day dreaming. :-[

The end is approaching!

The world is not ending! On the contrary is getting better.

What is approaching is the end of the semester! Eeee! The first semester of graduate school. It was something to me, something very, very frustrating. But I have learned a lot. Sadly I have learned the hard way, by committing crucial mistakes in homeworks and bad judgments.  Some mistake include algebra and arithmetic mistakes ;-) . Other were volunteering to help type the string theory lecture notes with three core course, two lab sections, a seminar and a colloquium in my schedule. Oh well!

Tomorrow is my last "real" midterm. It is on Classical Mechanics: couple oscillations, 2-d motion including central forces and scattering, rigid bodies and rotations. Fun, fun! I have not studied that much, meaning that i have re-read the lecture notes and homework model solutions, but besides that not much. I think I could have prepare more, but I just want to get over with. A soft voice in the back of my head says Oh Mel! If you really want to get over with this, you should do better so you need not repeat the courses and waste more time! That might be true. But it is to late for that. I feel prepared (just like I felt the night before the Electrodynamics second midterm), and I hope I can at least understand the problems and work a great part of them in the test (unlike the Electrodynamics second midterm :-(). Then I will be relatively free, with some homeworks due on the week after Thanksgiving. I guess the "final" exam for Quantum Mechanics is on the last week of classes. I am really happy it is going to be a midterm-like test. :-)

The pope...

...of string theory.

I came upon these lecture series the other night. A set of them are three lectures by professor David Gross, from UCSB. Here is a transcript of the introduction of the introducer of David Gross:

To introduce David Gross tonight we are lucky to have in the audience another living legend of our time, professor Edward Witten of the Institute of Advanced Studies, the world's leader string theorist; often viewed as an intellectual leader in the tradition of Albert Einstein. Prof. Witten has received many top honors including the Dirac Medal, the Einstein Medal, the Fields Medal, several honorific doctorates and three years ago a National Medal of Science. Please welcome prof. Edward Witten.

Then Ed goes on to mention some facts about David and everything goes on. I have not being able to listen to the whole set of talks. But I got really annoyed by the introduction to Ed Witten.

I am not jealous of Ed. Well, maybe a bit. Of course! He might very well be one of the best string theorist. But the person says "leader string theorist". I think this is not fair. Maybe I do not know Witten's entire contribution to physics (and mathematics), but still. I believe that the main goal was to introduce professor Gross, who was the speaker of the night, the main attraction. Why would you want to start mentioning details about Ed Witten?

I guess Princeton is really happy they have Ed.

Mel in the City!

Last Friday I headed to New York City to meet with my girlfriend who was arriving at Pennsylvania Station. Well, technically at the Port Authority complex. It was the first time I headed by myself to the city. And it was scary as hell!

Well not that much. I come from Puerto Rico, where there is a total population that is maybe less than half of NYC's. I am come from the west part of the island, not from the relatively more crowded north, metropolitan area (San Juan). So when I got of from the train I was amazed to see the BIG number of people in the subway station. I know Penn Station is one of the busiest places in Manhattan (probably I am wrong...) but still. I had to walk slowly, looking around in an attempt to localized myself in the correct direction. People just bounced on me. Everyone with a steady, fast pace. All in a hurry.

I was not sure of where to take the subway uptown to Time Square. But I made it perfectly fine. Besides the $10.05 dinner consisting of 1 (one) slice of sausage pizza, 1 (one) slice of cheese pizza and 1 (one) medium coke. Oh well!

While waiting for the train at Stony Brook, I sat down in one of the (few) benches in the train station. I had the sun right in front of my face, so I decided to work on my homeworks. This bench is relatively big, but it has 3 rails dividing it into 4 bigger than average seats. I was seating in the far left corner with other people. An old man approach, so I decided to roll to the side, since I believed that we both could fit in the "single" seat. He turned away, but a "bigger" lady approach and said to me "Excuse me but I AM going to seat here." I really had to roll to the side. We were very tight and uncomfortable but I smiled as the woman sat down and let out loud an "Oh shit..." while sitting. I continue working out a solution to a boundary-value problem for Magnetism. She turned and asked me if she was covering me. I then realized I did not longer had the bright sun in my face (she was THAT big).

I smile at her and said "I am fine."

The energy crisis around the corner...

Some time ago, (on October 10th, 2006) I attended the physics and astronomy colloquium at Stony Brook. It was by prof. Albert Bartlett from Univ. of Colorado, Boulder. It pretty interesting, and sad.

The main idea of the talk was that we have been very ignorant about the fossil fuel usage and it lifetime. He began his talk by stating that most of the problems we faced come from not understanding a simple mathematical function: the natural exponential growth. I forgot most of the details about it, but he mentioned that the world already crossed the peak of fossil fuel production, and now it is going down. I guess his purpose is to make people realize the seriousness of the issue and consider taking on the problem of developing a new, efficient energy source. I felt pretty bad with my dreams of fame and fortune as a worthless string theorist...

No matter how much oil people could discover, it wont last long. We are increasing the consumption rate each year. So eventually, it will all disappear. My Classical Mechanics professor mentioned that certainly we all will (hopefully) live to experience the crisis. I was still ignorant about it until I realized a small detail that made me feel REALLY worried.

So what if the cars stop, the airplanes, the production lines for food. Transportation of materials will be nearly impossible, in the sense that it could still be done, with more time and money, by the old fashion ways of horses or coal. Communications will fall back 200 years. And then I realized that the Internet will shut down.

!!!

What am I going to do with out the Internet! ;-)

But seriously, the Internet has change things. Think about all the daily transactions that are done over the Internet. All the infrastructure will be useless. We will end up in a huge junkyard. I can see how countries could start wars to get each other resources. I can see how people could start fighting each other just to survive, first with the actual luxuries of water, food and warm; and then just to survive. Of course this commodities are not present in all parts of the world.

We came a long way from the caves. Now we do not know how to live in the forest without being eaten by wild animals, or just even die of dehydration. Well, at least I am not ready for that.

It all sounds very sad. I do not know what to do. I do not think I could help with any physics. At least I will never propose any idea to build another power-sucking accelerator. Hope someone helps. Else, we and our children will live the consequences.

The posts I would like to (post?)

At some point I would like to comment on:

1. Energy crisis,
2. NYC,
3. Ed Witten

Soon!

I'm still alive!

After all that has happen, I am still alive and kicking (and also solving physics problems for my homeworks...)

I guess my last post was ages ago. I am happy to tell that after a couple of hours, my computer worked fine again. I have not used that stupid blanket again. It is evil!

Anyways, I have been really busy with lots of stuff. My midterm cycle is restarting again this coming Monday with Electrodynamics and next Monday with Classical Mechanics. At least I am done with my seminar talk on Orbital Angular Momentum of Light.

Just like the electron has an intrinsic angular momentum (Spin) and the extrinsic (Orbital), the photon also has polarization and phase gradients. These angular momenta give rise to all sort of nifty effects. It was pretty fun.

I got a book on Lie Algebras by H. Georgi. So far I have read the first part, but it is very interesting. I think it should be very useful for the first part of Warren's Field Theory class. That is basically all I have been doing on my path to String Theory, since I had to stop typing the lecture notes. So much work!

I found this graffiti on one of the blackboards in the D floor of the physics building. It is amusing since it reads "clowns to the left of me, jokers to the right".



The Physics building is to the left of the hall. To the right is the Math tower.