CDT rewrite toolbox

So, my colleagues have developed a CDT program that's usable. Fortunately for me, it's in LISP, which lacks parallel processing, modern libraries, a nice IDE, and the other goodies I've become accustomed to in my work life. (That means I get to figure these features out and thereby contribute!)

Enter Visual Studio 2008, IronPython, and IronScheme.

Setting up IronScheme with Visual Studio 2008 was usefully detailed here: (note, you need RegPkg via the Visual Studio 2008 SDK)

Setting up IronPython with Visual Studio 2008 via IronPython Studio (integrated setup):

And voila, no more excuses to complain about development.

(Yes, the end goal is to make it Python and cross-platform, although I'm really eying F#)

Hapkido Practicum Fall 2009

Physical Education Program, UC Davis

Hapkido Practicum

Fall Quarter, 2009

Instructor: Adam Getchell

Disclaimer: Techniques shown here are meant for informative/illustrative purposes. Just because I provide a link here, does necessarily mean I fully agree with all of the content shown. It does mean I think there is value in some of what is being demonstrated. As with all endeavors, a component of critical thinking is necessary.

If something shown here works and makes sense to you, great! Practice diligently.

If you don't understand or agree with something here, think about it, ask questions, form your own conclusions, and adjust your training accordingly. Martial Arts is an individual affair, albeit one with a common set of core principles derived from physics, anatomy, psychology, and other quantifiable discliplines.

In a time of crisis you do not necessarily have time to think!

Neither should you lose your wits about you. One of the best ways to avoid this is to know, in advance, what you are prepared to do, and commit to doing so. If (or when) the moment comes, you have a basis for action.

9.28.09

Discussion: Syllabus
Warmups: Running, circling, burpees, cartwheels, gymnastics forward roll
Techniques: Forward roll, footwork, elbow strikes


Further updates can be found at: http://docs.google.com/View?id=dckp3cwx_62csk8r4gk

Can LIGO detect a graviton?

A lecture given 10/27/08 by Professor Freeman Dyson of the Institute of Advanced Studies at Princeton, in honor of the 100th anniversary of the founding of the University of California, Davis.

E=\left(\frac{c^{2}}{32\pi G}\right)\omega^{2}f^{2}

is the energy per gravity wave, where f is the dimensionless amplitude/strain.

E_{s}=\frac{\hbar\omega^{4}}{c^{3}}

is the energy per graviton, taken from $\hbar\omega$ energy times $\frac{\omega^3}{c^3}$ density

f=\left(32\pi\right)^{\frac{1}{2}}\left(L_{p}\frac{\omega}{c}\right)

is the strain per graviton.

L_{p}=\left(\frac{G\hbar}{c^{3}}\right)^{\frac{1}{2}}=1.4\times10^{-33}cm

\delta=\left(32\pi\right)^{\frac{1}{2}}L_{p}

Gives the linear displacement per graviton.

Note that spherical objects can't radiate gravitational waves, and that binary stars produce kilohertz gravity waves.


LIGO's threshold is therefore $10^{37}$ gravitons.

M\delta^{2}\geq\hbar T

is the uncertainty in position and velocity.

D\leq\left(\frac{GM}{c^{2}}\right)

(from combining previous two equations)

\delta^{2}\geq\frac{\hbar D}{M_{s}}

\frac{GM}{c^{2}}\geq\left(\frac{c}{s}D\right)>D

exceeds the Schwarzschild radius, so impossible.


Then the Bohr-Rosenfeld argument is:

\Delta E_{x}(1)\Delta E_{x}(2)\approx\hbar\left|A(1,2)-A(2,1)\right|

where A(2,1) is the field from dipole 2 at location 1.


Then the detector is described by:

D_{ab}=m\int\Psi_{b}^{*}xy\Psi_{a}d\tau

where a is the initial state, b is the final state, and m is the detector mass.

\sigma(\omega)=\left(4\pi^{2}G\frac{\omega^{3}}{c^{3}}\right)\sum_{b}\left|D_{ab}\right|^{2}\delta(E_{b}-E_{a}-\hbar\omega)

S_{a}=\int\sigma(\omega)\frac{d\omega}{\omega}

is the logarithmic average taken over the graviton cross section.

S_{a}=4\pi^{2}L_{p}^{2}Q

Now consider the gravitophotoelectric effect, where the graviton removes an electron.

Q=\int\left|\left(x\frac{\partial}{\partial y}+y\frac{\partial}{\partial x}\right)\Psi_{a}\right|^{2}d\tau

Q=\frac{\int\bar{r}^{4}\left[f'(r)\right]^{2}d\bar{r}}{\int r^{2}\left[f(r)\right]^{2}dr}

\int r^{4}\left[f'+\left(\frac{3}{2}r\right)f\right]^{2}dr>0

Q>\frac{3}{4}

f(r)=r^{-n}e^{-\frac{r}{R}}

Q=1-\frac{n}{6}

4\pi^{2}L_{p}^{2}=4\pi^{2}G\frac{\hbar}{c^{3}}=8\times10^{-65}cm^{2}

This means that if you take a detector the mass of the Earth, squash it into a large flat sheet, and run it for the lifetime of the universe, you'll detect 4 gravitons.


From the Sun, there are $10^{8}$W of gravitons and $10^{25}$W of neutrinos, and we can detect gravitons about $10^{-35}$ less than neutrinos.

Special thanks to LaTeXMathML and yourequations.com! If you see funny symbols between dollar signs (for some of the equations), you need to pick a MathML capable browser. Most of the equations, however, are handled by yourequation's Javascript LaTex renderer.

N.B. There's a good followup post on Cosmic Variance, along with an earlier entry giving some good background information.

A Nobel Pursuit

Well, the Nobel Prizewinners are to be announced tomorrowTuesday. In the spirit of fun (and to demonstrate how much science really does advance), here are some predictions and other fun facts gleaned from around the 'Net:

Can you predict the Nobel Prizewinners in Chemistry & Physics by counting citations? Apparently not:

http://www.symmetrymagazine.org/breaking/2008/08/27/nobel-prize-citations/

Since this is an election year, it's interesting to note that 61 Nobel Laureates (including 22 physicists) -- the highest ever -- support Barack Obama for President:

http://sefora.org/2008/09/25/61-nobel-laureates-in-science-endorse-obama/

Perhaps it's because Obama/Biden actually have a cogent science policy, and happen to believe scientists when they talk about evolution or global warming.

Interestingly, Reuters seems to think citations count for potential Nobel prizewinners:

http://physics.about.com/b/2008/10/04/2008-nobel-prize-coming-soon.htm

They think the contenders are:

• Vera Rubin at Carnegie Institute in Washington for her work on Dark Matter
• Andre Geim and Kostya Novoslev for Graphene

Physics World offers the following candidates:

• Daniel Kleppner at MIT for inventing the hydrogen maser
• Berkeley’s Saul Perlmutter and Brian Schmidt at the Australian National University for their discovery that the universe’s rate of expansion is increasing…leading to the concept of dark energy
• MIT's Alan Guth and Andrei Linde at Stanford University for their work on inflation
• Chapman University's Yakir Aharanov for the Aharanov-Bohm effect and Michael Berry at the University of Bristol for the Berry phase -- the AB effect being related to the Berry phase
• John Pendry of Imperial College and Duke University's David Smith for their prediction and discovery of negative refraction
• Roger Penrose at Oxford University and Cambridge's Stephen Hawking for their contributions to general relativity theory and cosmology
• Atsuto Suzuki from Japan's SuperKamiokande experiment and Art MacDonald from SNO in Canada for their work on neutrino oscillations

Who am I going to pick? Well, not because of any insight, but because of fondness for the topic I'm going with one of the cosmological predictions, either inflation, dark matter, or dark energy. Maybe they'll all be grouped together.

Tune in tomorrowTuesday to see who wins!

Update: Nambu (of the Nambu-Goto action for bosonic string theory), Kobayashi and Masakawa (of the Cabbibo-Kobayashi-Masakawa matrix which describes flavor-changing weak decays) share the Nobel prize for Physics in 2008, quite deservedly, for discovery of spontaneous symmetry breaking.

Are we living in a simulation?

Today I came across one of Dr. Nick Bostrom's existential philosophy papers regarding life vs. sim-life (aka are we living in the Matrix?).

To me, the really interesting question is the assumption of substrate-independence (because I don't believe we're living in a simulation, more on that in a bit) -- that sentience, sapience, and self-awareness can arise from any appropriately complex material, including computer processors. Is there some minimal complexity bound for intelligence? (First, tell me what you mean by intelligence.) On one hand, we already know that a virus is just a particular aggregation of molecules, and that any assemblage of those particular atoms will exhibit the same viral behavior. On the other, does that extend to a connection between viruses and the rest of the living world, and by analogy, to bottom-up intelligence?

Will computers be able to exhibit sentience, sapience, or self-awareness?

As an aside, although most people seem to know Seth Lloyd's paper on the ultimate limits of computing, I tend to prefer Warren D. Smith's Fundamental Physical Limits on Computation and Fundamental physical limits on information storage as being more useful equation-wise (and he has very interesting papers on election systems and voting, which doesn't surprise me when it concludes that our current voting system is nearly the worst mathematically possible, and that Range Voting is a much better algorithm).

(Note that some the papers are in PS format, so you will need a PostScript reader such as GSview along with GPL Ghostscript to read.)

Before I get too sidetracked, let me outline my reasoning for why I don't believe we're living in a simulation:

• The total entropy/information of our Universe is bounded at < 10E123 (due to the Holographic principle)

• A simple quantum computer with 500 entangled pairs generates more information than could be simulated by any non-quantum computer in this Universe (2^500 >> 10E123)

• If the Universe is not simulated to a quantum degree of accuracy, the simulation can be immediately exposed via Bell's inequality

• Thus, in order to create a virtual universe sufficient to withstand experimental quantum physics tests, you need 10E123 qubits (e.g., the Universe)

Anyways, this is a very interesting topic, but I should continue my sidetracking avoidance and get back to my research.

Causal Dynamical Triangulations updates

The papers to read to get started:

A discrete history of the Lorentzian path integral

Reconstructing the Universe

Then the usual:

Dynamically Triangulating Lorentzian Quantum Gravity

Emergence of a 4D World from Causal Quantum Gravity

Semiclassical Universe from First Principles

Spectral dimension of the Universe

(Thanks to this post from Marcus)

And finally, the current literature on ArXiv.

Cosmology and Quantitative Biology

Went to an interesting seminar today about detecting traces of the reheat portion of the Hot Big Bang (the part that occurs after inflation), papers not yet out on arxiv (links posted here when they come out).

The interesting bits to relay back here are:

1. Any symmetry breaking (Higgs, for example) invariably generates gravity waves. Thus, it's possible for to use gravity waves to probe all the way back to inflation, 10E-35 seconds.

2. These gravity waves can be, in principle, detected by tabletop sized experiments! (There's a group trying to do that now). Unfortunately, there are issues of sensitivity that will make this rather difficult, but perhaps by, oh, 2020 we may detect relic gravity waves in the same way we've already detected the CMB.

3. Another cosmic relic is leftover magnetic fields, of which theory predicts their strength and scale should be equivalent to what we're seeing today as galactic and intragalactic magnetic fields.

4. Our guest seemed to expect to see copious production of strings and textures, which should be signified by their gravitational traces and provides further experimental tests of the stringscape.

And in some other news, here's a really fascinating article on bateriophages (viruses that infect bacteria) with some really nifty discussion points related to our nanotech thread. I won't spoil the article, it's well worth the read (it serves as a handy primer for nanotech issues), but an interesting result is the calculation of pressure inside the hard shell of a bateriophage, with experimental support, which shows that:

1. Bacteriophages have double-helix DNA to serve as a spring to provide packing energy

2. Bacteriophages rely upon this pressure to propagate, at least initially, into bateria.

3. Viruses are basically mechanical, inanimate objects. They don't do anything except replicate, and any inanimate matter assembled into the particular protein configuration of a virus will behave like that virus; on the flip side, viruses have the exact electrical properties of any other similar-sized particle in a colloidal suspension.

Ultra-strong electric and magnetic fields, monopoles

Response of Polyatomic Molecules to Ultrastrong Laser- and Ion-Induced Fields

Physics in Ultra-strong Magnetic Fields