## Posts

Meetup : Singapore September 2011 2011-08-19T14:49:57.053Z

Comment by sriku on Meetup : Singapore September 2011 · 2011-09-03T05:02:00.996Z · LW · GW

No response till the last day!

Comment by sriku on Meetup : Singapore September 2011 · 2011-08-20T19:01:38.448Z · LW · GW

Please do write a comment if you'd like to attend and whether you'd like to discuss a particular topic or just want the first one to be social, suitability of time and place, etc.

Comment by sriku on Question about meetup location address format .. · 2011-08-19T14:37:35.418Z · LW · GW

ok. That's a bit of a problem since University Town is so spanking new that it isn't on google maps yet! I'll approximate it.

Comment by sriku on Decoherence as Projection · 2011-07-20T11:32:52.903Z · LW · GW

"All right," you say, "that just seems weird." You pause. "So it's probably something quantum."

Indeed it is.

Don't oriented oscillating E,B fields explain this adequately at the macroscopic level? If you orient a polarizer at an angle theta to the orientation of the E field of the electromagnetic wave (i.e. light), the field gets projected as Ecos(theta) (the component perpendicular to the polarizer gets absorbed) and so the intensity goes as E^2cos^2(theta). That obeys the same mathematics without invoking the quantum magic wand.

Comment by sriku on The 5-Second Level · 2011-05-12T13:51:07.220Z · LW · GW

I haven't seen meditative practices described much here and I've known first hand how they can help with this level of introspection. So, for those who might wish to try, I'll briefly describe the plain instruction given to zen students. If you want to read in a bit more detail, the thin book "zen in plain English" is an excellent intro.

Sit in a quiet place, with lights dimmed, facing a wall, with your back straight (ex: use a cushion for lower back support). Half-close your eye lids. Adjust your breathing by taking a few deep breaths and then fall back to natural effortless breathing. Count your exhalations. Inhale-1-inhale-2-inhale-3...10 and cycle back to 1. If you lose count in the middle (yes you will) just start again at 1. Try this for at least 5mins. You can go up to 30 mins. That's all!

You can stop reading and try it.

When I began (don't laugh) I barely could count to 3. Here's how it went -

Inhale-1-inhale-2 ... what am I doing? What is this supposed to get me? Never stared at a wall before. Oh drats, back to 1.

Inhale-1-inhale-2... the plaster on the wall looks like a gorgon's face ... wonder what the others are thinking about .... Where was I? .. ok focus. 1..

Inhale-1-inhale-2... Damn is this what the famous sages did day in and day out? ... Oh shit lost it again. Am I that incapable of focusing? .. Ok back to 1

Inhale-1-inhale-2... Wait did I just chastise myself for something so trivial as counting my breath? .. (sigh) back to 1.

(Slowly the noise comes down and you get more real noise.)

Inhale-1-inhale-2 ... should I be taking deep breaths? Was the previous one long enough? ... Ok ok just sit and breathe ... Back to 1 ...

..... and so it goes. Just try it. The "back to 1" breakpoint works like a lens into your thought stream.

PS: apologies for the rough post. Just thought of writing this while on the bus.

Comment by sriku on Scholarship: How to Do It Efficiently · 2011-05-12T00:39:04.284Z · LW · GW

Thanks for validating what I do :)

What tipped off my original question was lukeprog's phrase "... now consumes whole fields of knowledge in mere weeks". I don't think I can manage that kind of speed with technical material! Months (without multiplexing) is more like it for me.

My question stands for anybody who has any tips for optimizing the "solve the exercises" method.

lukeprog: Your Anki tip is not in vain though. Still useful. Thanks.

Comment by sriku on Scholarship: How to Do It Efficiently · 2011-05-11T07:38:07.272Z · LW · GW

Universities subscribe to these databases. There is a kind of redirection via a proxy that happens when I'm logged in via my univ's network which allows me to download articles as you mention. I do have to agree to a "I declare I won't violate copyrights" button before proceeding.

Its cool to be in school :)

Comment by sriku on Scholarship: How to Do It Efficiently · 2011-05-11T07:34:07.188Z · LW · GW

Question to lukeprog: Do you have any efficiency recommendations for more technical subjects? Stuff on the lines of Eliezer's quantum physics sequence (aiming more than that, but at least that much). The thing that weighs on my mind most when dealing with such subjects is testing my own competence ... and so it takes me a considerable about of time.

Comment by sriku on The Best Textbooks on Every Subject · 2011-05-10T02:09:48.870Z · LW · GW

I must add that I kept both volumes with me under continuous reborrowal from the univ library for an entire year during my undergrad! Sad and glad that nobody else wanted it :)

Comment by sriku on The Best Textbooks on Every Subject · 2011-05-10T02:01:53.472Z · LW · GW

Subject: Basic mathematical physics

Recommendation: Bamberg and Sternberg's A Course in Mathematics for Students of Physics. (two volumes)

Reason: It is difficult to compare this book with other text books since it is extremely accessible, going all the way from 2D linear algebra to exterior calculus/differential geometry, covering electrodynamics, topology and thermodynamics. There is potential for insights into electrodynamics even compared to Feynman's lectures (which I've slurped) or Griffith's. For ex: treating circuit theory and Maxwell's equations as the same mathematical thing. The treatment of exterior calculus is more accessible than the only other treatment I've read which is in Misner Thorne Wheeler's Gravitation.

Comment by sriku on Newcomb's Problem and Regret of Rationality · 2011-05-10T00:05:25.782Z · LW · GW

It looks like you just restated the "paradox" - using one argument, it is "obvious" to pick B and using another argument, it is "obvious" to pick both.

Also, in general, do try to avoid saying something is "obvious". It usually throws a lot of complexity and potential faults into a black box and worsens your chances of uncovering those faults by intimidating people.

Comment by sriku on Newcomb's Problem and Regret of Rationality · 2011-05-07T06:30:19.761Z · LW · GW

How would Newcomb's problem look like in the physical world, taking quantum physics into account? Specifically, would Omega need to know quantum physics in order to predict my decision on "to one box or not to one box"?

To simplify the picture, imagine that Omega has a variable with it that can be either in the state A+B or B and which is expected to correlate with my decision and therefore serves to "predict" me. Omega runs some physical process to arrive at the contents of this variable. I'm assuming that "to predict" means "to simulate" - i.e. Omega can predict me by running a simulation of me (say using a universal quantum Turing machine) though that is not necessarily the only way to do so. Given that we're in a quantum world, would Omega actually need to simulate me in order to ensure a correlation between its variable and my choice, potentially in another galaxy, of whether to pick A+B or B?

Say |Oab> and |Ob> are the two eigenstates of Omega's variable (w.r.t. some operator it has) and the box system in front of me similarly has two eigenstates |Cab> and |Cb> ("C" for "choice") and my "action" is simply a choice of measuring the box system in the state |Cab> or in the state |Cb> and not a mixture of them.

If Omega sets up an EPR-like entanglement between its variable and the box system of the form m|Oab>|Cab> + n|Ob>|Cb>, and then chooses to measure a mixed state of its variable, say, |Oab>+|Ob>, it can bifurcate the universe. Then, if I measure |Cab> (i.e. choose A+B), I end up in the same universe as the one in which Omega measured its variable to be |Oab> and if I choose |Cb>, I end up in the same universe as the one in which Omega measured its variable to be |Ob>. Therefore, if our two systems are entangled this way, Omega wouldn't need to take any trouble to simulate me at all in order to ensure its reputation of being a perfect predictor!

That is only as far as Omega's reputation for being a perfect predictor is concerned. But hold on for a moment there. In this setup, the box system's state is not disconnected from that of Omega's predictor variable even if Omega has left the galaxy and yet Omega cannot causally influence it "contents". In my thinking, this is an argument against the stance of the "causal decision theorists" that whatever the contents of the box, it is "fixed" and therefore I maximize my utility by picking A+B. This is now an argument for the one boxers observing that Omega has shown a solid history of being right (i.e. Omega's internal variable has always correlated with the choices of all the people before), forming the simplest (?) explanation that Omega could be using quantum entanglement (edit: EPR-like entanglement) to effect the correlation, and therefore choosing to one box so that they end up in the universe with a million bucks instead of the one with a thousand.

So, my final question to people here is this - does knowledge of quantum physics resolve Newcomb's problem in favour of the one boxers? If not, the arguments certainly would be interesting to read :)

edit: To clarify the argument against the causal decision theorists, "B is either empty or has a million bucks" is not true. It could be in a superposition of the two that is entangled with Omega's variable. Therefore the standard causal argument for picking A+B doesn't hold any more.