physonaught

An economist and his friend were walking down the street, when they spied a 100$ bill lying on the pavement. The economist strode past without a second look. His friend tugged on his sleeve, "Why didn't you pick it up! That was 100$ !"

The economist snorts, and says, "If that was a real 100$ bill, someone else would have picked it up already."

A good mental model for graduate school is that it is a feudal system. There is essentially no oversight of professors by a larger executive branch. I mean, they can't literally murder you, but they can drive you to suicide. (Jason Altom)

If you get lucky, you get a professor that believes in you (this can be one of the most rewarding experiences I know of).

If you aren't lucky, then things will get really rough. I've seen professors: - Spike their student's candidicy at the last minute (meaning the student had to switch groups in their last year, essentially having to redo their PhD in another group) - Spike student papers - finding out where their former student was applying for jobs, calling and spiking their job application (talking shit) - various abuses (yelling at student for not working on Christmas, humiliating student for years in public, sexual harassment)

I could go on. If you haven't been through grad school, you might ask "why not leave/vote with your feet?"

But understand the power dynamic: in really broad strokes, the student works towards a reward (being a Dr/PhD) that will take, on average, 5-6 years. Getting that reward is completely up to your supervisor's discretion. It's like if you worked at a startup for six years for minimum wage, but if your boss agrees to it, you will get a million dollar payout (also, your boss can't be fired, ever.) And that's just a minimum-- success in academia is dependent on getting full throated letters of rec from your supervisor, so they also have to really like you.

So your professional success is completely up to one person: if they decide to fuck you over, that can be 4 years of work down the drain.

When I was in graduate school, I never saw the faculty/department intervene in any of the abusive situations. The only thing that protects students are soft processes, like knowing which professors are really bad. The Yelp idea is good, simply because it increases that ability.

And those abuses I talked about? A majority of my cohort dealt with that (at a large, well known University), it's not isolated to a few bad apples.

The physicists definition of time is "What clocks measure". It sounds like he was just saying the party line.

I though the article was cute, but I wouldn't go so far as to say it was crappy. The essence of the article was on point. You can't just report the time anymore, once special and general relativity become important, you have to report space-time. Sure, other effects are going to become important as well, but the essence of the article: time is not absolute, and this has practical difficulties for clock-makers, was well communicated.

That is true, but, (if you haven't already), I would recommend looking into the delayed choice quantum eraser experiment. I think it is probably more true to the essences of what the article was trying to communicate.

I don't think I can do the idea justice, but the basic idea is such: if you 'tag' the photons in the double-slit experiment by which path they went through, then you necessarily break superposition and won't see an interference pattern.

However, if you 'throw' away this information completely, the interference pattern re-emerges. The delayed-choice part of it is just a way to through away the 'tag' information after the photon has moved through the slits. It seems to suggest that you can uncollapse a wavefunction if you just erase any knowledge you have of the measurement you made. (I've probably butchered it, read here for more[1])

Although, honestly, you don't need retrocausality, and personally I think it has much more interesting applications to information theory (how does one destroy information? How does the wavefunction know about our records? What even is information, man? etc)

[1] http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser

I would be interested in looking at applications with applied electric/optical fields.

Could you shape the plasma after it was created, shaping the waveguide?

Some very cool physics involved-- a lot of basic quantum mechanics (electrons hopping on a lattice), but it has a lot of really broad implications about symmetries. There is a lot of recent interest in the butterfly [1,2].

It turns out that it is a very important state to study the Quantum Hall effect[3], and the fractional Quantum Hall effect[4], which seem to be in vogue in Condensed Matter physics these days.

Sorry to bog you down with details, I just wanted to mention how neat it is that Hofstadter's butterfly is still being studied today!

[1] http://www.nature.com/nature/journal/v497/n7451/full/nature1... [2] http://physics.aps.org/articles/v6/118

Here is a high level summary of the work, written by technology review[1].

Looks pretty neat!

[1] http://www.technologyreview.com/blog/arxiv/27394/