drjesusphd

10 ms·

61.
by drjesusphd 8y ago
Yes, vibrations in a lattice are quantized: they can only occur at a discrete set of frequencies and energies.
62.
by drjesusphd 8y ago
"Sustainable Energy Without the Hot Air" by David MacKay - available for download ( http://www.inference.org.uk/sustainable/book/tex/sewtha.pdf ). It really illustrates the enormity of the energy prob
63.
by drjesusphd 8y ago
It says that capitalism fails without anti-trust enforcement. This has been known for a long time.
64.
by drjesusphd 8y ago
You might really enjoy this essay. It changed my life. http://webcache.googleusercontent.com/search?q=cache:Ph7Enkr... I came to terms with ideas like this by changing careers to a profession which, at least abstractly, ben
65.
by drjesusphd 8y ago
I think yours is the comment disconnected from reality. But I will say that westerners tend to over-estimate what is required to live "comfortably", but $100k in savings won't get you very far, even below the poverty level. $
66.
by drjesusphd 8y ago
"Quantum field theory in a nutshell" also covers this well.
67.
by drjesusphd 8y ago
I think both dark matter and dark energy are perfectly consistent with GR. Hitherto unobserved matter would contribute to the stress energy tensor and dark energy is (I believe - has this changed?) the cosmological constant.
68.
by drjesusphd 8y ago
This is the Bohr model of the atom, but was replaced by a proper quantum theory.
69.
by drjesusphd 8y ago
I would argue it's only "impossible" for the EU. The US could implement sound fiscal policy, but chooses not to. Whereas the eurozone states suffer a tragedy of the commons unless the fiscal structure of the EU changes.
70.
by drjesusphd 8y ago
There are many factors of the global economy that determine the market-determined yield at a given time. The only way a country being "good with money" is in comparison to the yield of other central banks at the same time. I don&#
71.
by drjesusphd 8y ago
Fusion is only necessary for long-term sustainability if you're talking about interstellar travel (and even then, fission may be fine). There's a real physical ceiling to how much power can be consumed on Earth's surface, reg
72.
by drjesusphd 8y ago
Depending on your definition of "reactor", it was either done decades ago, about to be done (or at least the scientific community is very confident they know how to do so), or several decades away.
73.
by drjesusphd 8y ago
Even coal power plants cost several billion. I don't think an order of magnitude reduction in cost is foolish to count on. The issue is the design of extremely specialized components, not necessarily the raw materials (except when they
74.
by drjesusphd 8y ago
Yes, neutron activation is an issue that needs to be handled safely. But the isotopes produced this way tend to be short-lived, with half lives around a decade. Not the same challenge of storing radioactive waste on geological timescales.
75.
by drjesusphd 8y ago
Right!? Such is the magic of orthogonal polynomials. If one chooses the integration grid to lie at zeros of the appropriate orthogonal polynomial, information is gained. https://en.wikipedia.org/wiki/Gaussian_quadrature
76.
by drjesusphd 8y ago
Gaussian integration. You might have heard of "2nd order" or "4th order methods to calculate an integral. This means that the error drops off with the number of sampling points like N^-2 or N^-4, respectively. But Gaussian qu
77.
by drjesusphd 8y ago
That's always the question, isn't it? Even if you could choose your job to fit the chosen task, what is worth your time and evergy at the expense of anything else?
78.
by drjesusphd 8y ago
> Worried about how we'll produce all that power? When getting stuff into orbit is sufficiently cheap it'll become economic to put solar collectors in orbit and beam energy back to Earth. I used to be a big believer in this. Bu
79.
by drjesusphd 8y ago
> Use the 15 minute rule to get started, only agree to do 15-20 minutes of work to see if you are flowing in that project, most of the time once you get started and loaded up the project in your mental space you can easily flow on it. I
80.
by drjesusphd 8y ago
Gothenburg, Sweden. Has a growing tech scene, English is spoken everywhere, a couple of good universities, surpringly affordable cost of living, winters are fairly mild (but long). Definitely has a healthy intellectual atmosphere, with lots
81.
by drjesusphd 8y ago
Horrifying in what way? In the sense of being nearly impossible to navigate taking into account their gravitational effects? If these black holes are just as dense as in the galaxy, wouldn't that make navigating the galaxy just as diff
82.
by drjesusphd 8y ago
I remember Carroll's Modern Astrophysics being very good. It's quantitative, so it helps to have some physics background.
83.
by drjesusphd 8y ago
In the play "No Exit", Sartre (through one of the characters) says "You are your life. And nothing else." It stands to reason that the "real you" never gets fully realized until you die.
84.
by drjesusphd 8y ago
I would imagine having the tools to shape your own behavior would pay divedends well beyond "learning some math".
85.
by drjesusphd 8y ago
> I’ve gotten to the point where I actually view people who listen to others and are open to changing their opinions when confronted with good advice as being much more intelligent than those who are sure they are right about everything
86.
by drjesusphd 8y ago
I've never thought of the equivalence principle like this. I knew gravitational fields have their own mass-energy and can cause a runaway effect (black holes), but I never realized this could mean more inertia too. Neat! I'm curio
87.
by drjesusphd 8y ago
First of all, a shooting star is a meteor, not a comet. So we can do better, we can recover individual meteorites themselves. A comet looks stationary in the sky when you see one, only moving noticeably day by day, like a fast planet.
88.
by drjesusphd 8y ago
Yes, this is the essence of the Fermi paradox, and it's often overlooked. 100k years is nothing on cosmological scales.
89.
by drjesusphd 8y ago
It's for high-performance numerical work. The language of choice in scientific computing is still Fortran, and for good reason. Julia has become my go-to language for new codes, but Fortran still has its place. In particular, Julia is
90.
by drjesusphd 8y ago
I'm not talking about elementary school, I'm talking about masters or bachelor's level advanced mathematics that has nonetheless been established for decades or centuries. All I'm saying is that teaching and researching

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