evanb

64 ms·

721.
by evanb 9y ago
Lattice QCD does not rely on perturbation theory, and so it doesn't suffer from a combinatorially explosion in the way you think. However, we do attempt to perform many-millions-dimensional (scaling with the spacetime volume grid size
722.
by evanb 9y ago
First-principles predictions of properties of baryons are only in their infancy. Even the best lattice QCD calculations of mesonic properties at the physical pion mass are good to 1 part in 10^(4ish), nothing approaching the accuracy neede
723.
by evanb 9y ago
Yeah, I went straight to the static solutions for simplicity of discussion. From the outside, though, is it even in principle possible to tell whether a BH is a stellar-collapse Bh or if it's an eternal Schwarschild vacuum BH? Now we
724.
by evanb 9y ago
I thought your other answer was great!
725.
by evanb 9y ago
> There's no "purely gravitational object" it only "looks like that" from behind the event horizon It depends on what framework you're working in. If you're working in general relativity, there's
726.
by evanb 9y ago
Maybe I should be more clear: at least in the generally relativistic conception of gravity, all of the mass of the black hole "comes from" the warping of spacetime already. That's why I keep dancing around the question of wh
727.
by evanb 9y ago
The answer is "by the processes of general relativity". When things fall "down" their potential energy is lowered, so they get faster. When mass-energy accelerates it emits gravitational waves, in much the same way whe
728.
by evanb 9y ago
When an apple falls to the earth, by what process is its potential energy converted to kinetic energy? Gravitational processes alone. Apple-earth collisions primarily radiate apple sauce, black hole mergers primarily radiate in gravitation
729.
by evanb 9y ago
I guess I cannot rely on a widespread knowledge of the history of mathematics :( Still, I thought this line was famous "enough".
730.
by evanb 9y ago
Indeed, the reason most objects seem to be neutral is because of how strong the electromagnetic force is! Were it weaker it would be much easier to separate charges on longer length / time scales.
731.
by evanb 9y ago
I haven't thought about it carefully, but since magnetic fields don't do work, my initial reaction to your example of iron near a magnetar is surprise. But, I also expect that the iron magnetizes in a strong field. Wouldn't
732.
by evanb 9y ago
> Unfortunately, there’s not an easy path to become an expert. One just has to dig in and learn from the ground up. Indeed, there's no royal road to geometry!
733.
by evanb 9y ago
You dropped a bunch of important squares... E^2 = m^2 + p^2 does not simplify to E=m+p.
734.
by evanb 9y ago
A sentence where you begin parsing one way, find it it impossible to complete, and have to backtrack substantially (so that the intended meaning changes drastically) is called a garden path sentence https://en.wikipedia.org/
735.
by evanb 9y ago
An amazing long-form article on these twins from the NY Times: http://www.nytimes.com/2011/05/29/magazine/could-conjoined-t... And a previous CBC documentary is on YouTube: https://www.youtu
736.
by evanb 9y ago
It seems like you're confused about zero-temperature quantum mechanics. Even at absolute zero, the electrons do not 'fall into the core'---they sit in the orbitals---except at extraordinarily high pressures/densities wh
737.
by evanb 9y ago
I think the issue is that, assuming the particle is alone or only elastically bouncing off of its container, E(x) is a constant E in which case (let's assume no internal degrees of freedom) the configuration contains only position and
738.
by evanb 9y ago
"Scott", or "Aaronson", but not "Aaron".
739.
by evanb 9y ago
This reminds me of dual photography, where one can recover hidden images from diffuse-diffuse light transfer. video: https://www.youtube.com/watch?v=p5_tpq5ejFQ page: http://graphics.stanford.edu/papers&#
740.
by evanb 9y ago
Gyros aren't the axiom, they're a theorem---the axioms are Newton's laws of motion.
741.
by evanb 9y ago
This is the first observation in gravitational waves and light. Two other relevant pages: https://www.ligo.caltech.edu/page/press-release-gw170817 http://www.ligo.org/detections/GW170817/press
742.
GW170817 First observation of gravitational-waves from neutron stars inspiral(ligo.org)
2 points by evanb 9y ago|1 comments
743.
The Father of String Theory(nextact.ft.com)
2 points by evanb 9y ago|1 comments
744.
by evanb 9y ago
The measured strain corresponds to a length distortion MUCH smaller than the width of one atom. An atom is about 1 angstrom in linear size, while a proton is 1/10000 that. The measured distortion corresponds to a distance smaller tha
745.
by evanb 9y ago
Or something like citizens-uploaded-content.gov
746.
by evanb 9y ago
And the paper: https://arxiv.org/abs/1708.05256
747.
NERSC Scales Scientific Deep Learning to 15 Petaflops(hpcwire.com)
2 points by evanb 9y ago|1 comments
748.
by evanb 9y ago
Isn't "athelas" Tolkien-inspired? The Tolkien estate isn't super friendly with regards to this kind of reference. Try to find out how much Palantîr paid for an agreement with them (my understanding is that it's a
749.
by evanb 9y ago
LIGO didn't announce because they want to be sure. But one of the most valuable aspects of LIGO is as a trigger for optical astronomy of transient, time-sensitive events. So, when they see something, they have to tell a wider astrono
750.
by evanb 9y ago
Also along those lines: Two notes on notation, Knuth, https://arxiv.org/abs/math/9205211

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