David Zaslavsky

27,431 reputation

448112

bio	website	ellipsix.net
	location	State College, PA
	age	27
visits	member for	2 years, 6 months
	seen	1 hour ago
stats	profile views	7,319

I'm a fifth year graduate student in physics at Penn State University, doing research in high-energy particle phenomenology. I also have a hobby interest in computer programming.

You can find me on Google+ or Twitter. Or check out my blog and personal website!

For matters not related to Stack Exchange, I can be contacted by email at stack+physics@ellipsix.net.

	27,431 reputation	bio	website	ellipsix.net	visits	member for	2 years, 6 months
448112 badges		location	State College, PA		seen	1 hour ago

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2h	revised	Is it intuitive that the conserved quantity from time symmetry is what we know as energy? improve title
4h	comment	Is there any place you can safely skydive without a parachute? Maybe the question could be rephrased to ask under what conditions, if any, a person would be able to do this.
5h	comment	How fast could a football drop? The problem is not about whether it's a homework question, it's that you haven't shown any effort to work on the problem yourself, and that you haven't picked out the part you're confused about. Don't ask us to solve a problem for you, ask for a clarification on a concept.
6h	comment	Electric dipole moment, which charge is the $q$ for? @Anuar that should be an answer
9h	revised	Physical interpretation of changing variables $S(T,V)$ to $S(T,p)$ put equations inline
11h	comment	How fast could a football drop? Hi Alex - this is a site for conceptual questions, not for homework help. If you edit the question to explain what you've tried and what concept is confusing you and ask about that, I'll be happy to reopen it. But just giving up and saying you're unable to solve it without trying anything is not enough. See our FAQ and homework policy for more information.
11h	comment	Violation of Newton's 3rd law Is your question about colliding particles, or is it about two objects attracting each other from a distance?
11h	comment	Diameter of the universe Actually the radius is more like 46 billion light years, though I'll leave it to a specialist to explain why.
11h	comment	physics (measurement) Hi Maryam, and welcome to Physics Stack Exchange! This is a site for conceptual physics questions, not for homework help. If you edit the question to show what you've tried and where you got stuck, and to ask about the specific physics concept that is giving you trouble, I'll be happy to reopen it. See our FAQ and homework policy for more information.
11h	revised	physics (measurement) edited tags
11h	revised	Does an elliptical orbit of a satellite maintain its orientation as the Earth revolves? fix title and add alt text
1d	answered	Why doesn't this equation for orbital motion change with position in the orbit?
1d	revised	Why doesn't this equation for orbital motion change with position in the orbit? edited title
1d	comment	What is the meaning of the concepts of “operator mixing” (and anomalous dimensions) @Dilaton "an example of what one wants to better understand from knowing these concepts" What concepts? That is the key issue. Right now the question asks to know "about the idea of 'operator mixing' and...anomalous dimension" but that is not a concept. What about operator mixing and anomalous dimensions does user6818 want to know? The definition? What they are used for? Some particular aspect of how they are used? That is what we need to wait for clarification on.
1d	comment	What is the meaning of the concepts of “operator mixing” (and anomalous dimensions) @Mitchell this doesn't ask for a definition, it asks for an explanation, but it is not very specific about what it wants explained. Among the downsides of leaving it open are (1) that people use this as a justification to ask other unfocused questions, and (2) any answers posted may no longer apply later when the question is improved, and (3) it diminishes the site's usefulness as a place to find answers to practical questions.
1d	comment	Specular intensity Hi Super poop, and welcome to Physics Stack Exchange! This is a site for conceptual questions about physics, not general homework help. This question isn't asking about a concept, and it also seems more about computer graphics than physics. If you are confused about a specific physics concept, edit the question to ask about that and if it's appropriate I'll be happy to reopen it. See our FAQ and homework policy for more information.
1d	revised	Specular intensity fix formatting
1d	comment	What is the meaning of the concepts of “operator mixing” (and anomalous dimensions) @Dilaton for recent questions I leave comments, but not always on old ones. In general if an OP of an old question comes back and sees the question closed, and would like to know how to fix it up, they can always ask. Anyway, this question is still somewhat unfocused. Is it asking what operator mixing is? Or how equation 12 in the second paper was derived and what it means? Or how it relates to anomalous dimension? Each of those is a separate question, and thus we need some clarification from user6818 about what the intent is here. (Your edit does help a lot though.)
1d	revised	Lowest attenuation at 1550 nm for link lengths in 30-50 km range edited tags
1d	comment	Difference between velocity vectors, relative speed Yes, it's clear that they are velocities, but how exactly is $V_B$ defined? Velocity of what (presumably object B) with respect to what?