3,059 reputation
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bio website about.me/danieldf
location Providence, RI
age 38
visits member for 4 years, 1 month
seen Aug 26 at 20:38

Apr
17
comment Who works professionally on reformulation of QFT?
It's very frustrating to sit down and take the time to write a meaningful and relevant answer (including refs to original work), just to get downvoted without a single comment explaining the reasons of such action. Where i come from, this has a very clear name: trolling. Maybe this is the tip-of-the-iceberg of having a question-&-answer site for topics such as Physics: to be trolled by folks that don't understand what's written. :-P
Apr
13
comment Who works professionally on reformulation of QFT?
@Vladimir: regarding your comments about regulators… i think there's something missing, for the VOA (or OPE) uniquely determines the interactions of the theory: this algebraic structure encodes the interactions. What you described above is just a rudimentary way of saying the same thing.
Apr
13
comment Who works professionally on reformulation of QFT?
@Vladimir: I know people trying a few different things, but some (if not most) of them requires much more 'hardcore' math — which you have already dismissed above. In any case, the Clay Institute is offering a big prize for whomever can pull this off…
Apr
13
comment Who works professionally on reformulation of QFT?
@Vladimir: both of your points above — as expressed — have to do with the same question, the so-called UV-completeness of the theory. This, in turn, is related to Renormalization, VOAs, and so on.
Apr
13
comment Who works professionally on reformulation of QFT?
Regarding your first comment above, i explicitly addressed it in my "PS" — in fact, this was the raison d'être for my editing my original answer in order to add the "PS". So, i simply don't understand what you meant. Further, "these points" are not "quite distant" as you seem to think: they are $1/\Lambda$ from each other, where $\Lambda$ is the energy scale of your problem: the more energy, the less apart they are.
Apr
3
comment What are some approaches to discrete space-time used in modern physics?
@Deepak: don't sweat it. Living and learning…
Apr
1
comment What are some approaches to discrete space-time used in modern physics?
@Deepak: don't mistake your lack of knowledge for "random facts": the fact that you can't put these arguments together and understand my points says absolutely nothing about their validity (it only speaks about you). It's not my fault you don't know certain aspects of QFT: i even provided a reference that expands on some of my points (on top of giving you more references to clarify further doubts). I have been very honest and forthcoming, but can't fit in ~350 characters what i understand to be the answers you're looking for.
Apr
1
comment What are some approaches to discrete space-time used in modern physics?
@Deepak: "(…) they are as silly as these two." I haven't used adjectives to characterize your comments so far and i'd have appreciated you keeping this discussion at the Physics level. However, i understand your inability to do so, granted that you don't even appreciate what a 'Cauchy problem' is. So, if you want to keep on trolling, go right ahead — i have better things to do.
Mar
31
comment What are some approaches to discrete space-time used in modern physics?
As for your other points, suffices to say that QFTs over curved backgrounds are a hairball. And i would love to see you do QFT over a de Sitter background (as opposed to its more famous cousing, anti-de Sitter): can you define the Cauchy problem for a simple (bosonic, spin 0 — free scalar; or maybe even $\phi^4$) QFT over de Sitter space? If you can do this, would you be able to do very same for Gauge Theories (Yang-Mills)? Maybe our definitions of "frontier research" are slightly different...
Mar
31
comment What are some approaches to discrete space-time used in modern physics?
@Deepak: I really don't intend into dragging this discussion, so i hope this short version of my answer will satisfy you: you can read about wave-particle duality in Penrose's tome, The Road to Reality, chapter 21, in particular in section 21.5. As for QFT, it creates and destroys wave-functions, thus clearing the confusion on the spot. Now, if you want to call the measurement problem by "wave-particle duality", that's your personal choice, but not the community's.
Mar
29
comment What are some approaches to discrete space-time used in modern physics?
@Deepak, cont'd: with that out of the way, let me ask you this: Does QFT resolve the so-called wave-particle duality or not? What is the definition of the information theoretical aspect of the unverse? What are the domains of validity of QFT and how would this fare when compared to a possible theory of quantum gravity? Thinking about these questions will definitely lead you into what my reasoning was to answer these questions.
Mar
29
comment What are some approaches to discrete space-time used in modern physics?
@Deepak: I know perfectly well what i'm talking about and assure you there's absolutely no misconceptions anywhere in my answer. Having said that though, you don't need to take my 'assurance' as any form of guarantee, but if you're going to make such a strong criticism, it'd be good form for you to point out the differences, the misconceptions you claim to exist.
Mar
29
comment
What is your controversial General SE Theory?
Mar
21
comment Canonical momentum operators in curvilinear coordinates
@MBN: the last equation in the question has an inner product, which led me to believe that i could make some "general Physical assumptions", such as the existence of a metric and of a metric-compatible connection.
Mar
20
comment Does Heisenberg's uncertainty under time evolution always grow?
@Marek: the point was made explicit by Qmechanic, in his answer above. If you apply what i said in the Schrödinger picture, you get evolving states whose magnitude is always bound by the Mean Value Theorem. (If we were talking about bounded operators, this could be made rigorous with a bit of Functional Analysis.)
Mar
19
comment Why do people still talk about bohmian mechanics/hidden variables
@MBN: It's good to have a diversity of views and opinions… but Science is not exactly 'democracy', in the sense that there's a clear direction which is preferred: you can't choose to not "believe" or to have a "diverse opinion" about $2+2$; you can't have a "loud vocal minority" that doesn't endorse nor subscribe to basic arithmetic. On the other hand, it does take time to establish some facts across a large community, and all one can do is keep on teaching.
Mar
19
comment Why do people still talk about bohmian mechanics/hidden variables
If the answer is informative, hopefully there's something to be learned from it — in which case my opinion is unnecessary: as the Marines say, "everybody has one and they all stink". People do stuff for all sorts of reasons… but, with some luck, after some time these things get sorted out in sciences…
Mar
7
comment An alternative, algebraic way to introduce interactions. Are there other ways out there?
@Peter: can you expand a bit your comments about the Buchholz-Lechner-Summers? I'm not sure whether we're both make the same reading of that paper.
Mar
3
comment How does gravity escape a black hole?
Sure, you're probably right. But, i'd rather not use any more than i have to (in terms of assumptions or extra estructure): if you can answer with some sort of 'minimum' set of assumptions, why 'complicate' the problem — and have to deal with the consequences of said 'complications' later? ;-)
Feb
15
comment How does gravity escape a black hole?
@Daniel Grumiller: In more general grounds, you don't need to agree with nor anyone else. But, in this particular case, the reason is pretty straightforward: because it's possible to answer the original question without having to talk about a possible quantization of GR. To appropriately and scientifically answer the original question, taking gravitons into account, sooner or later one would have to compute the scattering of light by gravitons (and vice-versa), which would immensely complicate an otherwise simpler answer.