chunky1994

I'm in complete agreement. The fact that he entirely glosses over there existing a field like algebraic topology with tremendous application to physics shows the author has little understanding of what he's writing about when it comes to physics.

This is almost exactly the point addressed in Dr. Ernst Stuhlingher (then the associate director of NASA) in this elegant response:

http://www.lettersofnote.com/2012/08/why-explore-space.html

Which was written to a Zambia based nun who asked how this funding could be justified given the numerous starving children she saw everyday.

It's rather amusing that the author assumes that non-associtiave objects are "weird" for physicists (or at least that was my reading), since the velocity addition formula is in general non-associative and that has been extensively studied.

(I remember three separate occasions in my undergrad particle physics class where we actually went through all the calculations involved with the velocity addition formula and finally saw that SOL was wacky).

https://en.wikipedia.org/wiki/Velocity-addition_formula

I wonder if that is uncommon or if the article is just a bit ungenerous towards our understanding of non-associative objects.

This is a fantastic comment. To provide some anecdotal evidence (which I realize isn't much) I can compare where I grew up (Urban India) vs where I went to University (Urban North America) and can see some Stark differences.

There is a much more safety and risk averse culture here for kids growing up and there is an epidemic of over policing of children. Back home, I could run around and play in the streets without much parental oversight as early as the age of six. All I had to do was get back before dark and my parents made it very clear if I didn't there would be significant consequences (I was never beaten so you can make children understand it without the threat of corporeal punishment). However here, CPS can be called if you leave your child unattended in your backyard.

My theory is that since boys hitting puberty are driven towards riskier behaviour thanks to testosterone (they just have more physical energy than girls that needs to be expended and mundane activities rarely suffice), this policing culture that no longer fits that style of exploration takes it upon themselves to neuter young boys. It's a sorry state of affairs, but unfortunately I don't see a way to fix it without getting mired down in identity politics

It looks like someone flagged the story unfortunately. It dropped like a rock from the front page. It really is an excellently written piece

I haven't touched this stuff in a while so take this with a grain of salt.

This is good progress since it's about an order of magnitude faster for operations than previously constructed CNOT gates, however it still has many caveats for a semiconducter-like leap towards real quantum computers:

a) Low temperature bound for the level of fidelity they want

b) Doesn't allow us to engineer quantum chips of more qubits efficiently since the decoherence between quantum dots is still a major issue.

c) The science journalism title is a bit misleading. While this happens in a silicon structure there is nothing new about it, what's new is that they managed to use the driving resonance to control the dephasing during the gate operation.

The problem is that the gravitational infinities one gets in QFT are non-reonormalizable. Renormalizable theories must follow a very strict criteria (and even then they are rather difficult to grasp if you don't really put a lot of thought into it).

The folks over at anonymous were bombarding the site according to some of the shadier 4chan boards.

I do agree that time dilation occurs, what I disagreed with/corrected was with this: it could travel almost any distance before decaying, which I took to imply that the lengthening of particle lifetimes was not measurable in the way that you just pointed out.

In retrospect perhaps the parent comment was saying theoretically it could travel any distance which is true, but doesn't really help in estimating whether it could clear nuclear radii or not.

Actually what the parent comment said would be correct. Time dilation and length contraction do not arbitrarily change the proper distances that particles travel at near light speeds.

As observers, the detectors would see precisely what we expect if we calculate the distance using the detector's proper time when compared with the distance we experimentally measure.

It's more that we don't have strong enough decision making computers/algorithms to rival a human's capabilities in cases where the action (in this case not having lots of weapons but apparently only one being launched) isn't exactly a binary decision. A computer could theoretically have advocated that this wasn't an actual nuclear launch, but the only way that would happen is if a programmer had been clever enough to have written an algorithm to account for the situation when writing the transcription machine.

A human can currently do a much better job when the outcome is that millions of people die , especially if its a sensor error. That's not to say that humans are infallible, just that we do not currently have the level of AI required to replace one.

I think that example is a bit unfair, teaching really isn't scientific when you get to the core of it. You cannot expect professors to be able to conduct double blind studies with student grades and so a more overarching non-scientific discussion is probably more amenable to actual improvement in performance.

> gravity is so admittedly poorly understood

Gravity as a force/phenomena in space on its own is actually very well understood. In fact it's possibly one of the most well understood theories we have in physics because of general relativity. However, at a particle scale we lack the understanding of how gravity would work.

Dark matter is the collective name for whatever "stuff" exists in the universe that we predict it should have, however because it is noninteractive in any way other than exerting a gravitational pull (it accounts for a lot of astrophysical observations that otherwise are bewildering given what we see in the universe). We know it should exist, we don't know what it is and can barely understand its current properties. So indeed, it is quite possible that it might be Aether-ish if we end up finding something else that explains our current observations or a drastic overhaul of how gravity works at large scales (the latter being very unlikely because of how well GR has stood up to experimentation so far).

That's actually not true. git-pull (which is where the pull request comes from) is in the git manpages. Specifically it is: Fetch from and integrate with another repository or a local branch. Which is basically a git fetch and merge from the submitters repository to the repository they are submitting to.

EDIT: Admittedly if you are talking specifically of the request part, then you are correct. However the name comes directly from git's pull command which is a feature of git.

I really do enjoy this, thank you very much! I may try and do a writeup of the possible physics at some pint with your permission, would that be okay? (Also Uwaterloo represent!)

If it was possible certainly, however a lot of european universities especially in the Schengen region require the knowledge of a language other than english (whether German, Swiss etc.) for effective learning (a language which is probably not as common in a non-Schengen area).

Furthermore visa and citizenship requirements probably preclude the same for international students, however I'm not too well informed in that regard.

Some context here:

1) This is for one, 4 month term at university in Canada (uwaterloo specifically) for an engineering degree. Other degrees are lesser in cost (math is similar, which includes CS) A lot of the miscellaneous fees drop off in the second term (you only pay them once per year).

2) These are domestic fees, international fees are much higher (approx 3x) but still only around 1/3rd of the international US tuition.

3) This includes residence and food in it.

4) Co-op fees are paid for every term before you go on co-op, engineering typically has 6 terms before we graduate.

5) It is FAR cheaper to live off campus and cook.

6) It is still far cheaper than the US universities (even if you're in state)

EDIT: The image for the fees was for one 4 month term.

This isn't true for waterloo. (Bo was probably in 4 stream.) We only pay for the terms before we actually go onto co-op.

EDIT: As he points out below, it's different for different programs (even within engineering some pay 2 terms before their first term and some pay 1 term before. However the fees continue onwards for every term that the student is not in co-op).

While I admit the government is trying to censor (or was, I've yet to see any evidence of this from the current government) certain politically critical articles etc. and I am unaware of the true extent of the CMS, the part about the UID program seems rather sensationalist and fear-mongering, since the primary aim of the UID program is the ability to identify the citizens of India similar to the US social security number system.

The reason we need this biomertic data would be to ascertain the identity of over a billion people where unique names, places of birth and the existence of birth certificates aren't the norm, not in order to constantly police the populace.

If you could make more explicit the problems with gathering biometric data of citizens, (which shouldn't be used for security purposes anyway) then I'm sure I would get a better understanding of your position.

When you say QM is deterministic except for the Born rule, I would add that a lot (almost all) of QM is based off of the Born rule [1], so as to avoid potentially misinforming the unfamiliar reader.

[1] The Born rule in QM is the rule that allows us to calculate the probabilities that a particular experiment would have a given outcome. http://en.wikipedia.org/wiki/Born_Rule

Well that's not necessarily true in the sense that we have no idea what was before the big bang. Time as we know it did not exist before the big bang, however there could've been almost anything before and it doesn't affect our universe. (Except in certain theories where brane collisions could possibly have driven the big bang, in which case the specific type of collision does matter etc.)

While I agree with what you are saying, I'd like to add a bunch of addenda (caveats?).

The Higgs mechanism was one possible model which the standard model required, the others have now obviously been disproven thanks to the LHC. If no one had proposed this particular model, we'd still be wondering how fundamental particles gained mass and have another unexplained experimental result with the peak at 125 GeV from the data at the LHC.

Similarly, GR and QM are both extremely well tested, however GR has dark matter and energy to deal with, and we still have no real idea what that is. This could potentially point to GR being wrong, however none of us are able to come up with another theory of gravity that could incorporate this and be better than GR at this stage. If a theory of quantum gravity (or just gravity) came along that could explain dark matter quite effectively then it would be hailed as a better theory than GR.

The reason string theory and loop quantum gravity are considered completely speculative is because their predictions are so far beyond our grasp that even in the relatively far future we still have no way of confirming or denying either of them. Had they predicted things that could've been confirmed within the next century or so, I'm sure we'd all be rallying to try and confirm them. They aren't speculative so much so because we don't know which of GR or QM is wrong, but because their testability is quite precarious at this point.

I highly recommend the intro to data science course on coursera: https://class.coursera.org/datasci-002

Even if you have only a little programming experience if you spend a fairly reasonable amount of time on this you'll come out with a lot of practical knowledge which will allow you to jump into more advanced courses. (It has a bit of python, SQL and R).

As far as I see it, every proof I have ever encountered has been of two types:

A => B, or A <=> B.

The first of which has the following structure: A: Given conditions (a,b,c,...) are true; B: We can say (..., x, y, z) are true.

The second having a structure: A: Given conditions (a,b,c,...) are true; B: We can say (..., x, y, z) are true.

AND

B: Given conditions (..., x, y, z) are true; A: We can say (a,b,c,...) are true.

The easiest (and quickest) way for me to parse proofs given the above representation is by ensuring I know what the conditions (a, b, c, ...) mean and how removing one of them changes the proof, therefore ensuring I know exactly how each condition contributes to the final result.

(This is probably what he was talking about in his second point)

Are you guys open to hiring interns?

The reason that comment was voted down is very likely its rather unnecessarily adversarial tone. It takes very little effort to have the same content and be polite while expressing it.

My only wish is that articles like this had citations for some of the things they are saying. (For example: The amygdala develops early compared to the pre-frontal cortex, how early? At what age?)

I couldn't find any papers on the subject and would be grateful if someone more familiar with biology would point me to them.

> No matter what system you set up, if you're cutting three boards to build a triangle the length of the big one is absolutely defined by the length of the other two, assuming Euclidian geometry. The symbols (a, b, =, c, +, superscript 2) are all totally arbitrary but if you're working with three boards there is absolutely an intrinsic correctness to the Pythagorean theorem.

This is only true because we are assuming Euclidean geometry, and as I had said earlier, this implies that we can logically conclude these facts because mathematics is logical and internally consistent given these axioms, so we cannot say that they are intrinsically true; that would require us to know without a doubt that the axioms are correct. Since we can use Gödel's incompleteness theorem to show that our axioms are necessarily assumed, we can say that we do not know if they are correct or not, only that assuming they are, we can make a lot of really good predictions about the world around us.

> The amazingly cool thing is that our system is so good that we can use our abstract symbols to make predictions about physical laws and they actually come out to be true!

This is definitely amazing, however it does not mean that our system is necessarily correct, in fact it is demonstrably lacking in Quantum mechanics for example, where we need to renormalize infinities, which makes almost no mathematical sense whatsoever, but we do it because our experiments tell us that if we do, we can make predictions about how things work.

> I would argue that all of physics is basically "math that's a fundamental truth of the universe".

I agree with the spirit of what you are saying here, but think I would phrase it in the following way: I would argue that physics is basically fundamental truths about the universe that we can describe to the best of our ability using an abstract framework such as math. The fact that we can do that does not mean mathematics consists of these fundamental truths.

EDIT: Modified last paragraph to be slightly clearer.

For questions about mathematical correctness I highly prefer wikipedia. To me it's far more specific and clear, while the original article makes rather short work of proofs.

When it comes down to questions that involve first principles, I would much rather have rigor over a less time consuming but potentially wrong understanding of the material, and wikipedia does quite well in providing that rigor.

What exactly do you mean by fundamental truths here?

Mathematics is an internally consistent (for the most part) logical framework that is extremely powerful in expressing our knowledge about the world.

However, that doesn't mean that there is some intrinsic correctness about it or its concepts.