* Posts by tfb

404 posts • joined 11 Jan 2010

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Tesla fingers former Gigafactory hand as alleged blueprint-leaking sabotage mastermind

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Boffin

Re: Energy "storage" via existing hydro

This does not work outside special cases -- Norway being one such of course! There's not enough hydroelectric capacity worldwide and there essentially can't be enough because there aren't enough suitable places to put huge volumes of water high up which are reasonably near other places much lower down, short of civil engineering on an implausible scale.

Note I'm emphatically not against hydroelectric power (or any other kind of renewable power), or against this technique being used when it can be used, such as in Norway.

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Re: Security

The answer to this is don't consider people trustworthy. Instead you control and audit access to systems and data: no-one has access to sensitive data outside some kind of authorisation, authorisations get signed-off by people who don't have conflicts of interest, access is logged in a tamper-proof way and so on. The access logs are cross-referenced against access requests and so on.

This doesn't stop all attacks: nothing can stop all attacks. But it does make them significantly harder. Some people, financial institutions, for instance, are already doing some or all of this and are working hard on doing more of it (I know this because I have worked on systems like this for these places). But most people seem to just treat it as too hard.

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Re: Security

That's why a huge part of the security of computer systems is controlling who has access to what. If some technician has access to critical data without controls then the security of the system has failed.

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Alien

Re: Security

Brcause they likely don't care. We've reached a point where some contractor for the NSA can acquire a vast trove of sensitive information, and almost no-one asks how the NSA, the people who wrote the fucking orange book, could be running computer systems where it is even possible for this to happen. Computer security is a lost cause, because no-one, actually, cares.

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Re: Security

My point was really that if someone can get malware (which seems to be the claim here) into something involved in designing spacecraft and, for instance, adjust design parameters then quite bad things could happen to the spacecraft.

But this was wrong: if a rocket blows up &/or fails in a way that kills its crew (I know, they are unmanned so far but not presumably in the future) then it's a very visible thing which kills a few people; if someone can do the same thing to a car design then it's a probably less visible thing which could kill a large number of people. So Tesla's security matters more & I was wrong. Or, well, it would matter more if they could actually manage to make any cars.

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Security

So here's yet another case of a relatively junior person acquiring and running off with a large mass of sensistive data. Because secure computer systems are, clearly, not a thing you need to care about. Let's hope SpaceX are doong a better job, but I bet they're not.

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There are these fantastic things which can store electricity so you can store it up when the sun is shining or when demand is well below supply from your nuclear power station and then use it later. I think they're called 'accumulators' or something like that. I've heard rumours that these new-fangled electric cars may contain them: I'd assumed they were loke trams used to be and ran from overhead wites but apparently not so.

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Visa fingers 'very rare' data centre switch glitch for payment meltdown

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Presumably the primary failed but said that it was working, thus preventing the secondary from picking things up until someone realised the primary was confused about its state and killed it. This is a failure mode l've seen with SAN switches (so different case) and it can be hard to debug, especially given the terror associated with killing the thing and possibly finding out you killed the working one.

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What's all the C Plus Fuss? Bjarne Stroustrup warns of dangerous future plans for his C++

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Re: I am scared of the pressure to add [...] features to address immediate needs and fashions

On the other hand, I could tell an opposite story if I wanted to do some large array-bashing numerical-model stuff in Python or Perl. In Python there's NumPy and an entire culture built on top of it, in Perl there's ... what?

Note I hate Python (though I have to write it) and am secretly rather fond of Perl (which at least has variable scoping rules which don't make me want to sandpaper my fingers off): I'm not trying to support either language.

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Re: Design by committee

I think the rot in C++ started when someone thought it was reasonable to overload the bitshift operator to do I/O. I mean, seriously? (Yes, I know why that happened, but it doesn't help).

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Da rude sand storm seizes the Opportunity, threatens to KO rover

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Re: God speed little robot

Apart from the weight / complexity thing, imagine what happens if, while the panels are shut / upside down, something goes wrong.

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Boffin

Re: A place in history

Not everything is computers. The whole wheels, solar panels, drills, science experiments, being designed to work in a fairly hostile environment thing may count for a little more than the processor. Also being strapped to the top of a fucking great rocket (also largely not made of computers) and sent to Mars helps.

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Re: A place in history

Spirit & Opportunity weren't launched in the 1960s, but 2004: attitudes were not that different whn they were designed & launched to what they are now, apart, perhaps, from some of the really weird extreme political shit.

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UK comms firm Gradwell quits cloud land after 'strategic review'

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Re: Well let's see 20 years and £7.34m in turnover.

Why is that underwhelming? How many small companies survive for 20 years? I suspect it's only underwhelming because somehow we expect all startups to turn into Google.

Note, I'm not a Gradwell customer (I was once) or in any way involved with the company.

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NASA makes the James Webb Telescope a looker with a heart of gold

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Re: Ssshhhhh!

Somehow I doubt that Trump has the mental bandwidth to sustain distinct public and private personas. He lives in the tacky golden palace: whether his wife does is a different question.

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NASA finds more stuff suggesting Mars could have hosted life, maybe

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Re: And the remnants had fled to Earth.

Yes. Quatermass and the pit, I think. Very frightening.

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Re: Suggestive, but nothing more

If the universe is flat (which it appears to be) then it is indeed really big: it's infinite in fact. Sadly only a finite amount of it is visible to us.

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Re: Suggestive, but nothing more

I don't think anyone has any real expectation of anything beyond single-celled organisms, let alone things with bones, which are relatively recent on Earth.

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Mirror mirror on sea wall, spot those airships, make Kaiser bawl

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Alien

Naval gazing

I am not sure about this but I suspect a lot of the reason for Zeppelin attacks on the north was naval: if you can attack Sunderland, especially if you can do so with less warning than it takes a dreadnought to raise steam (which was hours) then you can't keep the Grand Fleet -- or even a significant detachment of it -- that far south without risk of loss. This helps to ensure is that they end up in Scapa Flow with some down at Rosyth, making the North Sea safer for the High Seas Fleet (which in turn could then raid the same ports, as they did). The Germans desperately wanted to avoid a full-scale fleet action, which they assumed they would lose, which would be very bad for them. I don't think anyone expected Jutland to be so inconclusive, although if we had been coming from further south and thus met the HSF earlier in the day it probably would not have been.

A mad alternative theory for these mirrirs might be that they were intended to listen for ships (I'm sure this is wrong: they were obviously built to listen for Something Nameless rising from the North Sea.)

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Four hydrogen + eight caesium clocks = one almost-proven Einstein theory

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Mushroom

Re: Gravity is an attachment force

Who was it who wrote 'you with your head proverbially buried in your own version of apartheid having been taught by rote' I wonder. Oh, it was you: you're a crank and a liar. Just fuck off.

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Alien

Re: Gravity is an attachment force

Sigh, this is why I need not to read comment threads: I can never give up.

Just to be clear: I did not say anything about your education -- I have no idea what qualifications you have or don't, and nor would I regard lack of formal qualifications as any kind of indicator of how smart or otherwise someone is. What I gave was a plan of attack to get your ideas taken seriously, which plan of attack is, in essence, 'put in the hours, and get evidence you have done so': the qualifications are that evidence, no more and no less. You could not know this but I failed in this process of putting in the hours: I'm not sneering from my ivory tower.

However all that was before your last two comments, in which you've made it very clear that, sadly, you are indeed simply a crank. Your final paragraph: 'You live within a steady state universe that is entirely electromagnetic and Newtonian [...]' makes that abundantly clear. All three claims in it are demonstrably false and have been shown to be false both in many experiments and also, in the cas of the scond two, just in the workings of a huge number of engineered objects. This kind of mad crankery is, of course, why people won't listen to your incoherent nonsense.

I apologise for ever responding in the first place: it is always a mistake to try to help cranks. I should know that by now.

OK, I really am done now, I have horses to photograph.

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Boffin

Re: Equivalence orinciple (was @ Adalat)

I know you've given up but I realised this last night I thought I would add it in case anyone else reads this, as it's neat.

There's a variation on the mountain-at-the-end of the track scenario. Instead of letting the car move freely down the track, tie it to the track. Now the ball-bearing will, of course, roll down the car, and in fact this case is indistinguishable from the case where the car is being towed down the track, locally. And again you can stop the ball rolling by tilting the track, and when it's tilted it is now, again, horizontal, because the presence of the mountain has changed what horizontal is locally.

And that's the thing: all these variants come down to the same thing: the direction (and magnitude) of the vector describing the acceleration due to gravity, as measured from the car, is changing. All the apparent differences come about because the car is constrained to move only along the track.

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Mushroom

Re: Gravity is an attachment force

The amateur thing may have been true a century and a half ago. I can't think of any examples since 1900or so (and no, Einstein wasn't one). Thanks for accusing me of bigotry: a nice touch. I can see why no-one will read your book: you're not only a crank, but one who thinks the right approach to disagreement is personal attacks. Bye.

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Boffin

Re: Gravity is an attachment force

No one wants to review it because professional physicists (and I am sure other scientists and mathematicians) are continually bombarded with papers claming to overturn physics / solve quantum gravity / prove that P=NP / solve the halting problem / provide a theory of everything. If they reviewed even a tiny fraction of these then they would stop doing any useful research, so they don't.

Instead there is a very well-understood way of getting people to pay attention to your theory: you do a degree, a PhD, a postdoc, and start publishing papers on it in peer-reviewed journals. Yes, it's hard work: such is life.

Always remember: physicists accepted quantum mechanics and are seriously thinking about theories which require 10, 11 or 26 dimensions: they are not ignoring your theory because it is too whacky.

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Re: Equivalence orinciple (was @ Adalat)

The point is that if you can't look outside the car you can't tell if the track is horizontal or not: there is nothing you can do which will allow you to distinguish running at constant speed on a track running up hill or being accelerated by the locomotive on a horizontal track. That's what I was trying to get at by the whole tilting thing: thinking of the rails running uphill is better really. And that fact (that there is no experiment you can do to distinguish those two cases) is the weak equivalence principle: the strong equivalence principle says that those two cases are therefore the same: the force of gravity is acceleration.

The equivalence principle really is (as far as we know) correct: if I've failed to convince you that it is then that's because my explanation hasn't been clear enough, and I'm sorry. It's worth (well, I found it worth) spending some time trying to think up experiments that would let you distinguish: you'll fibd you can't

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Boffin

Re: Equivalence orinciple (was @ Adalat)

You can not distinguish between the car being accelerated by a locomotive and the car being tilted (on a planet with a slightly higher value of g). Sorry, that fell between my two points and may not have been clear. You can always know what the acceleration of the car is (normally it is 9.8m/s^2, directly downwards) but you can never distinguish the cause of that acceleration: whether it because you are sitting on the surface of a massive object, or being accelerated by a rocket or a locomotive or some combination of the two as in your case.

A good way to see this is to construct the car such that it can be tilted somehow (put the floor of it on some kind of pivot, say). Now, when it is being accelerated by the locomotive, tilt the floor such that the ball-bearing remains stationary. Now: are you sitting on an untilted car on a planet whose value of g is slightly more than Earth's, or are you on a tilted car which is being accelerated? No (local) experiment you can do will tell you.

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Boffin

Re: Flat Earthers

Here's a nice test for that theory. Take a lump of plasticine and make it into a large, flat shape and weigh it. Now take the same lump and mould it into a tall thin shape and weigh it again. If the weights are the same, the theory is false. You can do a similar experment by weighing people standing up or lying down,

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Alien

Re: Gravity is an attachment force

I've written a book on the life cycle of the venusian mind-worm: I consider myself an expert on the subject.

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Boffin

Equivalence orinciple (was Re: @ Adalat)

So, if you are on your rail car and either you make it a closed car so you can't see the outside world, or you carefully just look at the car and the ball bearing on it. Then:

  • if you see that the ball bearing does not move (or moves at constant velocity, neglecting friction) with respect to the car you can not tell whether the car is stationary (or moving at constant velocity) on the track or is accelerating along the track under the gravitational influence of the mountain, you know that it is not being accelerated by, say, a locomotive, however;
  • if you see that the ball bearing accelerates with respect to the car then you can't tell whether the car is being accelerated down the track by some force (other than gravity!) like a locomotive or whether the car is stationary (or moving at constant velocity) on the track but tilted.

That's what the equivalence between gravitation and acceleration means.

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Re: The article doesn't quite make sense

Neither the falling lift nor the Earth in orbit around the Sun are accelerating (according to GR). In both cases there is no applied force, as gravity is not a force in GR, so the bodies are moving in 'straight lines' through spacetime. Because, in both cases, there is a gravitational field, the spacetime they are moving through is not flat, and the things I called 'straight lines' are better called geodesics, which are the equivalent of straight lines in a manifold (which is what spacetime is in GR) which is not flat. In a flat manifold geodesics are precisely straight lines.

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Boffin

Re: I can easily tell the difference....

Yes, what you are measuring when you do that is (one component of) spacetime curvature, and that is indeed how you distinguish between gravity and acceleration. The key point is 'some distance away': there is no experiment you can do locally (ie at a point) which will distinguish. That's what the equivalence principle actually says.

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Monday: Intel touts 28-core desktop CPU. Tuesday: AMD turns Threadripper up to 32

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Re: Gimme speed

Thanks!

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Re: Gimme speed

That's a nice example! If this was C, I wonder if the spec even says whether two functions which have different textual definitions but which are clones of each other must have different addresses?

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Re: Gimme speed

I believe many compilers also risk the result being wrong, at least in some cases. I read a recent thing on an optimization commonly done by C compilers which turns code with behaviour defined by the spec into code with behaviour not defined by it. Certainly we worry a lot about checking that code gives bit-reproducable answers at high optimization settings, which it does not always do, even in Fortran which has been much more carefully designed for optimization than C.

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USA! USA! We're No.1! And we want to keep it that way – in spaaaace

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Re: Consequences

Apollo was quite a small war. In 2011 dollars, Apollo cost something like $200 billion. Afghanistan cost over $400 billion.

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Boffins quietly cheering possible discovery of new fundamental particle: Sterile neutrino

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Re: I presume that public money is spent on this.

And it can also disappear of course. That's the wonder of currencies: more of them can be made as an economy grows. Imagine a 'currency' where there were only, say 21 million pounds and no more could be made, ever. What happens to those pounds between, say, 1100 and today?

What the original comment meant, of course, is that money doesn't just disappear: it requres a central bank to do that.

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Boffin

Re: But the average density of a black hole goes down with its size.

Well, it's easy to tell that we're not inside a black hole in two ways.

First of all the universe is expanding, not contracting, so if anything it would have to be a white hole, not a black hole.

Secondly it looks the same in all directions, and this would only be true for either a black or white hole solution if we were in a very privileged position (ie at the centre). That seems implausible and I think in either case the universe would look very different if it turned out to be true (ie if we were at the centre it would not look like it does)..

So instead we must be living in some other kind of solution, and indeed we can find such solutions which in general are called Friedmann–Lemaître–Robertson–Walker solutions -- FLRW metrics for short. These describe universes which do look like ours: for instance they are homogeneous (the same everywhere), isotropic (the same in all directions) and either expanding (this is ours) or contracting (this isn't). It's by looking at these, and in particular by looking at their average density, that we conclude that the universe appears to be spatially flat, and hence infinite.

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Boffin

Re: Possibly a Stupid Question...

The equations of GR have, essentially, matter on one side (in fact energy-momentum, which includes matter, radiation &c) and spacetime curvature on the other. So yes, they do strongly constrain the spacetime curvature in the absence of matter. Spacetime certainly can not contain arbitrary ripples or wrinkles, as you claim. However it's also not the case that all vacuum solutions (which is what such solutions are called) must be flat: there are a bunch of different families of them, including, for instance, the Schwarzschild solution and lots of things including gravitational waves. None of these make much sense as a way of explaining dark matter.

(The flip side of this is dark energy, and GR has no problem there: dark energy just appears as a 'cosmological constant' which was initially present in the equations, then removed by Einstein for reasons which turned out not to be very good, and has now been put back. The cosmological constant only explains certain sorts of dark energy and I don't know if what we observe agrees with what GR predicts although I think it does. There remains the problem of trying to understand why it has the value it does, and I think that's a problem.)

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Re: This is not making physics any easier

It keeps them in work.

Not many of them: the great majority of people work on thngs whose fundementals are understood already.

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Boffin

Gravity does act on light, and in particular the energy-momentum of light does curve spacetime. There is a famous idea in General Relativity called a 'kugelblitz' which is that, if you can get enough radiation into a small enough space, then its effect on the spacetime curvature will be sufficient to form an event horizon, and you'll get a black hole, one whose precursor was pure electromagnetic radiation, or light in other words. This is probably unlikely to happen in practice, but itks a very strong demonstration that light does indeed contribute to curvature.

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Re: This is not making physics any easier

Is that right? It smells like it should be, since that kind of collapse is what happens in supernovae, but on the other hand if you imagine turning off the fusion in the Sun what you'd have in the short term would be a core that was just as hot and thus emitting as much thermal radiation, so nothing woukd change, perhaps, except it would slowly start to cool. My argument I guess is that the thermal photons are the radiation pressure and it takes them a long time to fade away. I think that is probably wrong though, and obviously I could find out by reading about it rather than making up handwaving arguments (so in particular I'm not claiming I'm right!).

However it is true that one of the suggestions to explain the deficit of Solar neutrinos was that fusion had stopped, I am oretty sure.

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Big Brother

Re: I presume that public money is spent on this.

You vote for a government. They decide what to fund from taxation. If enough people disagree, another government gets elected. If you want a grey utilitarian nightmare, vote for the grey utilitarian nightmare party who will stop all funding which can not be immediately justified.

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Boffin

Re: This is not making physics any easier

Neutrino oscillation has been known about for a fairly long time. It's a critical result for two reasons.

Firstly it means that the Sun hasn't gone out, which is a good thing for the long-term future of life on Earth. Fusion in the Sun's core produces electron neutrinos, in huge numbers. Based on the Sun's luminosity (ie how bright it is!) we can estimate what the rate of fusion in the core must be, or in fact what the rate must have been some time ago, as the energy from processes in the core takes a long time to get to the surface where we can measure it. Knowing the rate of fusion means we can predict the neutrino flux passing the Earth. From the 1960s it became possible to detect these solar neutrinos, and it became apparent there was a serious problem: there weren't enough, by a factor of 1/2 to 2/3.

There are two possible reasons for this (three if you include experimental error, but multiple experiments saw the same problem). The terrifying one is that fusion could be stopping in the Sun: because neutrinos escape from the core immediately they tell you the rate of fusion in the core now (or a few minutes ago, in fact), while the Sun's luminosity tells you the rate thousands of years ago. So if fusion had stopped, or dramatically decreased, this would explain the result. It would also mean that stellar models were terribly wrong and that life on Earth had no future as the Sun was going out. The other possible reason is neutrino oscillation: the Sun emits electron neutrinos, and we detect electron neutrinos. But if neutrinos oscillate between three flavours -- electron, muon and tau -- then, between being created in the Sun and us observing them, the oscillation would mean we see only about 1/3 of the neutrinos we naively expect to see, as 2/3 of them would have leaked away into muon or tau neutrinos, which we don't detect.

Well, there are other ways of estimating what is going on in the Sun's core, and they predicted that fusion has not stopped. A bunch of other experiments with neutrinos were also done, including some which showed neutrinos produced in the experiment, at known rates, changing flavour. So neutrino oscillation turns out to be the right explanation, and the Sun has not gone out. The 2015 Nobel prize for physics was awarded for this work.

Secondly it means that neutrinos have mass. This is a lovely result because it comes straight from relativity. Massless objects travel at the speed of light, and thus along 'null curves', which are the curves (straight lines in the absence of gravity, curves in its presence) which light follows. But these curves have zero proper length, which means that objects following them experience no time: for a photon, or any other massless particle, everything happens at once. But this means that if neutrinos are massless then they can't oscillate, because they have no time to oscillate as everything happens at once for them: they experience no time between production in the Sun and detection in Earth.

But they do oscillate, and thus they must have mass. That's a lovely result because it follows so immediately from basic physics, but also because the standard model of particle physics -- the bits of theory we think we understand well -- predicts that neutrinos are massless. That means that the standard model is wrong and there is new physics we don't understand, and physicists (conspiratards notwithstanding) love that.

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Microsoft commits: We're buying GitHub for $7.5 beeeeeeellion

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Re: Worst thing: M$FT has now full access to our PRIVATE REPOS!!

If you're keeping your source code *anywhere* on the internet in a form where it's not encrypted then at some point this is going to hapoen. The only defense is contracts with teeth and a supplier which operates in a jurisdiction where such contracts mean something (so, not the US, at least).

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Visa Europe fscks up Friday night with other GDPR: 'God Dammit, Payment Refused'

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Re: Cashless society

Or may be they, like all the other financial IT systems in the world, have a complicated system which has been carefully engineerd to be redundant but where people missed some obscure chain of events where there was not enough redundancy. If you've worked in financial IT you'll understand how common that is, and how hard it is to get right.

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Re: Useless, incompetent bastards

When was the last Visa outage again?

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MH370 search ends – probably – without finding missing 777

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Alien

The saddest thing

One of the most horrible things about this is that the people who may now never know exactly where in the sea their family and friends ended up will have to put up with another group of people for whom their real grief is far less important than pushing some stupid conspiracy -- 'it was flown to the MOON by elite climate scientists' or some such idiocy. And those conspiracies may now never end: the first inkling of one has already appeared in these comments.

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RIP to two 'naut legends: A moonwalker and a spacewalker

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Re: I disagree

This is silly. If the number of people-willing-to-go-to-space had gone down by a factor of a thousand since 1970 there would still be thousands of them.

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A Reg-reading techie, a high street bank, some iffy production code – and a financial crash

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total_exposure = sum(position.exposure for position in positions)

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Trump’s new ZTE tweet trumps old ZTE tweets that trumped his first ZTE tweet

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Re: "Everyone is allowed to make a mistake"

Exaxctly. This isn't a problem of smart vs stupid: it's a problem of good vs evil.

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