I'm not sure why this was modded "Insightful" but it suggests that others share your questionable views, so I'll reply to them.

1) Scientists are not certain that dark matter is exotic particles, which is why scientists write papers like the one under discussion here. What seems misguided to me is people who are apparently ignorant of how science--which is the discipline of publicly testing ideas by systematic observation, controlled experiment, and/or Bayesian inference--works commenting negatively on how science works. It's a bit like Creationists critiquing their own bizarre views of "evolution" while ignoring the actual theory of evolution.

There has never been a time in the past several decades when any actual scientist has been even remotely certain about the nature of dark matter. Various ideas have been put forward, including ideas that modify gravity, and none of them have stood up to the routine tests applied to them. This has driven research toward exotic particles.

In particular: Big Bang Nucleosynthesis puts very tight constraints on the density of baryonic matter in the universe, and it's only about 5% of the amount needed to explain the large-scale cosmological observations that imply dark matter. So it isn't like scientists are just saying, "Yay! Evidence of new particles!" Rather we are saying, "Damn, there's a problem we can't solve with baryonic matter."

2) Occam's razor is stupid. You know, of course, that Occam himself used it to "prove" that nothing existed other than God, since to invoke other entities (matter, the Earth, shoes, cats...) to "explain" the phenomenology of experience would be to "multiply entities above necessity".

In the cases when it works or makes sense, Occam's razor is "Bayes' Rule for Dummies". The prior plausibility of a horse being around is higher than the prior plausibility of a zebra being around. Since both horses and zebras create hoofbeats with equal probability, hearing hoofbeats increases the plausibility of the propositions "There is a horse around" and "There is zebra around" by the same factor. Since horses were more plausible before, they are more plausible after.

That is:

p(zebra|hoofbeats) = P(hoofbeats|zebra)*p(zebra)/P(hoofbeats)

p(horse|hoofbeats) = P(hoofbeats|horse)*p(horse)/P(hoofbeats)

Since P(hoofbeats|zebra) ~ P(hoofbeats|horse) and p(zebra) < p(horse) and P(hoofbeats) = P(hoofbeats), it is trivially true that p(zebra|hoofbeats) < p(horse|hoofbeats).

No notions of "simplicity" are required.

So: your comment is quite badly mistaken.

The interesting bit of the paper is pointing out that observational limits excluding Standard Model-ish dark matter are incomplete. This is significant, as the new physics required to make stable "macros" of the kind discussed (nuclear-dense objects in the range of a few hundred grams to around the mass of the Earth, with a gap in the middle) is quite a bit less substantial than that required for physics beyond the Standard Model.

It it not-inconceivable that the strong force could have some weird metastable minimum for objects on this scale, and not being able to rule out such objects by observation is a problem, so we really should spend a bit of time closing those gaps.

One of the definitions I found was:

One who makes great sacrifices or suffers much in order to further a belief, cause, or principle.

I am sure that fits. While SpaceShip II is mainly intended for a non-exploration purpose, the program has resulted in some significant advances in rocketry and White Knight II has significant non-tourism use. These pilots have been involved in other space efforts, I remember the one who was injured from the Rotary Rocket test flights. There are lots of safer ways for these folks to make as much money as a test pilot is paid. They do what they do to advance our progress in aeronautics and space.

Martyrs? Who killed them for their beliefs?

Go away, troll. They certainly died while pursuing something intensely important that they were willing to risk their lives for. The fact that you weren't around to pull the trigger makes them no less martyrs.

I guess I shouldn't be surprised by all the non-sequitur hate this comment is getting from anonymous cowards. I don't generally reply to comments, but the ones here are so hateful and stupid it seems worth putting a word in.

No one asked anyone to do gay porn, for the illiterate amongst you. No one was asked to make out with anyone. You're going to have to address what I wrote rather than your fevered imaginations to get any traction, I'm afraid.

We frequently do films that cast actors as psychopaths, murderers, clowns, and worse, and no one ever objects, so any suggestion that playing a gay person is exceptionally offensive against the morals of the actor requires that it be more morally repugnant for them to play a gay person than a murderer. That is... odd.

Seriously, in one film there were half a dozen murders on screen. No one objected. Yet someone objected when given the option to play a gay person. If you don't see a problem with that, you're kind of screwed up.

Absolutely. The difficulty is that "action" has to get past a fence of anti-science, anti-technology, anti-capitalist nutjobs who say on the one hand that a) we face a civilization-ending event and b) we must not use various well-known and ready-to-go solutions to the problem, but instead must embark on an unproven revolutionary program that "changes everything!"

Nuclear power, carbon taxes, and research in to carbon sequestration are the obvious immediate responses to climate change.

The first two are practical, proven and ready-to-go. The latter is a backup plan.

Instead we have left-wing idiots protesting oil pipelines, because that's where the donation dollars come from.

With regard to carbon taxes: we have to tax something to fund government. Even righties who just want to use government money to bomb brown people generally agree with that. We can tax income, or we can tax carbon emissions. Who but a raving anti-wealth socialist would want to tax something good and wonderful like income when we can tax some basically nasty like carbon emissions instead?

I work in tech in a very liberal Canadian city and have a bunch of gay friends, and sometimes get lulled into thinking the world is a big happy accepting place.

Then I step outside the downtown bubble, just by a few miles, and I'm stunned by what I sometimes encounter. I do a little writing for a group that makes short films, and we had a shoot where one of the actors didn't show up. He was part of a couple, and I suggested we recast the part using a woman who didn't have a part yet, so the couple would be gay but everything else would be the same. The film was about relationships and this couple was fighting about stuff. There might be a hug at the end, but nothing more overtly affectionate than that.

The young, professional woman I suggested this too looked at me with her eyes literally wide with horror and said, "I'm sorry, I can't do that. I'm really straight."

In that situation it wasn't my place to berate her for her bigotry, particularly as I didn't think until much later of the correct come-back: "You're really earthbound, too, but I bet you'd play an astronaut if I asked you to."

So yeah, while to so many of us this is a done deal, our gay friends and family still have to walk around every day wondering when they are going to encounter that kind of horrified rejection, and while at least they don't get beat up as often as they used to it still has to be pretty awful for them.

If anyone wants people like Tim Cook to stop making a big deal about being gay (and really, don't we all want that?) they should make sure to be accepting and matter-of-fact about the gay people all around us, whose much-talked-about "agenda" involves living happy, fulfilling lives.

A generation of rabid opposition to nuclear power is wrong, as is using climate change as a stick to beat global capitalism with rather than saying, "Hey, all we need is a carbon tax and we'll be done" (this is what the evidence in the Canadian province of British Columbia shows, anyway, but who cares about evidence when you're busy fighting global capitalism?)

I don't see that this experiment is any different from a photon reflecting between parallel partially-silvered mirrors. You see a range of arrival times at the detector, despite the wavefunction being "fragmented" by multiple reflections.

So this won't do anything to advance measurement theory. It is an interesting example because of the exotic circumstances. Your description is extremely good and quite plausible, although I haven't read the paper either.

This is interesting, as there has been a huge fight in Canada about whether heavy oil sinks or floats (the answer seems to be: sinks, at least after some processing by sun/wind/flotsam/etc) but it has been presented to the public as if there was something special about that.

Whereas these results seem to indicate that a very substantial fraction of ordinary light crude sinks, so there is no particular additional danger posed by bitumen.

Or, alternatively, men are being sold a bill of goods, as they always have been, about their prospects in a particular profession (soldiering comes to mind) and the poor weak-minded little dears that they are, they are buying into it, resulting in huge amounts of effort going to waste as boom turns to bust and men bear the personal cost of society selling them nonsense.

But of course, no one, anywhere, ever cares about men. After all, men have full and complete autonomy and are never in any way influenced by societal pressures or the social construction of masculinity. Men die earlier, commit suicide vastly more often, are the primary victims of violent crime, are killed on the job far more frequently... and it's all because of the bad choices they, as perfectly autonomous individuals make. What other reason could there possibly be?

This is a general problem with the way people infer origin dates from sparsely sampled distributions: http://www.tjradcliffe.com/?p=...

The earliest anatomically modern human fossils date from about 195,000 years ago, and people often say on this basis that anatomically modern humans appeared about 200,000 years ago, which is statistically illiterate at best.

Maybe people in the field know better, but I've seen an awful lot of claims like this and even in the semi-professional literature there seems to be a strong tendency to assume origin dates based on "date of earliest discovery plus a bit", which is just the wrong way to do it.

There is no generally-agreed-upon "scientific concept of species". The "Biological Species Concept" is a well-know and highly contentious artifact. It is clearly useful, but how it is defined varies enormously from person to person and across sub-fields.

This variation doesn't matter much in practice, but it gives philosophers who for some unfathomable reason want there to be just one BSC fits. They seem unaware that concepts are tools used by knowing subjects to understand objective reality, so different subjects with different purposes will tweak the tool as appropriate, much the way a carpenter and a plumber are apt to use different types of hammer.

Anyway, I have better uses of my time than to waste another minute with you.