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Comment: Re:Yeah but ... (Score 1) 127

by radtea (#48214881) Attached to: Oldest Human Genome Reveals When Our Ancestors Mixed With Neanderthals

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.

Comment: Re: Exinction (Score 2) 127

by radtea (#48211011) Attached to: Oldest Human Genome Reveals When Our Ancestors Mixed With Neanderthals

Well, I don't think that quite matches the scientific concept of "species".

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.

Comment: Re:It may not be a *significant* factor ... (Score 2) 383

by radtea (#48200285) Attached to: Ebola Does Not Require an "Ebola Czar," Nor Calling Up the National Guard

While you are correct that the airborne vector isn't significant need I remind you that Ebola is not a disease whereby the person infected with it gets a mild fever and minor headache and the cure is two aspirin tablets?

Sure, but that has zero bearing on the degree of concern people should have about the epidemic potential of Ebola in any country with a first-world health care system (Nigeria, say, or parts of the US outside Texas.)

The thing fearmongers like the GP are all about is the attempt to create a sense that Ebola could actually be spreading like the flu, which is so trivially false it isn't even worth mentioning. Yes, PPEs that include good respiratory protection should be part of the standard patient-handling protocol, and all due care should be taken to avoid droplet transmission, but Ebola's almost complete lack of aerosol transmission is and will remain a substantial barrier to the population risk the disease poses: http://www.tjradcliffe.com/?p=...

Comment: Re:I'm still waiting... (Score 1) 161

by radtea (#48200207) Attached to: Cell Transplant Allows Paralyzed Man To Walk

You don't want your tax dollars to go towards stem cell research? Fine, that's a reasonable request.

No, it's not. Democracy--any form of government, really, but especially democracy--requires that citizens accept the democratic will within broad constraints. These constraints are usually called "rights" or similar. In Canada we have the "Charter of Rights and Freedoms", In the US you've got the Bill of Rights. In the UK you've got "a marshal nobility and a stubborn commons, possessed of arms, tenacious of property", at least in theory.

Within those constraints, though: anything goes. I don't get to withhold my tax dollars from enterprises I don't support. Neither does anyone else. Do my tax dollars go to things I don't approve of? You're damned right they do, and at times those things cause the death of other human beings, including adult human beings (our current federal government in Canada is spending some of my tax dollars to fight harm-reduction as an approach to drug use, for example, and people are dying because of that.)

So it is not a reasonable request to withhold anyone's tax dollars from any publicly funded enterprise so long as due process has been followed in the funding. Don't like it? Get involved in politics and change it.

Comment: Re:Why Cold Fusion (or something like it) Is Real (Score 5, Interesting) 349

by radtea (#48173983) Attached to: The Physics of Why Cold Fusion Isn't Real

Storms claims that there is no good theory to explain the excess heat measurements.

There is an excellent theory to explain the "excess heat" measurements: the people doing the research are some mixture of dishonest and incompetent. This theory also has the nice features that:

a) it is consistent with the spectacularly incompetent work we see whenever anyone attempts to carefully document an experiment, such as the one on the Rossi device we have seen recently

b) it is consistent with the litany of results that require well-established phenomenology to be turned off, for example the need to magically suppress neutrons and gamma rays that would otherwise be produced in any nuclear reaction or its aftermath, regardless of its origin.

After a quarter of a century with no reproducible results and no "positive" experiments that do not require the magical suppression of other laws of physics to account for the lack of radiation, no other theory is close to as plausible as this one.

Comment: Re:Why Cold Fusion (or something like it) Is Real (Score 5, Insightful) 349

by radtea (#48173915) Attached to: The Physics of Why Cold Fusion Isn't Real

Now I haven't seen anything convincing that indicates that cold fusion will work, but I also haven't heard of any significant investigation.

Cold fusion has been heavily investigated. There is one striking thing about all of the supposed "positive" results: they are physically impossible.

Suppose I said I had invented a car that ran on water, and that my claimed proof was that I had driven this car along the streets of a distant city. I give a talk on my results and show a map of the route.

A person in the audience interrupts and says, "Hey, I know that city! That's my home town! The route you've shown is impossible: you say you drove it between 4:30 and 5:30 PM on Tuesday June the 6th, which is in the middle of rush-hour, and you've shown yourself going the wrong way on half-a-dozen one-way streets! Why didn't you collide with anything?"

I reply: "This car runs on water! Weren't you listening? It doesn't collide with other cars, because it is propelled by water!"

You would be correct to suspect that you need not take my claims very seriously after that, and this kind of exchange is typical of cold fusion talks.

I saw Pons give a talk at Caltech, where one of my colleagues interrupted with the question, "Where are the neutrons? You say you don't see any radiation because all the energy comes out in high-energy alpha particles, but if you make alpha particles move with that energy through the palladium lattice you will get neutrons? Where are they?"

Pons answered: "New physics."

But alpha particles don't care what made them move, and more than a car cares what fuel it runs on. You can't just invoke "new physics" and say that the lack of neutrons or gamma rays doesn't matter, because you aren't really invoking new physics, you are throwing out old physics: you are saying that high energy alphas don't produce neutrons, even though that would require all of nuclear physics to be wrong.

So while I agree that new phenomena are often difficult to reproduce and we should be cautious about dismissing them on that basis, cold fusion, after twenty-five years of testing, has proven to be:

a) impossible to reproduce (there is no reliably reproducible experimental setup)

and

b) what experiments that have claimed positive results have always (to the best of my knowledge) required almost all of nuclear physics to be wrong to explain the absence of radiation.

I cannot think of any other phenomenon that eventually proved to exist that shares anything like this history of failure. Maybe Lister's work on sterile technique in surgery, which had a decade or two of rough handling? But even it was frequently reproducible, even if not universally so, and it didn't contradict any well-established, empirically founded, reasonably comprehensive theories of the time.

Comment: Re:Ebola vs HIV (Score 1) 381

by radtea (#48161879) Attached to: How Nigeria Stopped Ebola

No, it really doesn't. It's too hard to transmit, and almost certainly will remain so.

Saying it has "the potential" to wipe out half of humanity is mindless fear-mongering. The US has more guns that people, and therefore it is true to say that guns in the US have "the potential" to kill everyone, but I don't see anyone panicking about it, just arguing whether 30,000 deaths per year is an acceptable loss. To use "potential" in the sense you are is almost completely meaningless.

Comment: Re:SEALs possibly found WMD evidence early in the (Score 2, Interesting) 376

by radtea (#48154031) Attached to: Pentagon Reportedly Hushed Up Chemical Weapons Finds In Iraq

As to why, I can only guess.

You (or the SEAL books you refer to) make several contentions:

1) Iraq was actively engaged in new WMD production prior to the American invasion

2) The "diplomatic process" was intended (by whom?) to give Hussein time to hide this

3) The evidence as dismantled and relocated, likely to Syria

4) And the one we all agree on: the old stockpiles were found in Iraq

I've heard these claims before, particularly the one about Syria. The problem for anyone who takes this line of attack is explaining why the Bush Administration didn't put any of this together to make a case for the invasion and occupation after it was all discovered?

So what's your guess as to why the Bush Administration kept all this quiet?

Were they completely incompetent and let the military cover things up? If that's the case, why did the military cover things up?

Did Administration officials know all this--including the stockpiles etc being moved to Syria--and cover it up for their own reasons? If so, what were they? "A momentary lapse of reason" won't cover it. What is the plausible strategic, tactical, diplomatic or political reason for an Administration that made the invasion of Iraq a signature policy based on a pretext that was widely believed to be false to cover up evidence that would have proven that pretext substantially true?

This is the question that has to be answered.

Finally: if all the WMDs were moved to Syria, why are these WMDs still all over Iraq? (they were presumably in a lot better shape in 2002 than they are today, twelve years later.)

Comment: Re:wow (Score 5, Insightful) 566

by radtea (#48152587) Attached to: Lockheed Claims Breakthrough On Fusion Energy Project

Third, fission leaves behind nuclear waste materials with a half-life in tens of thousands of years--this is nasty stuff and is around basically forever. Fusion produces no long-lived waste (there is probably some component of some alloy that will prove to make tiny amounts of bad waste, but nothing significant compared to fuel rods from fission reactors).

The critical thing to understanding this is that fission reactors are (necessarily) full of heavy elements, which is where the long-lived stuff comes from. Fusion reactors are full of light elements.

There are very fundamental physical reasons why radioactive light elements almost always have much shorter lifetimes than radioactive heavy elements. If you've only got a few nucleons to play with, turning a proton into a neutron is a major change in configuration, so the energy gap between the radioactive isotope and the adjacent stable isotope is large, and in general the lifetime against beta decay scales inversely with the fifth power of the endpoint energy. In heavy elements, which have so many nucleons they can be adequately modelled as liquid drops in some cases, changing one neutron to a proton doesn't change the configuration very much so the energy difference is small and the lifetime can be very large. Unfortunately, although the energy of the beta particle emitted is small, the energies of the other particles in the decay chain (gammas and more betas in most cases) can be pretty much anything.

So: heavy elements (fission) bad; light elements (fusion) good. Fusion reactors are designed with this in mind. They will produce a lot of nasty stuff, but almost all of it will decay rapidly, so given that the engineering issues of fission waste are pretty much under control (the political issues are not) we can be confident that fusion power will be OK in that regard.

Comment: Re:Charging amperage (Score 1) 395

It doesn't say what the capacity of this battery is.

It also doesn't say what the energy density is, and there is a comment that something called the "power density" needs improvement.

Searching around a bit, it looks like this is a bit of incremental improvement on Lithium Titanate to facilitate faster charging. The theoretical energy density is 175 mAhr/g at 1.5V or about 1 MJ/kg (petrol is ~40 MG/kg): http://www.the-cryosphere.net/...

This is at the top end of current Li-Ion batteries, so faster charging makes sense. I see also that there are "power densities" in W/kg reported for some battery types, so I guess that's a term of art in the battery business (it has been my experience that applied physicists routinely blind themselves to what they are doing by adopting such terminology, as it typically pertains quite restrictively to the state-of-the-art at the time the terminology was thunk up.)

Comment: Re:Hoax (Score 4, Insightful) 986

Their measurements indicate more power is output than was input.

These measurements indicate the researchers have created an almost cartoonishly bad "open calorimeter" that they do not calibrate at anywhere near the operating temperature despite their estimate of heat balance being acutely dependent on making multiple temperature-dependent corrections accurately.

If a fourth year engineering student handed this experimental setup in as a design project, and included the low-temperature "calibration" as part of the design, I would fail them.

Comment: Re:Hoax (Score 2) 986

If they are making consistent measurements, however, it could be very tricky to fake data which shows consistent rates of consumption for nickel-58 and nickel-60 given the starting abundance.

They were not making continuous measurements. They were not allowed to look inside the device. Rossi was present during the "fueling" of the device.

So: ideal conditions for fraud. I wonder why that is?

If it was me doing it, I'd pre-load the device with isotopically enriched nickle when I constructed it. This would be mixed with and come out with the added "fuel". There are various ways of ensuring the mass balance is right (making sure some of the added "fuel" stays in the device) so the device would weigh the same before and after, but the extracted "fuel" would have an excess of 62Ni.

Comment: Re:Any suffiently advanced tech... (Score 1) 986

You absolutely need to know what's in the black box before validating any claims of the owner.

In this case, the claimed energy density is far outside the realm of anything achievable by chemistry, so if it was real it would be prima-facie evidence of something non-chemical going on.

That said, this this work is so obviously of poor quality--to the extent that I wonder if it was designed that way--I don't think it matters if anyone can look inside the box.

If the designed a closed calorimeter that they put the entire apparatus into, including an inverter, ran DC power into it, and measured the subsequent temperature rise, I could be convinced that something interesting was going on even without knowing what was inside.

Although I do agree that the claims being made are so extraordinary that even then it would be difficult to credit it as a real phenomenon.

This is a good time to punt work.

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