Category Archives: Mathematics

Interstellar

A light-on-spoilers review.

[Tuesday-morning update]

Uh-oh:

Christopher Nolan’s epic new sci-fi film Interstellar has received measured acclaim from critics, who have praised its ambitious scale and effects but were less convinced about the story.

That was the problem with Gravity, too.

[Bumped]

The New Consensus Study

on evolution:

Our search resulted in 487,629 papers that mentioned “evolution” or “natural selection” in the abstract. However 451,412 of those could not definitively be placed into one of our seven position-defining categories*, no matter how hard we tried with our group of 20 reviewers. [The consensus view among us is that these reviewers are completely independent and objective; their common participation at our web site devoted to presenting pro-selection arguments, but nothing to the contrary, is just not relevant in this case.**]

Of the remaining 36,217 papers, 35,167 (97.1%) supported the consensus position that over half of the observed evolution over the twentieth century is due to natural selection. The fact that only 126 of these 35,167 papers were actually focused on critically evaluating the topic at hand, i.e. the different possible mechanistic explanations of observed evolutionary change and/or speciation (e.g. random drift, founder and other stochastic events, mutation rate variation, instantaneous genetic barriers, etc), is an irrelevant point, a complete red herring. We can reasonably assume that in at least the majority of 50% of the time, none of these 35,167 authors would indicate agreement with a position that they themselves had not carefully investigated, without having more than half of a predominantly pretty good reason for so doing***. It’s just not really half as difficult as people make it out to be when you boil it down. As we have now done. For you.

In conclusion, there is very clearly a very strong consensus as to the influence of natural selection on evolution during the twentieth century and this consensus has been increasing as the evidence increases. It is important that policy makers realize this and take action. Please pick this up and disseminate it widely so everybody knows about it; everyone else is, so you will be part of the consensus effort if you do. Thank you.

Heh.

Peter Thiel And Global Warming

Why he’s skeptical:

“Whenever you can’t have a debate, I often think that’s evidence that there’s a problem,” Thiel said on The Glenn Beck Program. “When people use the word ‘science,’ it’s often a tell, like in poker, that you’re bluffing. It’s like we have ‘social science’ and we have ‘political science,’ [but] we don’t call it ‘physical science’ or ‘chemical science.’ We just call them physics and chemistry because we know they’re right.”

Thiel said no one will be upset if you ask questions about the periodic table, because it is actually science. But referring to man-made climate change as “science” tells you “that people are exaggerating and they’re bluffing a little bit,” Thiel said.

“The weather has not been getting warmer for the last 15 years. The hockey stick that Al Gore predicted in the early 2000s on the climate has not happened,” he remarked. “And I think as this monolithic culture breaks down, you can have more debates.”

Yes.

Judith Curry’s WSJ Op-Ed

She rounds up the (hysterical and unhinged) reactions:

Climate science has been thrown into disarray by the hiatus, disagreement between climate model and instrumental estimates of climate sensitivity, uncertainties in carbon uptake by plants, and diverging interpretations of ocean heating (in the face of a dearth of observations). ‘Certainty’ arguably peaked at the time of the AR4 (2007); perception of uncertainty is arguably greater than any time since the FAR (1991). Yes of course we know more about the climate system than we did in 1991, but more knowledge about the complex climate systems opens up new areas of ignorance and greater uncertainty.

In context of the way climate sensitivity is defined by the IPCC, uncertainty in climate sensitivity is decreasing as errors in previous observational estimates are identified and eliminated and model estimates seem to be converging more. Climate model simulations, when compared with 21st century observations seem to be running too hot, giving creedence to the lower observation-based sensitivity values.

What do the lower values of climate sensitivity imply for policy? Well slower values of warming make it easier to adapt, and provide time to develop new technologies and new policies. But the true believers such as Mann et al. call adaptation, developing new technologies and policies as ‘inaction.’ The policy logic apparent in the essays critical of my op-ed are rather naive.

So we are left with science in disarray and naive logic regarding policy. And the ‘warm team’ wonders why people are yawning?

She should cite my piece on the precautionary principle.

Is There An Open-Source Doctor In The House?

OK, so I installed Gnucash on my machine last week, and it worked like a charm. I rebooted over the weekend after a yum update (which included a kernel rebuild I think) and now when I try to load the program, it crashes, with this response:

Backtrace:
In ice-9/boot-9.scm:
157: 16 [catch #t # ...]
In unknown file:
?: 15 [apply-smob/1 #]
In ice-9/boot-9.scm:
3597: 14 [process-use-modules (((gnucash price-quotes)))]
702: 13 [map # ((#))]
3598: 12 [# (#)]
2864: 11 [resolve-interface (gnucash price-quotes) #:select ...]
2789: 10 [# # ...]
3065: 9 [try-module-autoload (gnucash price-quotes) #f]
2401: 8 [save-module-excursion # ]
3085: 7 [# ]
In unknown file:
?: 6 [primitive-load-path "gnucash/price-quotes" ...]
In gnucash/price-quotes.scm:
41: 5 [# ]
In ice-9/boot-9.scm:
3597: 4 [process-use-modules (((www main)))]
702: 3 [map # ((#))]
3598: 2 [# ((www main))]
2867: 1 [resolve-interface (www main) #:select ...]
In unknown file:
?: 0 [scm-error misc-error #f "~A ~S" ("no code for module" (www main)) #f]

ERROR: In procedure scm-error:
ERROR: no code for module (www main)

Any ideas from anyone what the problem might be? I’ve tried uninstalling/reinstalling, with no joy.

[Update a few minutes later]

Someone else seems to have the same problem, or a very similar one. I’ve emailed Mssr. Villemont.

Also, I’ve come up with a temporary fix to let me get taxes done. Skrooge seems to be able to import the data. It’s more of a personal finance app than for business, but it will let me do what I need to do until I get Gnucash fixed.

[Update a few minutes later]

Great. I can import my personal finances, but it fails when it tries to bring in the business books.

[Update a while later]

Good news. I deleted the file recommended at that page, and Gnucash seems to load properly now.

Global Warming

The statistical meltdown:

The sensitivity of the climate to increasing concentrations of carbon dioxide is a central question in the debate on the appropriate policy response to increasing carbon dioxide in the atmosphere. Climate sensitivity and estimates of its uncertainty are key inputs into the economic models that drive cost-benefit analyses and estimates of the social cost of carbon.

Continuing to rely on climate-model warming projections based on high, model-derived values of climate sensitivity skews the cost-benefit analyses and estimates of the social cost of carbon. This can bias policy decisions. The implications of the lower values of climate sensitivity in our paper, as well as similar other recent studies, is that human-caused warming near the end of the 21st century should be less than the 2-degrees-Celsius “danger” level for all but the IPCC’s most extreme emission scenario.

That’s the wrong answer. It doesn’t justify ending capitalism.

Orbits And Suborbits

I’ve updated yesterday’s piece at Ricochet to clarify, for those in comments. I’ve probably discussed this here before, but…

Per discussion in comments, there seems to be some confusion about the difference between high-altitude flight, suborbital flight, and orbital flight. As John Walker points out, orbital flight requires a minimum speed to sustain the orbit, but while that is necessary, it is not a sufficient condition. In fact, a flight can be suborbital with the same speed (energy) as an orbital flight. The best, or at least, most rigorous way to define a “suborbit” is an orbit that intersects the atmosphere and/or surface of the planet. So if you launched straight up at orbital velocity, it would still be a suborbit, because it would (after an hour or two, I haven’t done the math) fall back to the ground. So John’s numbers in terms of comparative energy are roughly correct for the particular vehicles being discussed here (XCOR Lynx and VG SpaceShipTwo), they can’t be generalized for any suborbital vehicle (e.g., a sounding rocket isn’t orbital, but it goes much higher than those passenger vehicles, often hundreds of kilometers in altitude).

The speed necessary to achieve orbit is partly a function of the mass of the body being orbited, but it is also a function of its diameter, and whether or not it has an atmosphere. If the earth were a point mass, an object tossed out at an altitude equivalent to the earth radius (that is ground level) would have very little velocity, but it would have a lot of potential energy. It would fall, gain speed, whip around the center and come back up to the person who had tossed it. That is, it would orbit. So even for the relatively low-energy suborbital vehicles discussed in this post, the reason that they’re not orbital is simply that the planet gets in the way.

One other interesting point is that, under the definition above, subsonic “parabolic” aircraft flights in the atmosphere, to offer half a minute or so of weightlessness (offered by the Zero G company), are suborbital flights, in terms of their trajectory. I put “parabolic” in quotes because in actuality, if properly flown, they are really elliptical sections, as all orbits and suborbits are. The parabola is just a close approximation if you assume a flat earth, which is a valid assumption for the short distances involved. Galileo did his original artillery tables based on flat earth, which is why beginning physics students model cannonball problems as parabolas, but modern long-range artillery has to account for the earth curvature, and it does calculate as elliptical trajectories.

Finally, one more extension. Ignoring the atmosphere, every artillery shell fired, every ball thrown or hit, every long jumper, every person who simply hops up into the air, is in a suborbit. The primary distinction for the vehicles discussed is that they are in a suborbit that reaches a specific altitude (at least a hundred kilometers to officially be in “space”), and leaves the atmosphere.

Clear as mud?

Dreamchaser And Stratolaunch

I didn’t mention this earlier in the week, but SNC is teaming with StratoLaunch to get a subscale version into orbit. If it’s 75% scale, I figure that’s about 40% of the current interior volume, which lines up with their claim of being able to carry two or three passengers (the full-scale system is designed for seven). The big advantage of such a system would be single-orbit rendezvous, and runway landing, so if it happens, there’d certainly be a market niche for it.

USB Devices

I hadn’t realized they’re more than just memory:

“People look at these things and see them as nothing more than storage devices,” says Caudill. “They don’t realize there’s a reprogrammable computer in their hands.”

In an earlier interview with WIRED ahead of his Black Hat talk, Berlin-based Nohl had said that he wouldn’t release the exploit code he’d developed because he considered the BadUSB vulnerability practically unpatchable. (He did, however, offer a proof-of-concept for Android devices.) To prevent USB devices’ firmware from being rewritten, their security architecture would need to be fundamentally redesigned, he argued, so that no code could be changed on the device without the unforgeable signature of the manufacturer. But he warned that even if that code-signing measure were put in place today, it could take 10 years or more to iron out the USB standard’s bugs and pull existing vulnerable devices out of circulation. “It’s unfixable for the most part,” Nohl said at the time. “But before even starting this arms race, USB sticks have to attempt security.”

Caudill says that by publishing their code, he and Wilson are hoping to start that security process. But even they hesitate to release every possible attack against USB devices. They’re working on another exploit that would invisibly inject malware into files as they are copied from a USB device to a computer. By hiding another USB-infecting function in that malware, Caudill says it would be possible to quickly spread the malicious code from any USB stick that’s connected to a PC and back to any new USB plugged into the infected computer. That two-way infection trick could potentially enable a USB-carried malware epidemic. Caudill considers that attack so dangerous that even he and Wilson are still debating whether to release it.

Great.

The Climate Science

…is not settled:

…the crucial, unsettled scientific question for policy is, “How will the climate change over the next century under both natural and human influences?” Answers to that question at the global and regional levels, as well as to equally complex questions of how ecosystems and human activities will be affected, should inform our choices about energy and infrastructure.

But—here’s the catch—those questions are the hardest ones to answer. They challenge, in a fundamental way, what science can tell us about future climates.

Yup. The 97% “nonsensus” is multiple strawmen, because all it ever meant, to the degree that it wasn’t just BS, was that scientists agree that there is a greenhouse effect and that therefore human-generated carbon emissions can affect climate. Beyond that, there is no consensus.

Computer Programming Are Hard

An email I just got from Amazon:

I hope this e-mail finds you well. Thank you very much for patiently waiting for my answer.

I’ve been checking regularly with our technical team on their progress with resolving the age range issue. It appears the issue is more complex than expected and we’re still working hard to get a solution for you.

I wanted to send you a quick e-mail to let you know the findings so far:

Since Amazon uses certain characters to classify books according to their content, it tends to be quite limited when it comes to character recognition. In the case of “Safe Is Not An Option,” although our platform gave you the chance to set the age ranges as 8 (min) and 18+ (max), the website is not displaying the (+) symbol because this character is generally used to determine when a book is of mature content or not. Since the book is targeted to people that are 8 and up, the system is finding a contradiction due the title being categorized as children’s, while being also set as an adult book because of the ’18+’.

We are aware indeed that what you wished to communicate is that the book was written for all people starting at age 8; even so, due to legal and international marketplace matters, the store has determined that the ‘+’ sign next to the ’18’ number makes reference exclusively to adult or erotica content, which results in a classification restriction. Due to this, the website removes the ‘+’ sign automatically and replaces it with the single ’18’ number to make your book fall within the appropriate ranges for children and adults.

We are still working to find a way to have the ‘8 – 18+’ displayed on your book’s page. Still, if by any chance the platform was unable to digest that entry, what I’d recommend to do is leave the age ranges as they are, and within the book’s description, you may clarify that the book is indeed intended for people aged 8 and up. I’ll let you know how everything goes!

I hope this information helps explain clearly the situation; I’m very sorry for how long this is taking, but I greatly appreciate your understanding!

I’ll be in touch again with an update as soon as possible.

Thanks again for your patience.

I’m kind of amazed that I’m the first person in Kindle history who wanted to show that a book could be enjoyed by children of all ages.

[Afternoon update]

I’ve at least updated the book description to say that it’s suitable for all ages.

Hockey Sticks And “Fraud”

Some reflections from Judith Curry on Professor Mann’s latest court filing.

[Update early afternoon]

Oopsie:

After being caught out claiming he was a “Nobel Prize recipient” in his original complaint (then having to retract it), it seems Mann and his lawyers just don’t have the good sense to know when to stop. In this case Mann has been “hoisted by his own petard”. His very own words condemn him. Again.

No comment.

The “97%” Nonsensus

As I noted on Twitter:

Judith Curry explains:

I think we need to declare the idea of a 97% consensus among climate scientists on the issue of climate change attribution to be dead. Verheggen’s 82-90% number is more defensible, but I’ve argued that this analysis needs to be refined.

Climate science needs to be evaluated by people outside the climate community, and this is one reason why I found Kahan’s analysis to be interesting of people who scored high on the science intelligence test. And why the perspectives of scientists and engineers from other fields are important.

As I’ve argued in my paper No consensus on consensus, a manufactured consensus serves no scientific purpose and can in fact torque the science in unfortunate ways.

And José Duarte is appropriately brutal:

Continue reading