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May 18, 2009 | 22 Comments

Hey, Hollywood, I’ll do it for free

The Problem

This relevant scene appears in an uncountable number of movies. What happens when you plunge head first through a glass window? Anybody? That’s right. You die. It’s you that starts the jump, but it’s a shredded, bloody mass that finishes it. You will not stand up and brush shards of glass from your jacket. Instead, the mortician will politely aver to your widow that “Closed caskets are in this season.”

The accuracy of physics in movies is just barely above that portrayed in cartoons. While it’s funny to see Wile E. Coyote run past the cliff and only fall when he realizes there’s nothing but thin atmosphere between him and destiny, it boggles the mind to see essential plot points of movies and television shows revolve not just around unlikelihoods but impossibilities, especially when it’s so easy to correct the mistakes.

To prove it, I’ll first dissect the new Star Trek, then I’ll offer my solution to the dilemma.

Warning: Spoilers ahead!

The new Star Trek begins with a Romulan ship slowly poking through a black hold, time shifting itself into the past. Do you know what happens when anything passes into—but never through—a black hole? The gravitational potential is so intense that everything is stretched into a quark-thin spaghetti. There wouldn’t be enough left of the Romulans to even form a grease spot.

But let that pass.

This isn’t bad physics but screwy psychology: after the Romulans dust a Federation ship, nobody thinks to go looking for them. For twenty-three years. Well, people get busy. Let that pass, too.

The reason the Romulans had their adventure is that their sun had just gone supernova and wiped out their homeworld. Turns out Spock was on his way to that star to slip in some red matter (whatever that is) which would have turned the petulant sun into a black hole before it had the chance to explode—and thus he would have saved the planet (accepting the unlikely assumption the planet also couldn’t wander into the black hole’s gravity well) . He dithered, apparently, and only got there after the explosion.

Now, it is true that many stars end their lives by going super nova. But there are indications, subtle hints that can be gleaned that allow one to predict the cataclysm in advance—usually by at least a few million years. So it must be that Spock was substantially delayed. A woman, no doubt. Let that pass.

The advanced-time Spock also comes through the black hole and is easily captured by the Romulans. Later, the younger Spock pops in the cockpit of old Spock’s ship and trivially blasts his way free. Which only tells us that the advanced-time Spock was still distracted when he forgot his weapons. Sigh. I’ll let that pass.

Star Trek Monster!

Again not physics, but do you recall several months back when I said that every movie which features a monster has the beast not pounce and eat its human prey, but has it stop short, crane its neck, open its mouth, shake its head and roar. It’s the creature-feature version of monologuing, I guess.

Kirk was marooned with such a monologuing monster but was rescued when the elder Spock scared off the beast with a fire stick. Then Scottie transported himself and Kirk off their isolated rock using a new transporter formulation that allowed them to appear on a ship moving at warp speed half-way across the galaxy. All are amazed by this. Wow! That’s a long way!

Then everybody instantly forgets. Or else it would have occurred to them to use the same technology to transport a photon torpedo aboard the Romulan ship, thus saving everybody the hassle of tracking down the bad guys and face possible injury and property damage. But then we wouldn’t have got to see a score of panicked humans scurrying from a building in downtown San Francisco when the Romulans appeared out of nowhere! at the exact moment when every other ship in the galaxy were out of commission for tune ups.

Star Trek O2!

And we would have also missed the climatic scene where Kirk and young Spock bond while watching the Romulan ship disintegrate. It was imploding because a medicine-ball sized chuck of red matter had spilled out onto its floor. Earlier, it took just a drop of the crimson goo to destroy a single planet or star. But when a keg of it goes off, it does so slowly, which allowed time for Kirk to diss the bad guy. And it made him forget that a black hole would soon suck in his ship (a lot of failing memories in the future) and he barely got out in time.

Anyway, I still recommend the movie and rate it at $6 (via the Briggs Movie Rating System).

The Solution

A lot of bad physics in Star Trek. But it didn’t have to be that way. All of it was fixable because there were scores of us geeks who would have served as physics advisors for the movie—and most of us would have done it for free!

Thus, I hereby make the offer that I will, for no charge, give any Hollywood studio one hour of fact-based, solid physics critiquing. I don’t have to meet any actors, I don’t need to be introduced to the director, and I can do it all from my desk. You don’t even have to put my name in the credits. I will be satisfied to play a small part in the education of movie audiences.

You’ll (I’m speaking to you Hollywood) be gaining more than just better movies. You’ll keep annoying people like me quiet in theaters. We won’t have to stage-whisper to our seat-mates, “Let me tell you exactly why that can’t happen…”

May 13, 2009 | 11 Comments

Disparity is inevitable: a counter argument to filing discrimination lawsuits


Know a lawyer who is involved in a discrimination lawsuit? Particularly one in which the plaintiff alleges discrimination because actual disparities are found in company hiring practices? Were you aware that, just by chance, a company can be absolutely innocent of discrimination even though they actually are found to have under-hired a particular group? No? Then read on to find out how.

What are diversity and disparity?

We discussed earlier that there are (at least) two definitions of diversity: one meaning a display of dissimilar and widely varying behaviors, a philosophical position that is untenable and even ridiculous (but strangely widely desired). The second meaning is our topic today.

Diversity of the second type means parity in the following sense. Suppose men and women apply in equal numbers and have identical abilities to perform a certain job. Then suppose that a company institutes a hiring policy that results in 70% women and 30% men. It can be claimed that that company does not properly express diversity, or we might say a disparity in hiring exists. Diversity thus sometimes means obtaining parity.

Disparity is an extraordinarily popular academic topic, incidentally: scores of professors scour data to find disparities and bring them to light. Others—lawyers—notice them and, with EEOC regulations in hand that call such disparities illegal, sue.

And it’s natural, is it not, to get your dudgeon up when you see a statistic like “70% women and 30% men hired”? That has to be the result of discrimination!

Of course, it was in the past routinely true that some companies unfairly discriminated against individuals in matters that had nothing to do with their ability. Race and sex were certainly, and stupidly, among these unnecessarily examined characteristics. Again, it’s true that some companies still exhibit these irrational biases. For example, Hollywood apparently won’t hire anybody over the age of 35 to write screenplays, nor will they employ actors with IQs greater than average.

Sue ’em!

It’s lawsuits that interest us. How unusual is a statistic like “70% women and 30% men hired”? Should a man denied employment at that company sue claiming he was unfairly discriminated against? Would we expect that all companies that do not discriminate would have exactly 50% women and 50% men? This is a topic that starts out easy but gets complicated fast, so let’s take our time. We won’t be able to investigate this topic fully given that it would run to a monograph-length document. But we will be able to sketch an outline of how the problem can be attacked.

Parity depends on several things: the number of categories (men vs. women, black vs. white, black men vs. black women vs. white men vs. white women, etc.; the more subdivisions that are represented, the more categories we have to track), the proportion those categories exist in the applicant population (roughly 51% men, 49% women at job ages in the USA; we only care about the characteristics of those who apply to a job and not their rates in the population), the exact definition of parity, the number of employees the company has, and the number of companies hiring. That last one is the one everybody forgets and is the one that makes disparities inevitable. Let’s see why.

Men vs. Women

Throughout all examples we assume that companies hire blindly, that they have no idea of the category of its applicants, that all applicants and eventual hires are equally skilled; that is, that there is no discrimination in place whatsoever, but also that there is no quota system in place either. All hires are found randomly. Thus, any eventual ratio of observed categories in a company is the result of chance only, and not due to discrimination of any kind (except on ability). This is crucial to remember.

First suppose that there are in our population of applicants 51% men and 49% women.

Now suppose a company hires just one employee. What is the probability that that company will attain parity? Zero. There is (I hope this is obvious) no way the company can hire equal numbers of men and women, even with a quota system in place. Company size, then, strongly determines whether parity is possible.

To see this, suppose the company can hire two employees. What is the probability of parity? Well, what can happen: a man is hired first followed by another man, a man then a woman, a woman then a man, or a woman followed by another woman. The first and last cases represent disparity, so we need to calculate the probability of them occurring by chance. It’s just slightly over 50%.

(Incidentally, we do need to consider cases where men are discriminated against: in the past, we could just focus on cases where women were, but in the modern age of rampant tort lawyers, we have to consider all kinds of disparity lawsuits. For example, the New York Post of 12 May 2009, p. 21, writes of a a self-identified “white, African, American” student from Mozambique who is suing a New Jersey medical school for discrimination.)

Now, if a woman saw that there were two men hired, she might be inclined to sue the company for discrimination, but it’s unlikely. Why? Because most understand that with only two employees, the chance for seeming, or false discrimination is high; that is, disparity resulting by chance is pretty likely (in fact, 50%).

So let’s increase the size of our company to 1000 employees. Exact parity would give us 510 men and 490 women, right? But the probability of exact parity—given random hiring—is only 2.5%! And the larger the company the less it is likely exact parity can be reached.

Continue reading “Disparity is inevitable: a counter argument to filing discrimination lawsuits”

May 11, 2009 | 8 Comments


My western sojourn is complete. The thing that impressed me most about Livermore, and its neighbor Pleasanton, CA, is that both towns’ main streets have shops with life-sized fiberglass horses out front. Something you don’t find here in Manhattan.

I also rediscovered that I am a terrible and impatient driver. However, I managed not to kill or even seriously wound any human, and I caused almost no property damage, so my time behind the wheel must be judged a success.

Since I have been gone, the links have piled up. Here are a few of them.

Alarm Crock “Simon Briscoe, morbid Brit, statistician and co-author of the new book ‘Panicology,’ which uses hard data to separate actual threats from perceived ones.” Sent in by XYLKT.

Thiner is better to combat global warming This report, emailed from Ari, concludes the exact opposite of what Dr Harrister, PhD proved in a scientific study, and says fat people burn more CO2 than do thin people. But the report clearly fails to consider that thin people “exercise” too much and burn way more O2 (and thus convert that O2 into CO2).

London Book Review has reviewed Breaking the Law of Averages. Money quote: “If there’s a criticism of the book it’s that it really could have done with a better proof-read – sometimes the typos really do get in the way. Hopefully future editions will clear this up.” Amen, brother; I hope so, too.

The Tree Museum I get about three to four press releases a day, all inviting me to post. Most of them are asinine, and I’m not saying this one isn’t, but it is, at least, bizarre. Tree Museum is a novel which “is a social thriller that follows a world completely transformed by an enigmatic and powerful totalitarian force known only as the Signmakers. In effort to transform humanity into a self-sufficient and environmentally stable civilization, the Signmakers ruthlessly and systematically eliminate anything and any person that they deem wasteful. The story follows a torn couple on their odyssey throughout the American southwest while the Signmakers transform the world around them.” If anybody reads this, please send me a review. Might compete with this book for worst all time sci fi novel.

Why two? This was the question we asked of gay marriage supporters. It has been answered. “First came traditional marriage. Then, gay marriage. Now, there’s a movement combining both—simultaneously. Abby Ellin visits the next frontier of nuptials: the ‘triad.’..’I want to walk down the street hand in hand in hand in hand and live together openly and proclaim our relationship,’ says Sasha Lessin [1 of 3]. ‘But also to have all those survivor and visitation rights and tax breaks and everything like that.'” Sent in by Anonymous.

Peddlar joins PhD program without a degree! “Despite failing his college entrance exam years ago, the 38-year-old street peddler and part-time bicycle taxi driver from Jinzhou, Liaoning province, followed his love and continued to study classic Chinese literature on his own.” His work was eventually recognized by a university and he was allowed entrance. Gives you hope that there is still some sense left in the world. Sent in by my Number One Son.

Could deadly swine flu be caused by climate change? “Has climate change and poor water sanitation played a role in the emergence of a previously unknown deadly swine super virus? It is too soon to tell and a lot more investigation will need to be conducted…but it might be a very frightening and conceivable reality. ” (ellipsis and emphasis in original). It might also mean that we are dealing with a dull-witted columnist. Sent in by Bob Thompson.

May 7, 2009 | 8 Comments


Somebody told me that the place we call “California” was actually real and, as we have supposed upon surveying the news that emanates from there, not fictional.

So I decided to check for myself and go. I knew that I was actually in “California” when the radio announcer said, “Gov. Schwarzenegger today said…”

Now, I had heard of the governator before, but I never quite believed it. When I was confronted with the reality I broke out in giggles, startling my companions. They knew instantly the reason for my mirth and said simply, “We’re used to it.”

Yesterday, I gave a talk to the Engineering folks at Livermore Lab dressed in my typical gear (a suit, of course). I started, “Before I begin, I should explain my strange costume. Back where I come from, many people look like me.”

This eliminated the strange looks I had been getting, caused, no doubt, by the suspicion that I was some mysterious inspector.

I am now looking forward to the wine. Wente Vineyards tonight.

Anyway, I’m behind in answering the comments, which I promise do when I return early next week.