# Here's a Scientific Concept More People Should Know: Gravity

Happy New Year!

Every year, Edge.org asks scientists a question. This year it's "What scientific term or concept ought to be more widely known?" Various worthies proposed things like neurodiversity, regression to the mean, Bayes' theorem, matter, and—

Wait. Matter? That's pretty widely known already, isn't it? Sure, but Hans Halvorson doesn't think most of us really get matter. Fair enough, and in that spirit I offer up my concept: gravity.

The truth is that I'm twisting the spirit of the question to gripe about one of my pet peeves. What I really want is a permanent ban on the infamous trampoline picture used to illustrate how Einstein's General Theory of Relativity explains gravity. Here's an example:

The idea here is that the trampoline illustrates the concept of warped spacetime, and it's adequate for that purpose. But if you place a stationary marble on the trampoline in the picture, what causes it to suddenly start rolling toward Earth? This only makes sense if there's some kind of secret gravity machine underneath the trampoline that pulls on the marble. This is not just oversimplified, as complex concepts often are in works for general audiences, it's flatly wrong. But even notable scientists continue to use this metaphor in books on relativity.

So how does relativity explain gravity? The weird thing about the trampoline metaphor is not just that it's wrong, but that the correct explanation is both easier to understand and way more interesting. Here's what you need to know: all objects in the universe are in motion. Even a seemingly stationary object is moving through time at a rate of one second per second. However, in the presence of a large mass (like the earth or the sun), spacetime is warped very slightly. For any object near a large mass, this warpage causes time to slow down, and this slowdown is converted into motion through space.

In a slightly more formal sense, we can say that neither intervals in space nor intervals in time are constant under all conditions, but the spacetime interval is. However, in order for that interval to stay constant, motion through space has to increase (i.e., objects speed up) whenever motion through time is reduced (i.e., time slows down).

The equation that describes this includes the term c2 (the speed of light squared), which is a huge number. In the famous equation e=mc2, it explains why a tiny amount of mass produces a huge amount of energy in an atomic explosion. In general relativity, it explains why a very tiny change in motion through time gets converted into a pretty large change in motion through space.

Now, in addition to being correct, isn't that more interesting? In the presence of mass, time slows down slightly, and this slowdown is converted into spatial motion toward the mass. That motion is gravity. And because spacetime is warped only slightly by mass, gravity is a very weak force compared to all the other forces we know about. Better than anything else, this gets across the idea that space and time aren't truly separate entities any more than length and breadth are separate entities. They are merely components of the broader concept of spacetime.

So here's what I think more people should know: how gravity actually works. And here's my New Year's resolution for other people: knock it off with the trampoline. You can find other ways of illustrating the warpage of spacetime, and it causes nothing but confusion when you (incorrectly) use it to explain gravity.

# The Lesson of 2016: Rabid Congressional Investigations Work

So what did we learn this year? That America is more susceptible to authoritarian populism than we thought? Not really. Trump's victory was a fluke, driven by Russian hacking, James Comey, and some bad polls in a few states.

That racism is on the rise? There's really no evidence of that.

That Democrats need to pay more attention to the white working class? Maybe, but no matter how many times people say otherwise, that really wasn't a root cause of Hillary Clinton's defeat.

I could go on, but instead I want to suggest something the 2016 election does teach us: persistent, obsessive investigations pay off. In the 90s, Republicans started investigating Whitewater. Even Ken Starr knew there was nothing to this after a couple of years, but he was put under pressure to keep at it, and eventually he hit some fluke paydirt: Monica Lewinsky. This had nothing to do with Whitewater, but who cares? Scandal is scandal, and it rubbed off enough on Al Gore that Republicans took back the presidency in 2000.

Fast forward to 2012. Hillary Clinton did nothing wrong related to Benghazi. That was clear pretty quickly, but Republicans kept at it. I laughed at them at the time, but they had the last laugh when they once again hit a fluke bit of paydirt: Clinton's private email server. Clinton didn't really do anything seriously wrong here either, but it didn't matter. Republicans kept at it for the next year and a half, and that was enough to convince a lot of people that Clinton was, somehow, corrupt and untrustworthy. That allowed Republicans to retake the presidency.

There was lots of other stuff going on too, but this is now twice that maniacal dedication to an investigation has paid off for Republicans. It's basically a way of hacking the media, which feels like it has no choice but to cover congressional investigations on a daily basis. It's news, after all, no matter how you define news.

So that's a lesson for sure. I'm just not sure what the solution is.

# The Future of Mass Transit Is Driverless

When we talk about driverless cars, we usually talk about driverless cars. But I was musing the other day about other driverless vehicles, and in particular how driverless technology will affect mass transit. I suspect it will make mass transit far more useful and more popular. I'm sure others have written about this in more detail, but here are my musings:

• Driverless buses. First of all, if we can build driverless cars, we can also build driverless buses and driverless light rail/subways.

• Cheaper buses. Especially in the case of buses, labor is a big part of the expense of operating a mass transit system. If buses become driverless, mass transit becomes cheaper, and that means metro authorities can afford to run buses more frequently. Frequency is one of the key features that determines how popular mass transit is, so this is a virtuous circle. The cheaper it is to operate buses, the more frequently they can run, and the more frequently they run, the more people will use them. Rinse and repeat.

• The last mile. Driverless cars solve the "last mile" problem. If I want to use a bus or train to commute to Los Angeles, I still need to get from the station to my workplace. If that's inconvenient—maybe my workplace is two miles away from the nearest bus stop, or maybe I'm just lazy—then I'll skip mass transit entirely. But it's easy to see how you could subscribe to a service that would track your progress and have a small driverless car waiting for you when you get off the bus. Hop in the car and it takes you the last mile. And since the car is driverless, it's cheap and efficient.

None of this means that cars will go away, of course. Commuting via car will also become more appealing if you get to sit back and relax the whole time. That said, if buses can be made a lot more convenient by a combination of more frequent operation and fleets of little cars for the last mile—and a lot cheaper than commuting as well—driverless technology could be the greatest boost for mass transit since the invention of the subway.

# Why Are CDs Cheaper Than Digital Downloads?

Last night I decided to buy a bunch of old-man albums from my youth that I've never gotten around to getting before. But old man though I might be, I am 21st century in my listening habits. I don't need a bunch of CDs cluttering up my house, just digital downloads. And yet, I ended up with a bunch of CDs winging their way to my house.

Why? Because out of a dozen purchases at Amazon, the audio CD was cheaper in all but one case. And about half the time, the audio CD included download rights. So I was buying a CD plus a digital download for less than the price of the CD alone.

Can anyone explain this? I know Amazon has some weird pricing policies sometimes, but this seems even weirder than usual. They could have saved themselves both warehouse picking/packing time and shipping costs if they'd priced the digital a buck less than the CD, rather than the other way around. Possible explanations:

• Most people consider digital files a convenience they're willing to pay for. It saves them the time of having to rip a CD.
• License rights something something something.
• I was a subject in a large-scale study to find out how irrational consumers are.
• Amazon is so used to losing money they just don't care.

Any other guesses?

# Friday Cat Blogging - 30 December 2016

It's Hilbert's turn this week, so he has the honor of hosting the final catblogging of the year. Here he is camping out on our neighbor's roof two doors down. He's about a hundred feet away from me, but in this era of cheap superzoom cameras that posed no problem. If you're wondering what it is that's caught his attention, the answer is Hopper. She was on the fence down below, and a few moments later jumped up to explore the roof too. There is no acrophobia among our cats.

# Sprint Update: 5,000 New Jobs, But They Still Don't Know What They're For

Last April, Sprint announced that it planned to hire 5,000 workers to deliver cell phones to customers at their homes. A few days ago it announced it would be hiring 5,000 new workers for...something. I surmised that these were actually the same 5,000 workers, and Sprint wasn't doing anything new. But apparently I was wrong. Max Ehrenfreund reports:

Representatives of Sprint have said the company will create positions for about 5,000 more people in the United States, counting both new employees and workers at Sprint's contractors.

....[Spokesman David Tovar] said that the new positions would be in addition to Sprint's previously announced plans to expand its presence on the street with 2,500 new stores and a fleet of vehicles for delivering phones. However, he added, the company has not yet determined exactly what the new workers will do or how many of them will work for Sprint as opposed to contractors.

Well...OK. But this is damn peculiar. We're going to hire 5,000 new people, but we don't really know what they're going to do. What kind of company does something like that? It's nuts. But they do know that a bunch of them will work for contractors. How do they know that? It's all very mysterious. But I guess Masayoshi Son wanted to suck up to Donald Trump, so he sent down word to hire 5,000 people and find something for them to do. Welcome to free enterprise, Trump style.

# Julian Assange Didn't Say WikiLeaks Gives Russia a Pass Because It's Already Open and Transparent

Readers who are extremely long in the tooth will remember a blogger named Steven Den Beste from back in the day. He was a gung-ho warblogger who wrote very long, very nerdy pieces about the urgent need to invade Iraq (with occasional forays into cell phone standards), so one day Daniel Davies decided that what we all needed was Shorter Steven Den Beste. Davies' version was usually a withering sentence or two.

Today, things have changed. I can think of all too many folks who could stand to cut their word count in half, but for now I'd settle for Shorter Glenn Greenwald. Yesterday he wrote this:

The Guardian’s Summary of Julian Assange’s Interview Went Viral and Was Completely False

According to Microsoft Word, the article clocks in at 2,645 words, so here's the nickel version. A few days ago Julian Assange gave an interview to Italian reporter Stefania Maurizi. (It is illustrated with the photo on the right, which I hope they don't mind me re-using since it makes me like Assange a little better than I usually do.) Here are the relevant sections:

Most of WikiLeaks' biggest revelations concern the US military-industrial complex....Why aren't human rights abuses producing the same effects in regimes like China or Russia, and what can be done to democratise information in those countries?

In Russia, there are many vibrant publications, online blogs, and Kremlin critics such as [Alexey] Navalny are part of that spectrum.....In Russia there are competitors to WikiLeaks, and no WikiLeaks staff speak Russian....WikiLeaks is a predominantly English-speaking organisation with a website predominantly in English. We have published more than 800,000 documents about or referencing Russia and president Putin, so we do have quite a bit of coverage, but the majority of our publications come from Western sources....The real determinant is how distant that culture is from English.

....What about Donald Trump?...What do you think he means?

Hillary Clinton's election would have been a consolidation of power in the existing ruling class of the United States. Donald Trump is not a DC insider, he is part of the wealthy ruling elite of the United States, and he is gathering around him a spectrum of other rich people and several idiosyncratic personalities. They do not by themselves form an existing structure, so it is a weak structure which is displacing and destabilising the pre-existing central power network within DC. It is a new patronage structure which will evolve rapidly, but at the moment its looseness means there are opportunities for change in the United States: change for the worse and change for the better.

The Guardian's piece, written by Ben Jacobs, made several claims: (1) Assange "long had a close relationship with the Putin regime," (2) Assange said there was no need for WikiLeaks to undertake a whistleblowing role in Russia "because of the open and competitive debate he claimed exists there," and (3) Assange gave "guarded praise" of Trump.

The first is unfounded, and the Guardian has now retracted it. The second is false as well. Whether you choose to believe him or not, what Assange said is that WikiLeaks isn't a local player in Russia and mostly appeals to English-speaking leakers. The third is hazier. Personally, I'd say Assange is wildly naive about Trump not representing an "existing power structure," and disingenuous in calling part of Trump's inner circle "idiosyncratic personalities." That said, "not a DC insider" plus "destabilising the pre-existing central power network within DC" plus "change for the worse and change for the better" could reasonably be described as "guarded praise." Those are all things that Assange pretty clearly views favorably.

This is a lot more than two sentences, but I'm not as witty as Dan Davies. In any case, I agree with Greenwald about two out of three of these things, and hopefully corrections will go as viral as the initial article. That's how things usually work in social media, right?

# Fox News and Food Stamp Fraud: The Finale

Abby Huntsman promised to "address" her baseless story about food stamp fraud on Fox & Friends today. So how did she do? Mediaite tells us:

Huntsman admitted the error the following day, reading a correction twice on-air: “We reported that back in 2016, \$70 million were wasted on food stamp fraud. That was actually incorrect.”

“The latest information from 2009 to 2011 shows the fraud at 1.3%, which is approximately \$853 million for each of those three years, and nationally food-stamp trafficking is on the decline. So sorry about that mistake,” she said.

"Food stamp trafficking is on the decline." I wonder how much of her audience understands that this means "food stamp fraud is on the decline"? Oh well. At least she mentioned it.

I have to say, though, that what I'm really curious about is where the original \$70 million figure came from. Made up out of thin air? Somebody read the wrong column in a report? Or what? I literally can't think of what sort of data you could dig up that would lead to this number, even in error. I suppose we'll never know.

# Even After Health Care, Per Capita Income Keeps on Rising

Here's another chart. I don't know why I did this one. I was looking at some other stuff, and then one thing led to another. But it seemed kind of interesting. Even after you account for ever-rising health care expenditures, personal income has been steadily rising for 60 years.

This does not show medians, so don't make too much of it. Especially over the past couple of decades, it's skewed by the massive income increases of the top 1 percent. A more interesting measure, I suppose, would be median disposable income after median out-of-pocket health care expenditures. Maybe I'll root around one of these days and see if I can find that.

# Chart of the Day: Food Is Cheap!

Whenever you point out that inflation is pretty low these days, you can expect a flurry of responses along the lines of, "Have you seen the price of eggs lately?!?" As it happens, yes, I have. More to the point, the US government tracks food inflation, and it's really low right now. As in negative. Food bought in stores (as opposed to restaurant food) is 2.2 percent cheaper than it was a year ago. This means the average family is spending about \$150 less on groceries than they did in 2015. Happy Holidays!