IRA FLATOW: This is Science Friday. I’m Ira Flatow. A bit later in the hour we’re going to talk two video game designers who are pushing the boundaries of what you can feel, what you feel playing a video game. Amy and Ryan Green we’ll talk about their game, That Dragon, Cancer.

But first, what’s the one universal expression that cuts across cultures? Turns out it’s the I don’t think so face. You know, imagine your boss asking you to stay late tonight, and you say, I don’t think so. It’s that one. And Rachel Feltman puts the face on the story and other selected short subjects in science. She’s editor of the Speaking of Science blog for the Washington Post. I don’t think so Rachel.

[LAUGHING]

RACHEL FELTMAN: Yeah, so scientists are calling it the not face. And it’s a combination of the fee expressions you see for anger disgust and contempt. And the reason they were interested in the not face is that they thought that it might actually be a kind of grammatical marker.

Now when we talk about human language and how it’s different from other communication and other animals, a lot of time scientists come back to grammar. There’s some research that shows that birds might use grammar, but it’s really nowhere else in the animal kingdom. And so we’re always looking for the origins of that.

And scientists thought that this facial expression, which kind of is your response to directly negating whatever was just said, might be more than just emotional expression. It might actually be used to kind of punctuate your sentence. And when they looked at different speakers making this face while they answered a question that apalled them, they found that it was universal and, more importantly, they found that people using American Sign Language sometimes dropped the sign for not and used the facial expression as the only indicator that the sentence was negative.

IRA FLATOW: So there is an expression?

RACHEL FELTMAN: Right.

IRA FLATOW: For that face in sign language.

RACHEL FELTMAN: Well, just instead of signing that they thought that was a bad idea, they would be signing their thoughts and instead of using the not, they were using be not face.

IRA FLATOW: Aha.

RACHEL FELTMAN: So, they think that that’s a pretty good indication that this connection they thought was there is there, and they’re actually going to go through YouTube videos and do big data analysis to try to find more faces that are woven into language this way.

IRA FLATOW: Is there a universal yes face?

RACHEL FELTMAN: Well, if there is, it’s not as easy to spot as the not face, but they’re hoping they’ll find it.

|LAUGHING]

IRA FLATOW: That’s interesting that so much information can be conveyed and then that it is so universal.

RACHEL FELTMAN: Right.

IRA FLATOW: Around the world. Let’s move onto l last month. We were watching an asteroid that could have come close to the earth, but a space rock did slam into Jupiter two weeks ago.

RACHEL FELTMAN: Yeah. So the cool thing about this story is that we wouldn’t know about it if it wasn’t for a couple of amateur astronomers. A video from Austria was brought the attention of Phil Plait, over at Slate, and it was just someone in their backyard with a telescope watching Jupiter and seeing this flash that looks like it might be an impact.

But it’s hard to look at one video and say what it is, no matter what, so he put out a call for other videos and it turned out an amateur astronomer near Dublin had picked up the same thing. So based on what they recorded, it seems pretty likely that a comet or asteroid hurled into Jupiter. And it was probably actually really small based on flashes that have been observed previously. It was probably only about 30 feet across.

But because Jupiter’s gravity is so powerful, the velocity of anything hitting it is huge and the impact energy would have been 25 times what it would have been for the same object to hit Earth.

IRA FLATOW: It’s like over 100,000 miles an hour.

RACHEL FELTMAN: Right. Just like incredible gravity, incredible velocity, so that’s how you get a relatively small rock creating a flash that somebody could see with their telescope here.

IRA FLATOW: You know, when I read this story, it reminded me of a story we did back in 1994, when the comet Shoemaker Levy 9, was going to slam into Jupiter also. That was going to be a big event and, actually, is another amateur astronomer, Levy, we had David Levy come on the show and anticipate for us what was going to happen.

DAVID LEVY: It’s not the size of the special effects that really matters here. It is to look at for all of the surprises, all of the unknowns. This is going to be the largest campaign for a single event in the history of astronomy.

IRA FLATOW: And it left a pretty big scar.

RACHEL FELTMAN: It did. Yeah, the comet broke up into, I want to say, 22 pieces, but a lot of those pieces left scars. They changed Saturn’s ring a little bit. They’re atmospheric effects that they can still see today.

IRA FLATOW: It’s very interesting. A few months ago, we talked about a theoretical alien mega structure that could be surrounding a distance star, aliens. You know, the odds were it could just as easily be an alien as anything else. And now scientists have come up with a hypothetical alien laser protection system?

RACHEL FELTMAN: Yes. So most of the time when we do these weird thought experiments about aliens, it’s about how to find aliens. But this one says, what if we want to hide from aliens? Which is a big, ongoing debate that we won’t get into.

[LAUGHING]

IRA FLATOW: But, come on.

RACHEL FELTMAN: The idea is that our detection of planets that could host life all relies on transiting planets. They pass in front of their star, from our perspective, and they change the stars light. They make the star flicker, dim, and we use that to learn about the planet.

So the idea is, if other planets are looking at us that way, how could we hide the fact that our planet was passing in front of the sun and we could do it with a laser. This study calculated how much power it would take and they came up with, I think, that 30 megawatts a year for 10 hours. Just that one burst to hide the transit.

It would take significantly more power to hide every wavelength of light that the sun puts out. That would just have visible light, but you could use a little less and just kind of mask the presence of life on Earth. You could make it look like Earth was just kind of an atmospheric-less dead rock.

IRA FLATOW: So an atmospheric dead suddenly got a laser beam.

[LAUGHING]

RACHEL FELTMAN: Yeah. So the problem here is that it’s assuming that this intelligent life wouldn’t have a better, or at least very different way, of looking at our planet. It’s possible to this laser would have nothing to do with how they were detecting us.

We could also use the same principle to make our signal even louder. While we were transiting, we could make these weird flashes, ala alien mega structure and try to get their attention. But it also raises the possibility that aliens might be hiding from us using lasers because of how terrible we are. So I found that a little depressing.

IRA FLATOW: I find, well, anything’s possible, if they’re hiding from us. Anyhow, thank you Rachel.

RACHEL FELTMAN: Thank you.

IRA FLATOW: A fascinating story. There’s always Rachel Feltman editor of the Speaking of Science blog for the Washington Post. And now it’s time to play good thing, bad thing.

[MUSIC PLAYING]

IRA FLATOW: Because every story has a flip side. Well, if you’re in traffic right now, imagine going for a drive and never having to stop for a light. Never having to wait for that guy making a left turn. You know who I’m talking about. Never needing to come to a complete stop at the intersection.

It’s a possible future in a world of autonomous vehicles all signed into a system that would coordinate their movements at intersections. Think of air traffic control like they do for planes, control where they are. They would do that for merging vehicles. Joining me now to talk about the good and bad of autonomous intersections is Evan Ackerman, contributing editor at IEEE Spectrum. Welcome back.

EVAN ACKERMAN: Hey, good to see you Ira.

IRA FLATOW: So how would these work? Is it very much like air traffic control, but for cars?

EVAN ACKERMAN: Yeah. It’s almost exactly the same. So the idea here is that, if you have autonomous cars they all communicate with intelligent intersections, then it would make intersections work a lot like an airport.

So your car will talk to the intersection over the internet and say something like, hey intersection, I’m approaching from this direction and I’m going this fast and I’d like to pass straight through you in 10 seconds.

And then it’ll be the intersections job to coordinate with all of the other cars that are talking to it to make sure that right when your car shows up, they’ll be a gap in the traffic just large enough for you to squeeze through safely.

IRA FLATOW: Hm. So what’s the good thing about this?

EVAN ACKERMAN: Well the good thing is that, hypothetically, we’ll be able to get rid of stop signs, and get rid of traffic lights, and just get rid of all of that annoying waiting around that we have to do at intersections right now. All of it could just go out the window. Intersections would just be something that you pass straight through.

And MIT has these really cool simulation videos of this happening. And, honestly, they’re kind of scary to watch because you’ve got this intersection where cars are passing through from four different directions, and cars are turning across lanes, narrow weaving in and out, and barely even slowing down and, somehow, none of them hit each other and it’s probably going to be terrifying for us to go through this, but you’ll never have to stop and that’s going to be great.

IRA FLATOW: So what could be bad about this?

EVAN ACKERMAN: Well, the first thing is that it doesn’t really work unless all of the cars going through the intersection are autonomous. And so, that’s got to happen first. Because a car driven by a human is going to be, by far, the most dangerous thing on the road in a world of autonomous cars and if you have a human-driven car trying to go through this intersection. It would just mess it up completely.

And the other obvious problem is that this doesn’t really take into account all of the other ways that intersections are used. So you’ve got pedestrians trying to cross the street, you’ve got people on bikes, stuff like that. And, at the moment, autonomous intersections don’t really know how to deal with that sort of thing, even in simulation.

IRA FLATOW: So what’s the advantage over this over individual cars talking to each other without a central system?

EVAN ACKERMAN: It’s much more efficient to have the intersection controlling everything. It’s also more reliable because the intersection has this big overview of everything that’s happening. And when you have the intersection in control, you can actually get cars to cooperate with each other more effectively. You form them into these little platoons and they go through the intersection in groups and that’s a lot more efficient than just one at a time.

IRA FLATOW: Now what if you created this right as you start your trip from home and you program where you want to go? Would it control all the other cars that are on the road too? And would people put up with that? They maybe have to go a little longer.

EVAN ACKERMAN: Well, if the researchers did some simulations of exactly how much you’d have to adjust your speed in order to get all this to work, and it’s really not that much. You maybe slow down slightly when you approach intersections to give other people time to get through, but it’s so much better than having to stop completely that you’re going to save maybe a minute or two per intersection, and the worse traffic gets, the more time you’ll save.

IRA FLATOW: You know, some of those folks with road rage, 10 seconds is too long. And you haven’t– Evan Ackerman as a contributing editor at the IEEE Spectrum.

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