IRA FLATOW: This is Science Friday. I’m Ira Flatow. It’s been said many times by many experts, the quantum world is just plain weird. The idea that you could have two subatomic particles somehow entangled with each other, having some mysterious connection to each other, sounds like science fiction. But last Monday, China launched a satellite into space to test a possible practical application of that quantum weirdness, a so-called quantum satellite. As stated by China’s state run news agency, it’s two year mission is designed to establish hack proof quantum communications I’m transmitting uncrackable keys from space to the ground, and provide insights into the strangest phenomenon in quantum physics– quantum entanglement.

Here to tell us about that and other selected short subjects in sciences, Amy Nordrum. She’s an associate editor at The IEEE Spectrum here in New York. Welcome back, Amy.

AMY NORDRUM: Hi, Ira. Thanks.

IRA FLATOW: Quantum satellite communications. What does that even mean?

AMY NORDRUM: So this is a novel concept. This is the first satellite of its type to be launched. And the idea here is when we’re talking about quantum, we’re talking about a single particle. So in this case, it’s a photon, a single photon, which is a particle of light. So the idea here with this satellite is on board the satellite, there’s a laser and a crystal. And they can use this to split a photon in half. So you have a pair of photons. And those photons, you can then measure the properties of them relative to each other. And by doing this, you can use those properties and your knowledge of that in order to transmit is secure encryption key down to a ground station that could then be used to decrypt a message.

So this is supposedly a hack proof form of communications, which I think we would all really love to have.

IRA FLATOW: So if that’s one photon at a time, it’s going to be kind of slow, this communication.

AMY NORDRUM: Yes, this is not the sort of communication that we would be using to transmit the things that we transmit on the internet right now. This would be a way that we transmit a key that would keep certain messages highly secure. So we would perhaps first see it rolled out for military applications, for very highly secure government applications, perhaps for banks or financial firms. That’s the sort of places that we could probably expect to see it used first.

IRA FLATOW: So the magic here is that because you start with one photon and split them in two, these two are then entangled. And whatever happens to one simultaneously happens to the other on the ground.

AMY NORDRUM: Or in this case, there’s a nice way that you can basically use one as a reference to the other. So when you transmit a photon down to Earth from the satellite, you could keep that one on the satellite as a reference material. So if you receive the one on earth, you know its properties relative to the one back on the satellite. And if anybody has tampered with that photon on the way, it might have altered those properties in such a way that you’d be able to tell. It would be very obvious that it had been tampered with. And then you could know that that message was not one that you wanted to believe or trust.

IRA FLATOW: So that supposedly is the crack proof method.

AMY NORDRUM: Exactly, correct.

IRA FLATOW: So I’m sure there’s other people will be trying this, right?

AMY NORDRUM: Absolutely. Singapore has plans for a quantum satellite. Canada has plans. There’s been some other efforts here with ground links as well.

IRA FLATOW: There could be one up there that we don’t even know about.

AMY NORDRUM: That’s a whole other subject. It’s true.

IRA FLATOW: Let’s move on to the record, awful flooding in Louisiana. And there’s worry that that kind of flooding might become more common.

AMY NORDRUM: Right, so Louisiana has just been battered with floods. This weather that they’ve had over the last week, starting last Friday, has dropped 20 to 30 inches of rain on some areas. These are levels that we typically only see with tropical storms, tropical depressions. And the issue with this weather system was it was pulling up tropical moisture from below, and there was a low pressure system over Louisiana. And then a sort of got stuck there. It was very slow moving, so it continued to dump rain on the area for quite awhile. It could still take two to four weeks for the communities to recover and for the water tables to actually go down.

But certainly, these are the types of storms and the types of events that climate scientists have predicted happening more often, and perhaps worsening with intensity and severity due to climate change.

IRA FLATOW: Because this is called a 500 year flood, right?

AMY NORDRUM: So that is– yeah. There are areas where that’s what it’s being called. And the important thing to note with that is that terminology does not mean that it’s going to occur only once in 500 years. That’s the way a lot of people think of it. It actually means that in any given year, there’s about a one in 500 chance that it could occur. And that’s different because when you have a one in 500 chance, scientists would expect that event to occur twice over 1,000 year period. But those two times could actually be back to back. They could occur in subsequent years. So it’s not as if we have one now and then it won’t happen for another 499 years.

IRA FLATOW: Yeah, but we’ve now had 8 500 year floods in 12 months, right?

AMY NORDRUM: Right. I mean, these events are seemingly and anecdotally, based on a researcher that I spoke with from the Weather Prediction Center, happening more often. He called the frequency in the last two to three years remarkable.

IRA FLATOW: So this might be the new normal coming up now. You have a story about emergency equipment, those automatic defibrillators we all seen in public places.

AMY NORDRUM: That’s right. So these are called AEDs. And these are potentially lifesaving devices for somebody who has a cardiac arrest. And if you can get to one fast enough and use it to monitor the person’s heart rhythms and potentially administer an electric shock, their chances of survival after that event, or of lowering the damage that it would cause to their brain, for example, is much higher. So they have better odds. So you see it all over the place, in public places and in airports. But these researchers in Toronto took a look at how accessible they really are. So they monitored all the heart attacks that happened in Toronto for eight years, and then they compared that to record of AED locations throughout the city.

And they found that actually only one in five of those people who had heart attacks was within easy distance or access to an AED. And of those AEDs that were within easy distance, only maybe 80% or 70% of them were actually accessible. The rest were behind locked doors, or the building was closed, or the facility wasn’t open. And so it’s sort of raising questions about how accessible these devices and useful they really are.

IRA FLATOW: So what’s the point of having the AED if you can’t get to it?

AMY NORDRUM: Well you could certainly make an argument that for those one in five people who did have one nearby, that’s an extremely valuable device to have access to. But you could also ask whether we could do a better job of making these more accessible.

IRA FLATOW: And finally, there’s a story, news about being the self checkout lanes. Fascinating.

AMY NORDRUM: So I love these. I use them whenever possible. But apparently, some researchers in England took a look at what it means for retailers, because when shoppers can just speed through, there might be more of a tendency to just skip checking that last item and just throw it in the bag. And what they found is actually stores that had implemented this, they audited a million shopping trips over the course of their study. And they found that the loss rate was about 4%. So retailers were losing about 4% of their revenue. That’s about twice of what you’d expect with normal checkout lines.

So either people can’t figure out how to use the system, or they’re potentially shoplifting more often.

IRA FLATOW: Because there are people– I always see that there are supervisors hanging around to help you out, or maybe to keep track of what you’re putting in the bag.

AMY NORDRUM: Right, that’s true. But they don’t really have an easy time looking at everybody and monitoring exactly what you’re doing. So there’s a theory that the researchers who did this study came out with, and they’re saying, it might just be easier to shoplift, in a way, because you’re able to make excuses even if you are caught. So you’re able to say, oh, I didn’t realize I didn’t check that out. Oh, the system didn’t work correctly. I wasn’t sure how to use it. So there could be something psychological going on there.

IRA FLATOW: I miscounted the amount of items in the bag.

AMY NORDRUM: Exactly. Exactly.

IRA FLATOW: I forgot to scan the last two. I lost track. Fascinating. Thank you, Amy.

AMY NORDRUM: Thank you.

IRA FLATOW: Amy Nordrum, Associate Editor of the IEEE Spectrum here in New York.

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