IRA FLATOW: This is Science Friday. I’m Ira Flatow. A bit later in the hour, the wonderful world of everything– and I mean everything– we don’t know about the universe. Physics, philosophy, and the nature of everything. You’ll see. We’ll talk about it.

But look down at your hand. Are you holding a cell phone right now? If it’s not there, it’s probably in your pocket or at least within arm’s reach. Right?

These days, most people are never more than a few feet away from their phones, sometimes just a few inches. And scientists have studied whether long-term exposure to cell phone radiation could have an adverse impact on human health, even though there’s no strong evidence to suggest that these devices are unsafe.

But last week, the California Department of Public Health issued guidelines that seemed to alarm people. With me to discuss the ramifications of the California guidelines, as well as other short subjects in science, is Sophie Bushwick, Senior Editor for Popular Science. Hi, Sophie. Welcome back.

SOPHIE BUSHWICK: Thanks.

IRA FLATOW: So California guidelines about how to reduce exposure to cell phone radiation. Doesn’t say that it definitely causes cancer or other illnesses, but people have sort of interpreted it that way.

SOPHIE BUSHWICK: Right. I mean, the fact that they’ve issued guidelines saying, here’s how to reduce your cell phone exposure, seems to indicate that cell phone exposure is a problem. Whereas in reality, I think the scientific consensus right now is they haven’t found a strong connection between exposure to cell phone radiation and brain cancer or other health problems. But they have said that we need to keep studying this issue in the long term.

IRA FLATOW: So the people who are anti-cell phone radiation exposure– they jumped on this to say, see, we’re right?

SOPHIE BUSHWICK: Right. Some people I think have. They’ve said, look, this is vindication. But I think that for that reason, the guidelines are a little misguided. Because it’s creating a lot of fear around an issue that we’re not sure people actually need to be afraid of.

And I think really, the biggest health hazard that cell phones cause is a real health hazard, and that’s texting and driving. And texting and driving has killed and will kill far more people than brain cancer caused by cell phone radiation. So I think that if people are trying to find an issue to worry about, then that’s what they should be focusing on.

IRA FLATOW: A bigger issue, yeah. OK. Let’s move on to some strange animal behavior involving macaques in central Japan. Incidentally, monkeys are getting a little frisky with their neighbors?

SOPHIE BUSHWICK: That’s right.

IRA FLATOW: The deer? Tell us what’s going on here.

SOPHIE BUSHWICK: So for a while, people have noticed that these Japanese macaques like to ride on the sika deer that live in the region. But in the past few years, researchers have noticed a couple of dozen cases of adolescent female macaques jumping on the deer and then moving their pelvises back and forth in a sexual manner. And they have also noticed that when this happens, when the female macaques try to do this to female deer or to adolescent male dear, the deer tend to buck them off. But when they jump on fully grown male deer, they seem to let them be.

IRA FLATOW: Boy. So we don’t know the reason for the difference.

SOPHIE BUSHWICK: We’re not sure why only some of the deer accept it. Because most of the deer accept the monkeys riding on them, because that’s sort of a mutually beneficial arrangement. The monkeys will pick skin parasites like nits off the deer while they’re up there, so the deer get something out of the exchange.

IRA FLATOW: Why would a monkey try to procreate with a deer? I mean–

SOPHIE BUSHWICK: Right. It’s a weird question, but the fact is that interspecies sex does happen in the animal kingdom. So you’ve got it sometimes between similar animals, like horses and donkeys creating mules. But you also have this between completely dissimilar species. In the Antarctic, they’ve observed seals getting it on with penguins. So I think this just sort of shows that animals like sex, and they’re indiscriminate about it at times.

IRA FLATOW: I know some puppies on your legs sometimes are sort of doing the same thing.

SOPHIE BUSHWICK: Exactly.

IRA FLATOW: So we know. We also have some new information about the interstellar object that visited us a few months ago. Oumuamua– did get that right?

SOPHIE BUSHWICK: Oumuamua.

IRA FLATOW: Oumuamua. Why do they call it that, first of all?

SOPHIE BUSHWICK: It’s a Hawaiian word that means “scout,” which is certainly fodder for conspiracy theorists. It was first observed by a Hawaiian observatory. But I think the subject is fascinating.

Some people are saying, oh, it’s an alien probe. And it’s probably not an alien probe, but what it is is still really cool. So the latest observations have researchers now think that it has– it’s this cigar-shaped object about 700 feet long. That’s about two football fields in length. And they think its core is made out of ice. And it’s insulated with this outer layer of goo, this carbon-based material that surrounds the ice and insulates it so that it can travel through our solar system without that icy heart melting.

IRA FLATOW: Ah. So it’s a thick coating, sort of a space snot, like, zoof!

SOPHIE BUSHWICK: [LAUGHING] Yes, it’s like a really gross layer of space snot. They think that what happened was this object used to be coated in a carbon dioxide ice, sort of like dry ice, and that as it traveled through interstellar space– I mean, this is an object that’s about 100 million years old. So it’s had lots of years of traveling through interstellar space. And the cosmic radiation around it broke down that icy outer layer and turned it into this space snot, as you call it.

IRA FLATOW: So it’s gone now, right? It is not alien life or something like an alien space ship, what people were talking about it as.

SOPHIE BUSHWICK: We don’t think it’s an alien spaceship. And it’s zipped past us. It’s actually traveling away from us at 27 miles per second, so a marathon every second.

IRA FLATOW: Finally, there is this study that shows that kids think birthday parties are what makes them get older.

SOPHIE BUSHWICK: This is, I think, the cutest study I’ve heard about this year. Yes, so little kids– they think that the mechanism that makes them get a year older is the actual birthday party itself. So this is a new study looking at American children, but previous studies have found this in Israeli children.

And basically, what happens is when kids are born, they don’t have a sense of time as a continuum. So they have to learn that it is. They don’t think, oh, I was three and then a year passed and so now I have turned four. They think, today I am four. Thus it must be the party that I’m having today that’s turning me four.

IRA FLATOW: Oh, it’s the party. So they wait for the party. Because their mom or dad is saying, hey, you’re not four yet. That’ll happen on Saturday when we have the party.

SOPHIE BUSHWICK: Exactly. And so they think, oh, it’s the party that’s done it.

IRA FLATOW: [LAUGHING] It’s not?

SOPHIE BUSHWICK: [LAUGHING] Well, I just think it’s fascinating. We think of time as– we have this very intuitive sense of what time is, how much time passes in an hour.

And we forget that when we were little, we didn’t have this sense. We weren’t born with it. We learned it, and then it became such an ingrained part of our minds that we think we’ve always known it.

IRA FLATOW: You know physicists, so we’re going to talk about this later, talk about time. Still trying to figure out how time works.

SOPHIE BUSHWICK: Right. We just make all these assumptions about time. When you actually start thinking about it, questions like, why does time only flow forward, all of a sudden become really relevant and interesting.

IRA FLATOW: Hang around for the rest of the hour. Sophie, have a good holiday.

SOPHIE BUSHWICK: Thanks. You, too.

IRA FLATOW: Sophia Bushwick, Senior Editor for Popular Science.

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