MICHIO KAKU: I love to watch science fiction movies but I cringe, I cringe whenever I see a depiction of the aliens. First of all, the aliens speak perfect English.

ALIENS: Did you ever see such jerky looking creatures? And one head yet. Typical Earth men.

MICHIO KAKU: I mean, we have Hollywood special effects so why can't we get better aliens?

E.O. WILSON: I would admonish scriptwriters for Hollywood films that have space and alien monsters invading Earth. Don't give them claws. Claws are for carnivores and you've got to be an omnivore to be an ET. There just isn't enough energy available in the next trophic level down to maintain big populations and stable populations that can evolve civilization.

JONATHAN B. LOSOS: Some people have gone so far as to say that, in fact, human type organisms, humanoids will occur on other planets. So there will be intelligent beings that if we saw them they would be recognizable which, of course, is what Hollywood tells us. If you watch almost any science fiction TV show or movie the intelligent life form is bipedal, a couple of arms, a mouth. Maybe they only have three fingers and pointy ears and they're green but they're pretty humanoid. And so some people say yes, that's actually very likely that humans are a very successful life form here on Earth that we are extremely well adapted to our environment which ancestrally was occurring on the plains of Africa, but we adapted so exquisitely that we now dominate the world. So if this is such a good adaptation here on Earth it would similarly be a good adaptation on another planet and evolution would be likely to take the similar course. That is the argument that is being made in some corners.

KAKU: But when we look at aliens in the movies we're basically projecting our own consciousness in aliens. Our fears, our desires are projected and they are a mirror of who we are, not a mirror of who they really are. For example, if you take a look at a bat or a dog, the dog's brain is mainly interested in smells. It's swirling in a universe of smells while a bat's brain mainly is concentrated on sonar, on detecting clicks and echoes. The same thing with the dolphin brain. Their consciousness is totally different from our consciousness because they see things differently than us because of their evolutionary history. For example, when we see a cat and the cat comes up to us and starts to purr next to us we say to ourselves oh, nice cat. Cat is being affectionate. No, the cat is not being affectionate. It's simply rubbing its hormones on you and saying I own this human. This human is mine. I'm marking my territory. This human feeds me twice a day. I've trained him. So a cat sees the universe totally different than we do and yet we impose our thinking on an alien.

WILSON: ET is out there. There just has to be in that hundred million star system. Here's what I did. I looked over the many examples of the origin of whole new lines of animals that have occurred on the land since the early Paleozoic. Here is what they all have in common. First, it has to be on the land. It can't develop advanced societies and anything like civilization. Well, why not? Why no marine fresh water creatures? Because they don't have fire. In order to build tools beyond chipping some rock or stone away you don't have any way to create more advanced technology without concentrated power source that you can transport from one place to another. ET. I'm now drawing this again from the record of multiple origins of animal lines on Earth. ET has got a head and the head is up front and the head contains central organizing centers for all of the senses that are spread out through the body. ET has got a small number of limbs, multiple, maybe six. Who knows? Maybe eight like a spider. But not that many. Relatively few and ET has on these limbs fingers or tentacles, something with strength and flexibility that are free. You have to have soft, pulpy fingertips. Think about the primates you know. Old world and new world. That's a primate trait. Soft, pulpy fingertips. You need to be able to manipulate bits of food like plucking free a piece of fruit. Plucking seeds out of a fruit. Taking a flower and opening it and eating it and so on.

KAKU: Now some people say that we should not try to make contact with them because they could be potentially dangerous. [Danger Will Robinson. Danger.] For the most part I think they're going to be peaceful because they'll be thousands of years ahead of us but we cannot take the chance. So I personally believe that we should not try to advertise our existence to alien life in outer space because of the fact that we don't know their intentions. Then the other question is what happens if they're evil? Well, I think the question of evil is actually a relative question because the real danger to a deer in the forest is not the hunter with a gigantic rifle. He's not the main danger to a deer in the forest. The main danger to a deer in the forest is the developer. The guy that's going to pave the forest and perhaps destroy whole ecosystems. In other words, the aliens don't have to be evil in order to be dangerous to us. They might not care. They just may not care about us and in the process pave us over. And so I think that is a potential problem. We could be in the way of a very advanced civilization that simply is not evil but simply views us as we would view squirrels and deer in the forest. So, personally I think that we should not advertise our existence when we go into outer space. For the most part however, I do think they are going to be peaceful. They're not going to want to plunder the earth because there are plenty of planets out there that have nobody on them that they could plunder at will without having to worry about restive natives called humanity. And so I think they're not going to come to visit the earth to plunder us, to do all sorts of mischief. For the most part I think they'll just leave us alone.

BILL NYE: I don't think they're going to visit. However, very reasonable that we will in Carl Sagan fashion detect a signal from some other star system. That's very reasonable. I make no guarantees. It's the Christmas light problem, the holiday light problem where the lights are blinking. Our light of being able to receive electromagnetic wave from another civilization has to be on when another blinking civilization light is on so that we can cross paths not only in space but in time. We have to have both civilizations existing at the same time. And with a universe that's at least 13.6 billion years old it's not necessarily a given thing that everybody their lights will be on at the same time.

LOSOS: What would life be like on other planets if it is evolved? Would it be like the world today here on Earth or would it be completely different? This question has taken on some increased urgency or at least interest in recent years because we now realize that there are many planets out there that are like Earth. We used to think that Earth was perhaps unique and so perhaps life as we know it is unique because we're the only place that it could evolve. But quite the contrary. We've now discovered there are lots of what are called habitable exoplanets. Some people estimate millions, even billions just in our own Milky Way Galaxy. If there are really that many Earth-like planets many people think that it's very likely that life has evolved on them. And so the question is what will that life look like?

NYE: It's very reasonable, absolutely not proven. We may have the means to prove it, very reasonable that you and I are descendent of extraterrestrials. We just found liquid water on Mars. Super salty water on Mars that apparently flows every Martian year, every time Mars goes around the sun and gets warm enough in this one area liquid water flows for a while. Briny water evaporates. It's very reasonable that there's something alive on Mars or certainly that there was something alive on Mars. Then it's very reasonable that Mars was hit with an impact. You can show that Mars was hit with an impactor, a comet or asteroid, about three billion years ago. And some of the material of Mars was thrown off into space and some of it landed here. We find rocks on Earth that are clearly of Martian origin. I bought one online for kicks and suppose some especially robust Martian microbe, a Mars-crobe, was in this piece of material, landed on Earth at an especially fertile time here on Earth three billion years ago. And you and I are descendants of Martians. Do-do-do-do, do-do-do-do.