Sci-fi flicks like Alien, Independence Day, and Signs all show the terrifying alien monsters that could exist on other planets.

Some experts say these movies may not be so far from the truth.

"Considering the diversity of microbes on Earth, it wouldn't surprise me at all to find microbes on other planets," said Charles Fisher, professor of biology.

Fisher does not do work dealing specifically with life on other planets, but he does work in environments similar to those that many think might exist on other planets.

These environments are deep-sea hydrothermal vents, also known as undersea volcanoes.

Fisher chairs the Ridge 2000 Program, which is sponsored by the National Science Foundation.

The program studies the links between planetary processes such as sea floor spreading and life.

"The catch phrase for the Ridge 2000 program is 'from mantel to microbe,' " Fisher said.

In the deep sea there are strange animals and primitive microbes that live in the hydrothermal environment on the ocean floor, he said.

There are many different types of primitive bacteria and archaebacteria that are specialized for extreme environments, he added.

These extreme environments include high temperature, high salt and high pressure environments.

They also include environments where there is no oxygen and even those that contain toxic metals, Fisher added.

It is currently thought that the moons of some planets, such as Jupiter's moon Europa, may have a liquid ocean underneath a frozen crust.

"There is evidence that there may be volcanoes on the sea floor there," Fisher said.

"If this turns out to be true then the same environment exists on Europa that I study in the deep sea here on Earth."

"In fact, some scientists believe that life on Earth originated in deep sea hydrothermal vent environments, which is another reason I would not be surprised if life is discovered in similar environments on other planets or moons," he added.

There also are scientists that think life may have originated in the same environment that fishers study in the deep sea, and these environments exist on other planets, Fisher said.

"Liquid water is one of the key elements for life to evolve," Fisher said.

"If we find liquid water and energy sources, there is definitely the possibility of life on other planets."

Fisher thinks that the discovery of life on other planets would have profound implications with respect to our worldview.

"Many people think that the humans and the Earth are the center of the universe," he said.

"People will have to re-evaluate their views and ideas."

Steinn Sigurdsson, professor of astronomy, also believes that there is a high possibility that life could exist on other planets.

"The odds are not bad at all," said Sigurdsson, who works with problems with different planets in the solar system. His research involves looking for different planets, where you can expect to find them and even how they are made.

Although Sigurdsson believes there is a possibility of life on other planets, there is no proof, he said.

"It is very likely that in the next 20 years we will find planets suitable for life and some indication of whether there is life on them or not," Sigurdsson said.

An example of this would be finding evidence of life on Mars, for instance, even if it were life that existed in the past.

NASA is in the process of designing a satellite called the terrestrial planet finder.

Its purpose is to find planets like Earth and to try to analyze them and see if they have atmospheres like Earth, including water and oxygen, Sigurdsson said.

"Basically, the satellite will look for, crudely speaking, green planets," he added.

"It will look for the chemistry of the planet's atmosphere and whether or not it is capable of having life there -- life as we know it."

The satellite is still in the design process, and most likely won't be seen until 2015 or 2018, he added.

Ahmed Khalaf (senior-petroleum engineering) said he is unsure about whether or not there could be living creatures that currently exist on other planets.

"I think that microbial life might exist, for example, on Mars where the atmosphere could possibly sustain life, but we have to rule out that assumption until we actually get proof that there is life on other planets," Khalaf said.

"We can't really keep wondering."

Brandt Aiello (senior-integrative arts) also is unsure about the possibility of life existing on planets other than the Earth.

"Basically I've had no proof to believe definitely that there is life on other planets," Aiello said.

"But, I have no proof that life doesn't exist on other planets. There is always a possibility."

Leah Fietelson (senior-journalism) said she strongly believes in the possibility that life may already exist outside our solar system or on other planets.

"I feel like some sort of life has to exist on other planets, but we just haven't discovered it yet," Fietelson said. "It would be naive of us to think that we are the only living things in the universe."