Where Are the Aliens?

Images from ShutterStock. Space Age font for non-commercial use from mickeyavenue.com/fonts/spaceage/license.php.

Images from ShutterStock. Space Age font from mickeyavenue.com/fonts/spaceage/license.php.


With regard to possible extraterrestrial life in the universe, physicists Enrico Fermi and Michael H. Hart raised the question, “Where is everybody?” [Ref. 1].

This is known as the Fermi paradox.


The Fermi paradox begins with basic astronomical observations:

  • Our sun is an average star. The Milky Way galaxy in which we live is a spiral galaxy consisting of over one hundred billion (100,000,000,000) stars [Ref. 2].
  • Our galaxy is just an average-sized spiral galaxy. Astronomers estimate that there are over a hundred billion galaxies, with approximately a septillion (1,000,000,000,000,000,000,000,000; that’s 24 zeroes!) in the universe.
  • Our sun is relatively young. It’s about 5 billion years old. Scientists believe our universe to be about 14 billions years old.

It seems like there are too many stars in the universe for intelligent life not to form on many other planets. Even if the speed of interstellar travel is small compared to the speed of light, and even with the several millions of years needed for intelligent life to develop in a favorable solar system, it has been estimated that a galaxy can be colonized in a timescale on the order of tens of millions of years (which pales in comparison to the age of the universe).

But if aliens have colonized the galaxy, where are they?

That’s the Fermi paradox:

  • Statistically, it seems likely that extraterrestrial life should have colonized the galaxy, including visits to earth.
  • But there is no clear sign of alien life on earth. (Or is there?)


Several possible solutions to Fermi’s paradox have been proposed.

Most of these fall into one of two categories:

  • The conditions by which life developed on earth are extremely rare, so much so that extraterrestrials have not yet colonized our galaxy.
  • Aliens have indeed visited earth, but either our governments or the extraterrestrials themselves have prevented this from becoming widespread knowledge.


One possibility is that intelligent life is so rare that despite the huge number of stars in the universe, intelligent life is unique to earth or at least extremely rare.

Here are a couple of possible explanations which have been suggested to explain this:

  • The Great Filter [Ref. 5]. Perhaps intelligent life tends to be very short-lived, running out of needed resources, suffering from overpopulation, meeting with natural disasters or diseases, or destroying itself through wars or apocalyptic weapons.
  • Rare Earth Hypothesis [Ref. 6]. This hypothesis rejects the mediocrity principle, stating that the conditions for life on earth are quite atypical. Earth has a significant axis tilt (23.5º), a very large moon, a favorable distance to the sun, a favorable atmosphere, a moon the right distance from earth to produce significant tidal effects, etc. On top of the astronomical and geological requirements, the conditions also need to be favorable for the biology, and even under favorable conditions it might be rare for life to begin and for intelligent life to develop.


Another possibility is that aliens have indeed visited planet earth, but this knowledge hasn’t become widely publicized.

Following are some possible explanations which may explain why it hasn’t become public knowledge:

  • Zoo hypothesis. The earth might be a galactic zoo or park, for example. Just as we have national parks to preserve wildlife, the earth might be such a planetary reservation. This might be to allow earth the opportunity to continue its natural development.
  • Government cover-up. Perhaps governments are either aware of extraterrestrial visitors to earth or are actually in contact with aliens, but have covered this up from the general public.
  • Lack of interest. They may be too busy with other affairs, or too different from us, to have any interest in contacting humans on earth.
  • Too advanced. Aliens who can visit earth may be so far advanced in comparison to humans that they don’t consider it worthwhile to establish contact with us, or perhaps they fear that sharing technology at this stage in human development could threaten life on earth (we might not be ready for a sudden improvement in technology). They might be as far advanced compared to humans as humans are advanced compared to monkeys, for example.
  • Irreconcilable differences. They may be drastically different from us, making communication very challenging or not worth the effort. Even on earth, we see great diversity in life forms. Intelligent extraterrestrial life that may be able to visit earth or at least communicate via long distance may be as different to us as a giraffe is to a fish.
  • Here undetected. Aliens may be visiting earth, or even present on earth, but keeping themselves fairly undetected.


The Ancient Aliens series on the History Channel has recently popularized ancient astronaut theory.

Ancient astronaut theory and its growing popularity can be traced back to Erich von Däniken, author of Chariots of the Gods? [Ref. 7] which raises several questions about ancient civilizations, for which mainstream science may not have a convincing explanation.

Maybe aliens have visited earth in the distant past, and maybe there is evidence to show this.

Ancient astronaut theory even raises the question of whether or not modern day humans may be in some way extraterrestrial, e.g. perhaps ancient aliens had a hand in genetic development.

This idea intrigues me. In future articles, I will be searching for possible evidence of ancient aliens here on earth.


  1. “Where is everybody?” An account of Fermi’s question. Jones, E.M., 1985.
  2. “How many stars are in the Milky Way?” Howell, Elizabeth, 2014.
  3. “How many stars are there in the universe?” Cane, Fraser, 2013.
  4. “Looking back to the cradle of our universe,” JPL, 2014.
  5. “The Great Filter—are we almost past it?” Hanson, Robin, 1998.
  6. Rare Earth: Why Complex Life is Uncommon in the Universe, Ward, Peter D. and Brownlee, Donald, 2003.
  7. Chariots of the Gods, Däniken, Erich von, 1999.


Author of:

  • A Visual Guide to Extra Dimensions
  • An Introduction to Basic Astronomy Concepts
  • The Improve Your Math Fluency series of workbooks

Follow me at:


About chrismcmullen

I'm a physics instructor and self-published writer. My writing includes visual books on the fourth dimension, math workbooks, golf and chess log books, books on self-publishing, and puzzle books. Originally from one L.A. (Los Angeles), I now live in another LA (Louisiana). I have a Ph.D. in phenomenological high-energy physics, I am a passionate teacher and nonfiction writer, and I enjoy golf, Scrabble, and chess.
This entry was posted in aliens, extraterrestrials, Fermi paradox and tagged , , . Bookmark the permalink.

2 Responses to Where Are the Aliens?

  1. fxr3102 says:

    I just listened to a radio interview with Bob Lazar (that he did in 2014? on YouTube). He sounds 100% convinced that we are being visited regularly by someone from another place. I found his description of the anti gravity systems on the craft he was working on to be totally fascinating. It doesn’t sound to me like he’s making it up. He is also talking about how the US gov’t tried to erase his identity ( apparently they couldn’t because he had been mentioned in newspapers, etc, for unrelated things, before he went public).

    Anyway, I have seen a few things flying around myself, and I’m totally convinced that something is happening. BTW, Lazar says that he doesn’t think we’ll be able to copy any of these gravity reactors and amplifiers anytime soon. From what he is saying, its like what would happen if you gave a bunch of cavemen a motorcycle to try and copy. They would maybe figure out how to start it, and use it until it ran out of fuel, then that would be the end of that.

    So, I don’t quite know what the object of this reply was supposed to be, except to say that with all the activity going on, there must be something really happening out there. At least it sure looks to me like we’re being visited. Its too bad all of these yoyos like to make up stories, and fake photos and stuff. But, I know what I saw, and as far as I’m concerned, it was not from around here.

    Liked by 1 person

    • I like your motorcycle analogy. 🙂 When I look at how much our understanding of science and its applications to technology have evolved over the past century, and then I try to imagine how much technology could improve in 100, 1000, or especially 10,000 years, I think I really would feel like a caveman if I were able to look at some technology from far in the future. So if there is life out there with the technology to reach earth, it has the potential of being incredibly sophisticated.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s