 argues that in his paper (LINK). I don’t suggest you read it, since he gives away all the spoilers in the Abstract. The relevant quote about the Fermi Paradox is:https://arxiv.org/PS_cache/hep-th/pdf/0702/0702178v1.pdfThus, if we know only that we are living in a pocket universe that satisfies Eq. (12), it is extremely improbable that it also satisfies Eq. (13). We would conclude, therefore, that it is extraordinarily improbable that there is a civilization in our pocket universe that is at least 1 second more advanced than we are. Perhaps this argument explains why SETI has not found any signals from alien civilizations, but I find it more plausible that it is merely a symptom that the synchronous gauge probability distribution is not the right one.Translation: This result makes no sense. Intelligent civilizations are too far apart in space or time: Yes, but they can cross the entire galaxy in a few million years. Unless no civilization ever does this, we should see something. An interstellar Outback® or Jimmie Johns™ on Mars. Something. I’m calling this unlikely. It is too expensive to spread physically throughout the galaxy: Time is on your side, and something like a self-replicating robot could easily get through the galaxy in a million years and spend time creating “My Robot Went to Cygnus X-1 and Only Got Me This Lousy T-Shirt” t-shirts for the inevitable tourist trade. This is nearly within our ability, so, unlikely. Human beings have not listened long enough: This is a good point. We’ve only been able to listen for the last 80 years or so, and most of the time we weren’t listening. Unless the aliens bought commercial air time during the Super Bowl®, they could have been broadcasting instructions on how to build an interstellar drive for a space ship or how to make creamy PEZ® and we would never have heard. We are not listening properly: My first grade teacher accused me of this. In writing. On my report card. “Johnny likes to talk and can’t sit still.” That’s because I was a boy, silly. That’s on the warning label, along with the bruises, cuts, and torn jeans. But back to aliens. We listen on the radio spectrum, mostly. And mostly on a particular spectrum, as defined by the Search for ExtraTerrestrial Intelligence (SETI) Institute’s website (below). What if that’s just a convenient place to look, and not the one aliens have settled on? What if they use lasers, or the even more potent laser/shark method? What if they text? What if they use fundamentally different timescales (much slower or faster)? This is likely, in my opinion.BLOCKQUOTEFor interstellar communication, a particular range of radio frequencies, “microwaves” from 1 GHz to 10 GHz, are particularly good choices. At lower frequencies our galaxy emits prodigious amounts of radio waves creating a loud background of noise. At higher frequencies the Earth’s atmosphere, and presumably the atmosphere of other Earth-like planets, absorbs and emits broad ranges of radio frequencies. The result is a quiet “Microwave Window” through which efficient radio communication is possible. https://imgs.xkcd.com/comics/the_search.pngFrom XKCD Civilizations broadcast detectable radio signals only for a brief period of time: This was (kinda) my theory in 2000 when I emailed Frank Drake (LINK) and asked him – (his equation-The Drake Equation-is used to estimate the number of civilizations communicating in the galaxy). In short, my hypothesis was that civilizations must have sufficient excess energy to spend the time and effort to broadcast to space and to listen for signals from space, and that having that excess energy from (like us) hydrocarbons like oil and natural gas and coal only last for a while. And fusion is hard, and fission has waste problems. A related post of mine is here (LINK). Drake responded, and, sadly, that email account is no longer or I’d quote the response. In one word, his answer was, “maybe.” The other concept is that civilizations are “noisy” for a while until they learn to move on from high powered radio to lots of smaller low-power radios. Earth has gotten a lot quieter since the 1970’s. https://imgs.xkcd.com/comics/the_drake_equation.png)
“Morty, there’s nothing dishonest about what we’re doing. Now slap on these antennae. These people need to think we’re aliens.” – Rick and Morty
What an alien might look like. Perhaps a bit too subtle in the orange suit?
“Where is everybody?”
That’s the simple question that Enrico Fermi asked at lunch in 1950 at the Los Alamos National Laboratory. Everybody laughed, because on the walk to lunch, these eminent physicists (Edward Teller, father of the hydrogen bomb was one) had been talking about UFOs, and his comment a half hour later seemed to capture the idea that all of them had. To my knowledge, none of these eminent men (except for Teller) lived in Mom’s basement or wore tinfoil underwear to bed, so it was a serious question asked by seriously smart dudes:
Where are the aliens?
Eventually this question became the foundation for what’s known today as the “Fermi Paradox.” Stated simply, the Fermi Paradox says:
- The galaxy has been around for billions of years so,
- It’s unlikely that we’re the first civilization,
- A civilization should be able to move across a galaxy in millions of years, so
- Why don’t we hear them or see them? Why aren’t they in our solar system? Is the food that bad here?
Thankfully, a large number of people (some of whom also live in their Mom’s basement) have spent a lot of time thinking about this. Per Wikipedia (LINK), here are the best answers:
- Extraterrestrial life is rare or non-existent: This is the first explanation. But it’s lame. Really lame. Everywhere we look in interstellar space, we see signs of chemicals that are clearly precursors to life. And life showed up pretty quickly on Earth, and perhaps even earlier on Mars. I don’t buy this one. If you’ve seen the inside of my fridge, you know that life is everywhere.
- No other intelligent species have arisen: I have to give this one a possibility. As far as we know, intelligent, tool making life has existed only for 0.01% of the lifetime of the planet. That’s not a lot of time. Could it be that intelligence beyond a certain point actually results in an evolutionary disadvantage? Maybe all the intelligent lizard-people were eaten by Tyrannosaurus Rex while arguing that the means of production should be shared by all dinosaurs, and that T. Rex was a greedy member of the 1%?
From XKCD.
- Intelligent alien species lack advanced technology: I can see lots of ways this could be. A planet with low metal content so no circuits. It’s pretty hard to build a bamboo radio telescope that works. For that you also need kelp, and an electric eel.
- It is the nature of intelligent life to destroy itself: Are you talkin’ to me? Hmm? Well, I’m the only one here. I thought so. I looked up the main causes of death in the world in 2015. People killing people was not in the top 10. So, while it might be fun to beat up on yourself and on how bad humanity is, that’s simply not the case. Mankind rocks.
- It is the nature of intelligent life to destroy others: With a sample size of zero, it’s hard to say one way or another. Even a small number of alien species bent on destruction of all other species would be significant. But wouldn’t we have seen a sign of that, like a big moon gun shooting at us?
- Periodic extinction by natural events: It’s undeniable that happens here on Earth. There have been five mass extinctions, with the most recent being 65,000,000 years ago, which is longer than many people live, so you might not remember it. It’s the one that killed all the dinosaurs, remember them?
- Inflation hypothesis and the youngness argument: This one is bogus. Even the author (Future Nobel Prize Winner Dr. Alan Guth) argues that in his paper (LINK). I don’t suggest you read it, since he gives away all the spoilers in the Abstract. The relevant quote about the Fermi Paradox is:
Thus, if we know only that we are living in a pocket universe that satisfies Eq. (12), it is extremely improbable that it also satisfies Eq. (13). We would conclude, therefore, that it is extraordinarily improbable that there is a civilization in our pocket universe that is at least 1 second more advanced than we are. Perhaps this argument explains why SETI has not found any signals from alien civilizations, but I find it more plausible that it is merely a symptom that the synchronous gauge probability distribution is not the right one.
Translation: This result makes no sense.
- Intelligent civilizations are too far apart in space or time: Yes, but they can cross the entire galaxy in a few million years. Unless no civilization ever does this, we should see something. An interstellar Outback® or Jimmie Johns™ on Mars. Something. I’m calling this unlikely.
- It is too expensive to spread physically throughout the galaxy: Time is on your side, and something like a self-replicating robot could easily get through the galaxy in a million years and spend time creating “My Robot Went to Cygnus X-1 and Only Got Me This Lousy T-Shirt” t-shirts for the inevitable tourist trade. This is nearly within our ability, so, unlikely.
- Human beings have not listened long enough: This is a good point. We’ve only been able to listen for the last 80 years or so, and most of the time we weren’t listening. Unless the aliens bought commercial air time during the Super Bowl®, they could have been broadcasting instructions on how to build an interstellar drive for a space ship or how to make creamy PEZ® and we would never have heard.
- We are not listening properly: My first grade teacher accused me of this. In writing. On my report card. “Johnny likes to talk and can’t sit still.” That’s because I was a boy, silly. That’s on the warning label, along with the bruises, cuts, and torn jeans. But back to aliens. We listen on the radio spectrum, mostly. And mostly on a particular spectrum, as defined by the Search for ExtraTerrestrial Intelligence (SETI) Institute’s website (below). What if that’s just a convenient place to look, and not the one aliens have settled on? What if they use lasers, or the even more potent laser/shark method? What if they text? What if they use fundamentally different timescales (much slower or faster)? This is likely, in my opinion.
For interstellar communication, a particular range of radio frequencies, “microwaves” from 1 GHz to 10 GHz, are particularly good choices. At lower frequencies our galaxy emits prodigious amounts of radio waves creating a loud background of noise. At higher frequencies the Earth’s atmosphere, and presumably the atmosphere of other Earth-like planets, absorbs and emits broad ranges of radio frequencies. The result is a quiet “Microwave Window” through which efficient radio communication is possible.
From XKCD
- Civilizations broadcast detectable radio signals only for a brief period of time: This was (kinda) my theory in 2000 when I emailed Frank Drake (LINK) and asked him – (his equation-The Drake Equation-is used to estimate the number of civilizations communicating in the galaxy). In short, my hypothesis was that civilizations must have sufficient excess energy to spend the time and effort to broadcast to space and to listen for signals from space, and that having that excess energy from (like us) hydrocarbons like oil and natural gas and coal only last for a while. And fusion is hard, and fission has waste problems. A related post of mine is here (LINK). Drake responded, and, sadly, that email account is no longer or I’d quote the response. In one word, his answer was, “maybe.” The other concept is that civilizations are “noisy” for a while until they learn to move on from high powered radio to lots of smaller low-power radios. Earth has gotten a lot quieter since the 1970’s.
From XKCD
- They tend to isolate themselves: It could be that the alien species are all introverts that like spending time in their room listening to music, or standing in the corner at a party until they sneak out and go home and hit the Playstation®.
- They are too alien: Aliens might be so different than us that we cannot mutually communicate – ever. It would be like meeting a civilization composed entirely of ex-wives (or ex-husbands, your choice). Hey, maybe that was why they called it the eX-Files®?
- Everyone is listening, no one is transmitting: Like us. We’re not actively sending signals out, or at least not very often. If someone did hear us, they’d look back to see if there was a signal, and they wouldn’t find a thing.
- Earth is deliberately not contacted (zoo): We’re like the hippos in the zoo. People look, but you’re not supposed to disturb the display. Oh, look what happens when you throw a hurricane at them! Silly people! Possible, but seems like a lot of work.
- Earth is purposely isolated (prank): Let’s take a civilization, and make it look like nothing’s going on outside their solar system (snicker). And let’s magic marker their face. Seems very unlikely, and way too much effort.
- It is dangerous to communicate: Maybe everybody looks out and says . . . “Where is everyone?” Since there’s no good answer, they assume everyone before them got smashed by . . . something out there. So, they shut up. Maybe? It’s what Hawking is suggesting as our best strategy now.
- The Simulation Theory: We live in a simulation, and they didn’t program in any aliens. Very possible. Our current level of technology could almost produce a realistic simulation, so it’s not too far off to expect that another million years of tech advancement would produce not only SuperUber with cabs that all driven by clones of NFL® legend Howie Long, but the ability to live your entire life in your Mom’s basement in a virtual reality. And we’re all non-player characters.
- They are here undetected: They’re sneaky, and are all over, like tourists, and we just don’t know it. Some silly Prime Directive or something. I believe this is unlikely, because Kirk always ignored the Prime Directive whenever it was even remotely convenient.
- They are here unacknowledged: This is the true X-Files® X-Planation. Government knows. SETI™ knows. Nobody will tell us. This is one of the most popular with the tinfoil-wearing basement dwellers. It’s solidly possible. Blue Oyster Cult certainly thinks so:
1980’s at its best: men in black, bad special effects, girls in furs, weird beards, and Flight 19 references.
What about . . . we are the aliens? If you look at life . . . it’s got great computational power. It’s got amazing resiliency to everything from meteor bombardment to super volcanos. It has amazing memory storage capacity (think the amount of info in DNA alone). It’s complex, but resilient. Perhaps the galaxy has been seeded, with us and the things that live in my fridge. And we’re the replicating critters that are supposed to send copies out into the cosmos.
When we manage to get out of Mom’s basement.
