# Are we alone in the universe? New Drake equation suggests yes

## A fresh take on the decades-old Drake equation incorporates new factors and greater uncertainty, suggesting a high likelihood that humanity is alone in the universe.

At the Los Alamos National Laboratory in 1950, physicist Enrico Fermi famously posed to his colleagues a simple question borne of complex math: ‘Where are they?’

He was asking about aliens—intelligent ones, specifically. The Italian-American scientist was puzzled as to why mankind hasn’t detected any signs of intelligent life beyond our planet. He reasoned that even if life is extremely rare, you’d still expect there to be many alien civilizations given the sheer size of the universe. After all, some estimates indicate that there is one septillion, or 1,000,000,000,000,000,000,000,000, stars in the universe, some of which are surrounded by planets that could probably support life.

So, where are they, and why aren’t they talking to us?

This is known as the Fermi paradox. It’s based on mathematical ideas like the Drake equation, which was devised to estimate the number of detectable civilizations in the Milky Way. Scientists use the equation by multiplying seven variables, as Elizabeth Howell outlined for Space:

*N = R* • fp • ne • fl • fi • fc • L*

- N = The number of civilizations in the Milky Way Galaxy whose electromagnetic emissions are detectable.
- R* = The rate of formation of stars suitable for the development of intelligent life.
- fp = The fraction of those stars with planetary systems.
- ne = The number of planets, per solar system, with an environment suitable for life.
- fl = The fraction of suitable planets on which life actually appears.
- fi = The fraction of life bearing planets on which intelligent life emerges.
- fc = The fraction of civilizations that develop a technology that releases detectable signs of their existence into space.
- L = The length of time such civilizations release detectable signals into space.

The Drake equation is incredibly speculative, or, as astronomer Jill Tarter once said, it’s “a wonderful way to organize our ignorance.” It remains a puzzling problem.

However, a new paper from scientists at the Future of Humanity Institute at Oxford University provides an updated Drake equation, one that incorporates “realistic distributions of uncertainty” and “models of chemical and genetic transitions on paths to the origin of life.” By doing so, the researchers say they dissolve the Fermi paradox and provide even more reason to think we’re alone in the universe.

The updated equation effectively takes each variable and combines many historical estimates that scientists have used to create an uncertainty range, one that highlights just how much scientists still don’t know, as study author Anders Sandberg told Universe Today:

“Many parameters are very uncertain given current knowledge. While we have learned a lot more about the astrophysical ones since Drake and Sagan in the 1960s, we are still very uncertain about the probability of life and intelligence. When people discuss the equation it is not uncommon to hear them say something like: 'this parameter is uncertain, but let’s make a guess and remember that it is a guess', finally reaching a result that they admit is based on guesses.

"But this result will be stated as single number, and that anchors us to an *apparently* exact estimate—when it should have a proper uncertainty range. This often leads to overconfidence, and worse, the Drake equation is very sensitive to bias: if you are hopeful a small nudge upwards in several uncertain estimates will give a hopeful result, and if you are a pessimist you can easily get a low result.”

After Sandberg and his colleagues combined these uncertainties, the results showed a distribution pattern of the likelihood that humanity is alone in space.

“We found that even using the guesstimates in the literature (we took them and randomly combined the parameter estimates) one can have a situation where the mean number of civilizations in the galaxy might be fairly high—say, a hundred—and yet the probability that we are alone in the galaxy is 30%! The reason is that there is a very skew distribution of likelihood.

“If we instead try to review the scientific knowledge, things get even more extreme. This is because the probability of getting life and intelligence on a planet has an *extreme* uncertainty given what we know—we cannot rule out that it happens nearly everywhere there is the right conditions, but we cannot rule out that it is astronomically rare. This leads to an even stronger uncertainty about the number of civilizations, drawing us to conclude that there is a fairly high likelihood that we are alone. However, we *also* conclude that we shouldn’t be too surprised if we find intelligence!”

Scientists have devised a number of hypotheses to address the Fermi paradox, including ones that argue aliens have never existed; interstellar communication is technologically impossible; aliens are intentionally concealing themselves from us; and, perhaps most disturbing, that all intelligent species end up annihilating themselves before settling other planets.

So, what do Sandberg and his colleagues think about Fermi’s famous question: ‘Where are they?’

They wrote that aliens are “probably extremely far away, and quite possibly beyond the cosmological horizon and forever unreachable,” adding that their distribution shows a 39 percent to 85 percent chance that humans are alone in the universe.

But that’s not to say they think scientists should give up on the search for intelligent alien life.

“What we are not showing is that SETI is pointless—quite the opposite!” Sandberg said. “There is a tremendous level of uncertainty to reduce. The paper shows that astrobiology and SETI can play a big role in reducing the uncertainty about some of the parameters. Even terrestrial biology may give us important information about the probability of life emerging and the conditions leading to intelligence. Finally, one important conclusion we find is that lack of observed intelligence does not strongly make us conclude that intelligence doesn't last long: the stars are not foretelling our doom!”

## Why the number 137 is one of the greatest mysteries in physics

Famous physicists like Richard Feynman think 137 holds the answers to the Universe.

- The
**fine structure constant**has mystified scientists since the 1800s. - The number
**1/137**might hold the clues to the Grand Unified Theory. - Relativity, electromagnetism and quantum mechanics are unified by the number.

## Americans under 40 want major reforms, expanded Supreme Court

Younger Americans support expanding the Supreme Court and serious political reforms, says new poll.

- Americans under 40 largely favor major political reforms, finds a new survey.
- The poll revealed that most would want to expand the Supreme Court, impose terms limits, and make it easier to vote.
- Millennials are more liberal and reform-centered than Generation Z.

## Can you solve what an MIT professor once called 'the hardest logic puzzle ever'?

Logic puzzles can teach reasoning in a fun way that doesn't feel like work.

- Logician Raymond Smullyan devised tons of logic puzzles, but one was declared by another philosopher to be the hardest of all time.
- The problem, also known as the Three Gods Problem, is solvable, even if it doesn't seem to be.
- It depends on using complex questions to assure that any answer given is useful.

### The Three Gods Problem

<iframe width="730" height="430" src="https://www.youtube.com/embed/UyOGZk7WbIk" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe><p> One of the more popular wordings of the problem is:<br> <br> "Three gods A, B, and C are called, in no particular order, True, False, and Random. True always speaks truly, False always speaks falsely, but whether Random speaks truly or falsely is a completely random matter. Your task is to determine the identities of A, B, and C by asking three yes-no questions; each question must be put to exactly one god. The gods understand English, but will answer all questions in their own language, in which the words for <em>yes</em> and <em>no</em> are <em>da</em> and <em>ja</em>, in some order. You do not know which word means which."<br> <br> Boolos adds that you are allowed to ask a particular god more than one question and that Random switches between answering as if they are a truth-teller or a liar, not merely between answering "da" and "ja." <br> <br> Give yourself a minute to ponder this; we'll look at a few answers below. Ready? Okay. <strong><br> <br> </strong>George Boolos' <a href="https://www.pdcnet.org/8525737F00588A37/file/31B21D0580E8B125852577CA0060ABC9/$FILE/harvardreview_1996_0006_0001_0060_0063.pdf" target="_blank" rel="noopener noreferrer">solution</a> focuses on finding either True or False through complex questions. </p><p> In logic, there is a commonly used function often written as "iff," which means "if, and only if." It would be used to say something like "The sky is blue if and only if Des Moines is in Iowa." It is a powerful tool, as it gives a true statement only when both of its components are true or both are false. If one is true and the other is false, you have a false statement. </p><p> So, if you make a statement such as "the moon is made of Gorgonzola if, and only if, Rome is in Russia," then you have made a true statement, as both parts of it are false. The statement "The moon has no air if, and only if, Rome is in Italy," is also true, as both parts of it are true. However, "The moon is made of Gorgonzola if, and only if, Albany is the capitol of New York," is false, because one of the parts of that statement is true, and the other part is not (The fact that these items don't rely on each other is immaterial for now).</p><p> In this puzzle, iff can be used here to control for the unknown value of "da" and "ja." As the answers we get can be compared with what we know they would be if the parts of our question are all true, all false, or if they differ. </p><p> Boolos would have us begin by asking god A, "Does "da" mean yes if and only if you are True if and only if B is Random?" No matter what A says, the answer you get is extremely useful. As he explains: <br> </p><p> "If A is True or False and you get the answer da, then as we have seen, B is Random, and therefore C is either True or False; but if A is True or False and you get the answer ja, then B is not Random, therefore B is either True or False… if A is Random and you get the answer da, C is not Random (neither is B, but that's irrelevant), and therefore C is either True or False; and if A is Random...and you get the answer ja, B is not random (neither is C, irrelevantly), and therefore B is either True or False."<br> <br> No matter which god A is, an answer of "da" assures that C isn't Random, and a response of "ja" means the same for B. </p><p> From here, it is a simple matter of asking whichever one you know isn't Random questions to determine if they are telling the truth, and then one on who the last god is. Boolos suggests starting with "Does da mean yes if, and only if, Rome is in Italy?" Since one part of this is accurate, we know that True will say "da," and False will say "ja," if faced with this question. </p><p> After that, you can ask the same god something like, "Does da mean yes if, and only if, A is Random?" and know exactly who is who by how they answer and the process of elimination. </p><p> If you're confused about how this works, try going over it again slowly. Remember that the essential parts are knowing what the answer will be if two positives or two negatives always come out as a positive and that two of the gods can be relied on to act consistently. </p><p> Smullyan wrote several books with other logic puzzles in them. If you liked this one and would like to learn more about the philosophical issues they investigate, or perhaps if you'd like to try a few that are a little easier to solve, you should consider reading them. A few of his puzzles can be found with explanations in this <a href="https://www.nytimes.com/interactive/2017/02/11/obituaries/smullyan-logic-puzzles.html" target="_blank" rel="noopener noreferrer">interactive</a>. </p>## New tardigrade species withstands lethal UV radiation thanks to fluorescent 'shield'

Another amazing tardigrade survival skill is discovered.