How Will We (Most Likely) Discover Alien Life?

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The first discovery of extraterrestrial life will almost certainly NOT be when it visits us, nor when we visit it. It won’t be when we see it’s stray TV signals. It’ll be in the excruciatingly faint changes in the color of alien sunsets glimpsed hundreds of light years away. Today we’re going to talk about the first such hint, why it's probably not aliens, and why there’s a tiny chance that it still might not not be aliens.

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Hosted by Matt O'Dowd
Written by Matt Caplan & Matt O'Dowd
Post Production by Leonardo Scholzer, Yago Ballarini & Stephanie Faria
Directed by Andrew Kornhaber
Associate Producer: Bahar Gholipour
Executive Producers: Eric Brown & Andrew Kornhaber
Executive in Charge for PBS: Maribel Lopez
Director of Programming for PBS: Gabrielle Ewing
Assistant Director of Programming for PBS: John Campbell

Spacetime is produced by Kornhaber Brown for PBS Digital Studios.
This program is produced by Kornhaber Brown, which is solely responsible for its content.
© 2023 PBS. All rights reserved.

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[rlosable]

I find it so fascinating that we can now just measure spectra of planets' atmospheres. I remember discussing that possibility as a teenager with my dad, more than 25 years ago after reading about the idea.

He told me I was crazy and this would never happen in my lifetime. Sadly, it didn't happen in his.

[Kahnabys]

It still amazes me how fast we've progressed in the last 150 years. Also going from the first powered flight to landing on the moon in 66 years is absolutely insane.

[gregspecht]

everybody gangsta until its actually aliens

[ariesmars]

I always love it when you say, "It's never aliens, until it is." I wish more people would come to that conclusion. Too many people, say things like, "I can't explain it so it must be aliens."

[jamesrivera]

Long time watcher. I just to say thank you for always being truthful about the tentativeness of discoveries. So many YouTube channels would have made a video about the same information saying we discovered life on other planets. You guys always stay true to the science and the healthy skeptical approach. It’s appreciated.

[TheScourge]

One of the problems with finding life seems to be that the places that are easiest to look, planets close in to stars where a lot of transits can happen in a short time, are nothing like the one planet we know has life. Not that this is useless, there's a lot of science that can be done besides searching for life and if we did find life in such a different world that would be VERY eye opening about what life actually needs. But it does mean that our threshold for believing a signal is life will be higher in a system/planet that's so different from our only confirmed life.

All reminds me of this joke: You're walking down the street at night when you see a person looking on the ground under a lamp post. You ask them what's happening and they say they're looking for an earring that they just lost. So you offer to help and after looking with them a while you ask "are you sure you dropped the earring here?" The person you're with looks up surprised at the question and says "oh heavens no, I lost it over there" pointing down the street into the dark. So you respond confused "but if you dropped it over there why are we looking here?"

The searcher replies "well this is where the light is."

[thangs]

Thank you for coincidentally releasing a video on my 50th birthday, Matt and crew. I couldn't ask for a better gift. Got the day all to myself, going to see family tomorrow. I'm excited to watch this video and then dive into the Black Hole playlist for the 100th time and counting. Cheers from an old fan (holy cow I'm 50, how did this happen?) and thank you for everything you do for science.

[thomascaldwell]

Science is just freaking amazing. The things we can suss out given a good scientific framework and decent data... I'm forever amazed. On a different topic, I think we need to take steps to ensure Dr. Matt remains the host of PBS Space Time for the remainder of spacetime. Hopefully this involves interesting incentives and the like, but if not... well, the ends justify the means. Also, there's the mortality thing, but I'm sure that can be worked out as well.

[sharky]

What scifi movies will Matt watch this week?
I'm not sure, all I know is - it's never Aliens...

[ericmatthews]

In Star Trek, Spock would always announce the type of planet the Enterprise was approaching, using a single letter to indicate its classification. After watching this episode, we probably need a far more robust classification system than our 26 letter alphabet can accommodate.

[donald-parker]

I wonder how detectable life on earth would be from such a distance.

[peters]

Thanks for going through the explanation of why its thought K2-18b is thought to be a Hycean planet rather than a mini-Neptune. I haven't seen much discussion of that elsewhere and I think it's an important point. I also think calling the presence of DMS a 1 sigma detection is fair but the paper did find a higher level of confidence for DMS detection at 0 offsets, to about a 99 percent. The authors presented the data with 0, 1 and 2 offsets to account for potential error due to the gap between the two detectors that were primarily used for gathering the data. But the paper did say the 1 offset detection, which was 1 sigma, was probably the most realistic, so calling it 1 sigma, or about 68 percent probable, is probably the most fair interpretation.

[slimee]

Now sci-fi writers can write "cabbage aliens" into their words and claim some scientific accuracy, amazing

[marklee]

Honestly this is exactly and solely what just should be focused on investigating planets in Goldilocks zone. This was a fantastic episode

[Ofinfinitejest]

"It's Usually Human Delusions" - Would be the most truthful T-shirt.

[crowlsyong]

Matt and the PBS Spacetime team have brought joy and wonder to my life. Thank you.

[MatthewTheWanderer]

Actually discovering alien life would be easily one of the coolest things to ever happen!

[Jobobn]

1) Having a planet with a supercritical ocean would make for some pretty interesting chemistry and physics. For instance, if there's areas of the oceans near the critical point, tiny fluctuations in temperature would cause massive changes in density, which would create a massively turbulent zone. Additionally, the osmotic pressures would, if I'm not mistaken, equilibrate EXTREMELY rapidly, which could make cellular life extremely difficult.

2) I'm probably preaching to the choir here, but now that we've got a proof positive of the JWST's design, building another one should be radically cheaper than the original and its associated R&D. How about we cut 1% off our defense funding in the US for a single year, take that 18 billion dollars, and build+launch roughly 9 more of the things?

[allanburns]

I wake up every morning and check my phone to see if pbs space time has posted

[Zahlenteufel]

If I learned one thing on this channel it's that

✨it's never aliens until it's aliens ✨