Sigma is basically a representation of certainty that your result isn’t a statistical fluke. It comes from standard deviation in statistics but 1 sigma is 68% certain. 2 sigma is 95%. 3 sigma is 99.7%.
By convention, astronomy uses 3 sigma for “significance,” meaning you almost definitely found something. Particle physics, since it’s usually done in controlled experiments, usually requires 5 sigma (99.99994%).
It’s similar to margin of error in political polls.
By saying 1 sigma, they are basically saying tgat are 68% confident in the results. As you increase the sigma, your confidence in the results increases. Here is a site that goes into more in depth explanation:
https://news.mit.edu/2012/explained-sigma-0209#
It’s a number that statistically represents how strong the result is in the data basically. As far as I understand it, with astronomy the typical sigma value expected is 3
A chemical only produced by life on earth. But can it be produced by abiotic conditions on other planets? I’m not sure that has been ruled out at this point.
Yeah, this headline is bullshit. It's indication of possible life, but it isn't what the headline makes it sound. There's always other possible methods, even if we aren't aware of them yet. It's interesting, but doesn't confirm anything yet.
Even if Webb were to basically spot earth 2 5 light years away, I’d caution about getting excited for a radio chat.
Remember that life has existed on earth for something like 3 billion years, but multicellular life has only been around for 500 million or so years, humans in various forms have been around for about a million years, and we’ve only had radio for about a hundred years.
The vast majority of life that has ever existed on our planet has been single called organisms. Finding evidence of any life on another planet is huge news, but we should temper our expectations.
It’s way, way more likely for alien planets to have oceans full of plankton analogues as the dominant life. Considering the rest of this planet’s atmosphere is composed mostly of hydrogen, even their plankton would be weird by our standards.
It's a planet 8x the mass of the earth with a heavy hydrogen atmosphere and is considered very hot, the water is in a super critical state. I think if we found anything it would just be bacterial life.
My bet is on "previously unknown chemistry" creating the chemicals we found. It's never aliens :(