Yesterday 08:55 PM
Can our model of the cosmos work without dark energy? New research says it can
https://gizmodo.com/can-our-model-of-the...2000765968
INTRO: In a new paper published last week in Proceedings of the Royal Society A, though, a team of researchers demonstrate how the problem of accelerated expansion might be more a matter of current cosmological models being based on instabilities that do not translate very well into observable reality.
“Unstable solutions in physics and science are considered not physical,” Blake Temple, the study’s co-author and a mathematician at University of California, Davis (UC Davis), said in a statement. “You’ll never observe them in nature.” (MORE - details)
Astrobiology's looming statistical crisis
https://www.universetoday.com/articles/a...cal-crisis
EXCERPT: In Bayesian statistics, the kind used by most astronomers, when you don’t know the likelihood of something happening, you use what’s called a “diffuse prior”. Essentially, you tell the math - I have no idea how common life is, and I also have no idea how likely this signal is being generated by some process that I don’t understand is non-biological in nature. The problem, as Dr. Kipping shows in his paper, is that when you do that, the math gets quickly out of control.
In order to reach a Bayesian factor of 10 (meaning the evidence for life is 10 times stronger than the evidence for no life), the number of planets to be surveyed ranges from a mere 12,366 to a whopping 44 trillion. Keep in mind that these planets have to all have the same signature being analyzed - that’s how the statistics works. Also keep in mind that, as of the time of writing, we have only found around 6,200 confirmed exoplanets. In other words, we would need to double our total stock of confirmed exoplanets, and all of those exoplanets would have to have the exact same signal of potential biosignatures in order to meet the actual statistical requirements of definitively detecting life.
To put it bluntly - that’s not going to happen any time soon. And Dr. Kipping makes that point in the paper. Though he does offer a solution that sounds like it’s stolen straight from Silicon Valley’s playbook - A/B testing. To do this for exoplanet analysis, he suggests splitting a group of exoplanets with the same potentially interesting signal into two groups, but with a key feature - both groups have to have the same false positive rate. That would mean that, mathematically at least, that “unknown confounder” would cancel out, making the comparison between the two groups more direct at least.
Fraser discusses the possibility of finding certain molecules that stand out as biosignatures, and what other processes might create them.
While the math behind that is elegant, it faces a huge hurdle in reality - how do you find two groups of planets where “life” behaves differently but the unknown chemistry that could be driving the signals we’re interpreting as life behaves exactly the same across all planets.
To put it bluntly, the likelihood of that happening is almost as remote as us finding 44 trillion exoplanets in the next 25 years. So, it appears that the 25 exoplanets that the Habitable Worlds Observatory plans to survey when it is launched next year is only a drop in the statistical bucket of what data we would need to collect to prove life definitively exists on another planet... (MORE - missing details)
https://gizmodo.com/can-our-model-of-the...2000765968
INTRO: In a new paper published last week in Proceedings of the Royal Society A, though, a team of researchers demonstrate how the problem of accelerated expansion might be more a matter of current cosmological models being based on instabilities that do not translate very well into observable reality.
“Unstable solutions in physics and science are considered not physical,” Blake Temple, the study’s co-author and a mathematician at University of California, Davis (UC Davis), said in a statement. “You’ll never observe them in nature.” (MORE - details)
Astrobiology's looming statistical crisis
https://www.universetoday.com/articles/a...cal-crisis
EXCERPT: In Bayesian statistics, the kind used by most astronomers, when you don’t know the likelihood of something happening, you use what’s called a “diffuse prior”. Essentially, you tell the math - I have no idea how common life is, and I also have no idea how likely this signal is being generated by some process that I don’t understand is non-biological in nature. The problem, as Dr. Kipping shows in his paper, is that when you do that, the math gets quickly out of control.
In order to reach a Bayesian factor of 10 (meaning the evidence for life is 10 times stronger than the evidence for no life), the number of planets to be surveyed ranges from a mere 12,366 to a whopping 44 trillion. Keep in mind that these planets have to all have the same signature being analyzed - that’s how the statistics works. Also keep in mind that, as of the time of writing, we have only found around 6,200 confirmed exoplanets. In other words, we would need to double our total stock of confirmed exoplanets, and all of those exoplanets would have to have the exact same signal of potential biosignatures in order to meet the actual statistical requirements of definitively detecting life.
To put it bluntly - that’s not going to happen any time soon. And Dr. Kipping makes that point in the paper. Though he does offer a solution that sounds like it’s stolen straight from Silicon Valley’s playbook - A/B testing. To do this for exoplanet analysis, he suggests splitting a group of exoplanets with the same potentially interesting signal into two groups, but with a key feature - both groups have to have the same false positive rate. That would mean that, mathematically at least, that “unknown confounder” would cancel out, making the comparison between the two groups more direct at least.
Fraser discusses the possibility of finding certain molecules that stand out as biosignatures, and what other processes might create them.
While the math behind that is elegant, it faces a huge hurdle in reality - how do you find two groups of planets where “life” behaves differently but the unknown chemistry that could be driving the signals we’re interpreting as life behaves exactly the same across all planets.
To put it bluntly, the likelihood of that happening is almost as remote as us finding 44 trillion exoplanets in the next 25 years. So, it appears that the 25 exoplanets that the Habitable Worlds Observatory plans to survey when it is launched next year is only a drop in the statistical bucket of what data we would need to collect to prove life definitively exists on another planet... (MORE - missing details)