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Frying Earth's nearest exoplanet + Boltzmann brain existing more probable than cosmos

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Massive stellar flare may have fried Earth’s nearest exoplanet

EXCERPT: Proxima Centauri has a temper. Earth’s nearest planet-hosting neighbor released a gigantic flare in March 2017, a new analysis of observations of the star shows. And that’s bad news for the potential for life on the star’s planet, Proxima b. The star got 1,000 times brighter over 10 seconds before dimming again. That can best be explained by an enormous stellar flare, astronomer Meredith MacGregor of the Carnegie Institution for Science in Washington, D.C., and colleagues report February 26 in Astrophysical Journal Letters. Because Proxima b is so much closer to its star than Earth is to the sun, the flare would have blasted Proxima b with 4,000 times more radiation than Earth typically gets from the sun’s flares. “If there are flares like this at all frequently, then [the exoplanet] is likely not in the best shape,” MacGregor says....


A Boltzmann brain existing is more probable than our universe existing

EXCERPT: Can you trust the world to be consistent? Scientists don’t have much choice. They need to assume that objective observations of the universe can be trusted. [...] “The problem arises when we start with our experience of the world, use it to construct our best theory of how the world actually operates, and then realize that this theory itself predicts that our sense data are completely unreliable,” writes Sean Carroll, a Caltech theoretical physicist, in a paper published last year. He went with the title “Why Boltzmann Brains Are Bad” because the theories that predict them are, as a result, “cognitively unstable: they cannot simultaneously be true and justifiably believed.” They lead us to think that the universe could simply be our mind thinking it is part of a vast cosmos.

[...] Although it’s an interesting paradox, most astrophysicists don’t think Boltzmann brains are a real possibility. (Carroll, for instance, mercilessly deems them “self-undermining and unworthy of serious consideration,” on account of their cognitive instability.) Instead they look to physical processes that would solve the paradox. The physical processes that give rise to the Boltzmann brain possibility are the vacuum energy fluctuations intrinsic to quantum theory—small energy fluctuations can appear out of the vacuum. [...] These fluctuations were in thermal equilibrium in the early universe, so they follow the same random Boltzmann statistics as the primordial cosmos, making them also more likely to give rise to a Boltzmann brain rather than the universe we seem to be in.

But it turns out that, since the universe is expanding, these apparent fluctuations might not be coming from the vacuum. Instead, as the universe expands, the edge of the observable universe causes thermal fluctuations to appear, much like the event horizon of a black hole gives rise to Hawking radiation. This gives the appearance of vacuum fluctuations, from our point of view. The true vacuum of space and time isn’t fluctuating, so it cannot create a Boltzmann brain....


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