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TL;DR: the Big Rip is likely not to be the fate of the Universe as dark energy term in lambda-CDM cosmology is not a constant but weakens as time moves forward.

TL;DR: the Big Rip is likely not to be the fate of the Universe as dark energy term in lambda-CDM cosmology is not a constant but weakens as time moves forward. Seems like Heat Death or Big Crunch options are back on the menu!

codeulike 2y ago
Thanks. You'd think they'd end the article with a summary. Somewhere in that load of words they've managed to bury the new fate of the universe.
- digging 2y ago
  The article does end with a summary.
deleted 2y ago
[deleted]
digging 2y ago
I think your summary misses the mark. The Big Rip was not the most likely outcome before this new evidence. Heat Death has been the expectation/assumption. TL;DR of TFA: New evidence shows that dark energy may be weakening over time instead of staying constant, which could lead to a Big Crunch. We're eagerly awaiting further evidence.
boole1854 2y ago
I think that's a slightly incorrect TL;DR. Here's an updated version based on my reading: TL;DR: a heat death (Big Freeze) due to eternal acceleration was the previously favored candidate for the fate of the universe; but there's now evidence that dark energy varies, so acceleration may not be eternal; we may still get a Big Freeze (if it stop varying soon) or we may get a Big Crunch (if it keeps going far enough in the direction it has been going) or we may get a Big Rip (if it starts going in the opposite direction that it has been going)
mr_mitm 2y ago
You seem to have mixed up your scenarios. In the standard model, i.e. constant dark energy, the universe ends in heat death. Big Crunch or Big Rip were never off the menu in the sense that our measurements couldn't exclude a value of w!=-1. But it's a critical value, you'll never be able to exclude the other scenarios if it's truly -1, because you always have a positive measurement uncertainty. The standard model is the standard model because it fits the data best. This can change as measurements become more precise. Now new data hints at the standard model being incorrect (to the surprise of basically no one in cosmology), making a big crunch more likely, but still not strongly ruling out the other scenarios.

codeulike 2y ago

Thanks. You'd think they'd end the article with a summary. Somewhere in that load of words they've managed to bury the new fate of the universe.

digging 2y ago
The article does end with a summary.

deleted 2y ago

[deleted]

digging 2y ago

I think your summary misses the mark. The Big Rip was not the most likely outcome before this new evidence. Heat Death has been the expectation/assumption. TL;DR of TFA: New evidence shows that dark energy may be weakening over time instead of staying constant, which could lead to a Big Crunch. We're eagerly awaiting further evidence.

boole1854 2y ago

I think that's a slightly incorrect TL;DR. Here's an updated version based on my reading: TL;DR: a heat death (Big Freeze) due to eternal acceleration was the previously favored candidate for the fate of the universe; but there's now evidence that dark energy varies, so acceleration may not be eternal; we may still get a Big Freeze (if it stop varying soon) or we may get a Big Crunch (if it keeps going far enough in the direction it has been going) or we may get a Big Rip (if it starts going in the opposite direction that it has been going)

mr_mitm 2y ago

You seem to have mixed up your scenarios. In the standard model, i.e. constant dark energy, the universe ends in heat death. Big Crunch or Big Rip were never off the menu in the sense that our measurements couldn't exclude a value of w!=-1. But it's a critical value, you'll never be able to exclude the other scenarios if it's truly -1, because you always have a positive measurement uncertainty. The standard model is the standard model because it fits the data best. This can change as measurements become more precise. Now new data hints at the standard model being incorrect (to the surprise of basically no one in cosmology), making a big crunch more likely, but still not strongly ruling out the other scenarios.