Sudden Future Singularity (SFS) as soon as 8.7 million years in the future?
No, not the kind of Singularity usually discussed here… I’m referring to the possibility of phantom energy-driven rips in the cosmos caused by accelerating expansion, or “sudden future singularities of pressure”. (Technically: “a momentary infinite peak in the tidal forces of the universe.”) A recent paper by Ghodsi & Hendri shows that cosmic microwave background, baryon acoustic oscillations (BAO), and type 1a supernovae data is consistent with the possibility of a sudden future singularity as soon as 8.7 million years from now.
“Cosmological tests of sudden future singularities”
http://arxiv.org/pdf/1201.6661v1.pdf
As I understand it, the authors are not saying that a SFS is likely 8.7 million years from now, just possible. This puts a dampener on the notion that the only plausible scenario of cosmological breakdown is Heat Death.
Here’s another paper that outlines other exotic cosmological singularities which have been under discussion in the cosmology community for the past decade, and the behavior of pointlike particles and strings as they approach such singularities.
I would not put much stock in these far-fetched models. We have no idea about the origins of the cosmological constant, though no shortage of preprints and papers purporting to clarify them. If you look through the arxiv long enough, you can find a paper predicting anything you want.
It’s suspicious that you offer a context-insensitive rebuttal that basically means “no matter what you post from arxiv, it doesn’t matter”. So we should ignore anything from arxiv that might be controversial or makes us uncomfortable, then?
Accelerating expansion was also controversial and made people uncomfortable when it was first presented. Now it’s well-supported. If it were 15 years ago, wouldn’t you be the same person criticizing a paper on accelerating expansion and saying “you can predict anything you want”?
Weigh the evidence and engage in the object-level, don’t summarily dismiss things. Dismissing things while ignoring the object-level is an indication of not trying.
The difference with 1998 is that dark energy was forced on us by observation. These papers are saying, what if dark energy is increasing as fast as possible. There’s no observation of increasing dark energy.
Also, as shminux says, there are a zillion theories of dark energy. I even have one of my own. :-)
Sure, that’s fine. So is the upshot that I should feel ashamed for even posting the link?
What annoyed me (and I was annoyed) is the utter hypotheticalness of phantom energy. That is a disputable point—as they point out, there are models in which fields with the properties of phantom energy pop up, it wasn’t invented solely for the purpose of ending the universe in finite time. You could counter that by saying, are those models physically motivated, or are they just exploring mathematical possibilities? Ultimately, I think “death by phantom energy” belongs on someone’s exhaustive lists of “possible causes of human extinction”, but it’s way down the list, and belongs in a the specific subcompartment of “possible cosmological causes of human extinction”, with an annotation that there’s no actual evidence that phantom energy exists.
Also, “end of the universe as soon as 8.7 million years from now” is like saying “end of the earth as soon as asteroid impact one week from now”—or whatever is the minimum possible time from Earth that an asteroid could be while still being currently undetected. (Except we know that there are asteroids, and we don’t know that there is phantom energy, so the analogy isn’t exact. So maybe it’s more like “end of Earth by expanding sphere of planet-killing von-Neumann replicators that’s not yet visible to astronomers, as soon as a few thousand years from now”.) Even if you decided to believe in phantom energy, you have no reason to expect the end in millions of years, rather than billions or trillions of years.
I would add one more thing—phantom energy may appear to be possible, only because we still don’t understand physics well enough. Further conceptual progress in quantum gravity, and further progress in making use of the deep clues in particle physics, will eventually get us to the point that there will be a rational consensus on something more than “standard model plus gravity”. At that time, the proliferation of theoretical ideas over the past 35 years (since the standard model was assembled) will be put into its proper perspective—it was an attempt to discover the next layer of truth by running in all possible directions. But there’s only one truth, and once we get to the next level, whether by progress in theory or progress in experiment, most of that speculation will only be of historical interest.
This helps clarify your reaction to me, thanks!
ArXiv is not a bastion of peer-reviewed science.
Ditto everything said below about comparing experimental evidence to theological physics.
Yes, but I never claimed that this was 100% certain, I’m just presenting it as food for thought. What’s up with these reactions here? I’m perplexed.
What’s up with the insinuation that this is “theological physics”? I don’t have a strong opinion on this paper either way, and I’m weirded out by the highly defensive reactions I’m getting to posting it. I’m interested in the new kinds of singularities being postulated here, that’s the main thing.
It considers a time scale so long that the possibility of it ever being empirically tested is vanishingly small.
There’s really no relevance to LW to be found here.
Downvoted for comparing hard experimental data on the expansion of the universe with cooked up models by people in need of grant money.
Downvoted for obfuscating whatever point you may have had about the difference between theoretical and experimental papers with petty insinuations about corruption by economic incentives.
Downvoted for telling people you’re downvoting, contributing to a trend within this thread of increased emphasis on semantics and insults.....(I’m not proud of what I’ve done here)
(If you can tell ahead of time that you are not proud of what you are about to do it is usually best to not do it.)
Downvoted because of a nice progression −4 ⇒ −3 ⇒ −2 ⇒ −1 ⇒ 0 (this!)
Voted away from 0 (currently downvoted) because I object to people downvoting me to make pretty patterns and so have a preference for their pattern preference at my expense not being satisfied.
Also: commented because if gRR does manage somehow to enforce his pattern preference it will ensure that I will be upvoted.
Upvoted to keep the justice and the pattern. (Will remove this soon)
No luck, the pattern’s shifted: it is currently −6 ⇒ −5 ⇒ −4 ⇒ −3 ⇒ −2 ⇒ −1 (parent) ⇒ 0 (this!)
Sounds good. I really didn’t like the comment which you place at −6!