Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Evidence that the key assumption made in discovery of dark energy is in error

phys.org

Post reply on HN
Print view View original

11–20 of 295 posts

Re: Evidence that the key assumption made in discovery of dark energy is in error

#11

Post by phkahler »

jshevek wrote: post #2

"...Prof. Young-Wook Lee (Yonsei Univ., Seoul), who led the project said, "Quoting Carl Sagan, extraordinary claims require extraordinary evidence, but I am not sure we have such extraordinary evidence for dark energy. Our result illustrates that dark energy from SN cosmology, which led to the 2011 Nobel Prize in Physics, might be an artifact of a fragile and false assumption."" Is he implying that other cosmologists…

>> Is he implying that other cosmologists have proceeded as if dark energy is well evidenced?

As a non-cosmologist just reading HN I would say yes. Not quite as extensively as Dark matter though. I personally think that's a mistake too based on my limited research on the topic. If these are both overturned it will be a huge blow to "scientists" credibility in the eyes of the public. That's how invested they are.

Re: Evidence that the key assumption made in discovery of dark energy is in error

#12

Post by coliveira »

phkahler wrote: post #11
jshevek wrote: post #2

"...Prof. Young-Wook Lee (Yonsei Univ., Seoul), who led the project said, "Quoting Carl Sagan, extraordinary claims require extraordinary evidence, but I am not sure we have such extraordinary evidence for dark energy. Our result illustrates that dark energy from SN cosmology, which led to the 2011 Nobel Prize in Physics, might be an artifact of a fragile and false assumption."" Is he implying that other cosmologists…

>> Is he implying that other cosmologists have proceeded as if dark energy is well evidenced? As a non-cosmologist just reading HN I would say yes. Not quite as extensively as Dark matter though. I personally think that's a mistake too based on my limited research on the topic. If these are both overturned it will be a huge blow to "scientists" credibility in the eyes of the public. That's how invested they are.

> If these are both overturned it will be a huge blow to "scientists" credibility

This is nonsense. Scientists have been wrong in several occasions, it is just part of the profession. For example, in the years leading to the discovery of relativity, many physicists believed there was something called "ether" that worked to fix the speed of light that they had evidence to be the same in all directions.

Re: Evidence that the key assumption made in discovery of dark energy is in error

#13

Post by dfischer »

jshevek wrote: post #2

"...Prof. Young-Wook Lee (Yonsei Univ., Seoul), who led the project said, "Quoting Carl Sagan, extraordinary claims require extraordinary evidence, but I am not sure we have such extraordinary evidence for dark energy. Our result illustrates that dark energy from SN cosmology, which led to the 2011 Nobel Prize in Physics, might be an artifact of a fragile and false assumption."" Is he implying that other cosmologists…

As a frequent listener of cosmologists I'd say they regularly frame answers as dark energy were true.

Re: Evidence that the key assumption made in discovery of dark energy is in error

#14

Post by [deleted] »

coliveira wrote: post #12
phkahler wrote: post #11

Earlier quoted context omitted.

>> Is he implying that other cosmologists have proceeded as if dark energy is well evidenced? As a non-cosmologist just reading HN I would say yes. Not quite as extensively as Dark matter though. I personally think that's a mistake too based on my limited research on the topic. If these are both overturned it will be a huge blow to "scientists" credibility in the eyes of the public. That's how invested they are.

> If these are both overturned it will be a huge blow to "scientists" credibility This is nonsense. Scientists have been wrong in several occasions, it is just part of the profession. For example, in the years leading to the discovery of relativity, many physicists believed there was something called "ether" that worked to fix the speed of light that they had evidence to be the same in all directions.

[deleted]

Re: Evidence that the key assumption made in discovery of dark energy is in error

#15

Post by marcosdumay »

6nf wrote: post #9
gbrown wrote: post #6

Earlier quoted context omitted.

I thought there was little reason to expect a big rip, because it requires assumptions about an increasing cosmological constant, which there’s no evidence for.

What do you mean? There's lots of evidence that the expansion of the universe is accelerating and that's the whole reason we believe that dark energy exists. Most cosmologists do believe we're heading for a big rip.

The existence of a cosmological constant is different from it's ever increasing value.

The evidences for the later are non-existent.

Re: Evidence that the key assumption made in discovery of dark energy is in error

#16

Post by mirimir »

6nf wrote: post #9
gbrown wrote: post #6

Earlier quoted context omitted.

I thought there was little reason to expect a big rip, because it requires assumptions about an increasing cosmological constant, which there’s no evidence for.

What do you mean? There's lots of evidence that the expansion of the universe is accelerating and that's the whole reason we believe that dark energy exists. Most cosmologists do believe we're heading for a big rip.

According to TFA, it's the "most direct and strongest evidence for the accelerating universe" that's now possibly an artifact. As I understand it, "dark energy" is fundamentally just another way to say "accelerating expansion".

Re: Evidence that the key assumption made in discovery of dark energy is in error

#18

Post by crazygringo »

Do I understand correctly that this is actually saying that accelerating expansion of the universe may be in error? That there is, instead, no accelerating at all, but merely constant expansion?

Or can there still be acceleration without dark energy? I'm unclear if they are essentially the same hypothesis or if there are more complicated subtleties I'm missing.

Re: Evidence that the key assumption made in discovery of dark energy is in error

#19

Post by tomrod »

sparker72678 wrote: post #3

> Taken at face values, the luminosity evolution of SN is significant enough to question the very existence of dark energy. When the luminosity evolution of SN is properly taken into account, the team found that the evidence for the existence of dark energy simply goes away Cosmology is great because there's still so much in flux. There are so many fundamental things that are still in active research. I find it all v…

My exact thought was "Yaye for science!" I love that science has self-correction built into its core.

Re: Evidence that the key assumption made in discovery of dark energy is in error

#20

Post by philipov »

crazygringo wrote: post #18

Do I understand correctly that this is actually saying that accelerating expansion of the universe may be in error? That there is, instead, no accelerating at all, but merely constant expansion? Or can there still be acceleration without dark energy? I'm unclear if they are essentially the same hypothesis or if there are more complicated subtleties I'm missing.

There are very few ways to modify Einstein's Equations and still have them make sense. An easy one is to add a constant term. Such a term is known as the Cosmological Constant, and a positive value for it would result in a constant repulsive force between masses regardless of distance. This results in an accelerating expansion of the entire universe, but, with a supremely small value it only becomes noticeable at large scales, where it starts to dominate attractive gravity. This appears to model what we're observed happening with galaxy clusters.

Dark Energy is a hypothesis for explaining why such a very small cosmological constant might exist, suggesting that the universe is permeated with a constant negative energy field. However, the article refers to observational evidence measuring the expansion of the universe, not dark energy. There is no evidence for dark energy as such, and if you listen to colloquia on cosmology, you will hear about the cosmological constant, not dark energy. It is not necessary to hypothesize the existence of negative energy particles to model what we've observed, and you'll only really hear the term used in the popular press because it sounds sexy.

Post reply on HN