4 ms·

The universe is expanding faster and is younger than we thought

64 points by pzs 7y ago

everdev 7y ago
> Using that 74 figure means the universe is somewhere between 12.5 billion and 13 billion years old. That’s much younger than the established estimates of 13.6 billion to 13.8 billion. If true, would that mean that the observable universe is smaller than we thought? And that the distances to distant galaxies might be off as well?
- irjustin 7y ago
  Wow great question, I'm just as confused. I imagine because the absolute distance is still the same, but how quickly it got to that position is what's unknown. The confusion I have is how much is redshift used to determine the distance of the galaxy vs using standard candle extrapolation?
- zahrc 7y ago
  From what I understand it’s size is the same as estimated before. Basically it just took less time, to reach its current size.
- thedaemon 7y ago
  It's just relative.
acqq 7y ago
The paper: https://arxiv.org/abs/1903.07603 https://arxiv.org/abs/1903.07603 The disagreement existed for years already, the news is one more value from those measurements using the "distance ladder" which disagrees with the values obtained from "CMB and BAO" method. Both groups believe they haven't made any error in their measurements and can still claim so: https://www.forbes.com/sites/startswithabang/2019/05/03/cosmologys-biggest-conundrum-is-a-clue-not-a-controversy/ https://www.forbes.com/sites/startswithabang/2019/05/03/cosm...
- mirimir 7y ago
  OK, so these are basically expansion rates measured for different times, right? And so they're not expected to be the same. But what's problematic is disagreement with models for how the expansion rate changed over time. Yes?
  - acqq 7y ago
    > And so they're not expected to be the same. Still there was a kind of hope that there would be just one Hubble constant eventually, resulting from both measurements, that some kind of unexpected error would be discovered on one (or both) of the sides. But what's happening is illustrated on the picture subtitled "Modern measurement tensions..." in the second link, plus the newest result from the Riess' paper: "74.03 +/- 1.42 km/s/Mpc" with "an uncertainty of 1.91%" which you should imagine appearing to the right of the picture, with the dot at 74 and much narrower red bar. So, looking at that picture again, we have the "blue" and the "red" results for years already that don't converge and keep doing so, although both approaches use always more advanced techniques. But, quoting from the second link: "It is possible that the ways we measure the expansion rate of the Universe are actually revealing something novel about the nature of the Universe itself. Something about the Universe could be changing with time" "Some options include: - our local region of the Universe has unusual properties compared to the average (which is already disfavored), - dark energy is changing in an unexpected fashion over time, - gravity behaves differently than we've anticipated on cosmic scales, - or there is a new type of field or force permeating the Universe." "The option of evolving dark energy is of particular interest and importance, as this is exactly what NASA's future flagship mission for astrophysics, WFIRST, is being explicitly designed to measure." But also: https://en.wikipedia.org/wiki/Wide_Field_Infrared_Survey_Telescope https://en.wikipedia.org/wiki/Wide_Field_Infrared_Survey_Tel... "The Trump administration's proposed FY2019 budget would terminate WFIRST" "Again the Trump administration proposed to terminate WFIRST in its FY2020 budget proposal to Congress" And finally, from the OP article: "Distinguished University of Chicago astrophysicist Wendy Freedman" "spent five years looking at different stars than Riess to come up with a third calculation of the expansion rate. They just submitted their work to the same journal. Freedman wouldn’t reveal her number but said it is between the two other figures."
AstralStorm 7y ago
One day both methods will be looked upon just as the Ptolemeian model of the solar system is now. Great fit, incorrect model.
syllable_studio 7y ago
What if the universe isn't expanding, but rather we're contracting?
- dpark 7y ago
  And the laws of physics are continuously changing with our contraction such that it’s indistinguishable from the universe expanding? In that case, there is no difference, so reframing it in term of local contraction is meaningless. See also: http://www.rogermwilcox.com/darksucker.html http://www.rogermwilcox.com/darksucker.html

64 points by pzs 7y ago

> Using that 74 figure means the universe is somewhere between 12.5 billion and 13 billion years old. That’s much younger than the established estimates of 13.6 billion to 13.8 billion. If true, would that mean that the observable universe is smaller than we thought? And that the distances to distant galaxies might be off as well?

irjustin 7y ago
Wow great question, I'm just as confused. I imagine because the absolute distance is still the same, but how quickly it got to that position is what's unknown. The confusion I have is how much is redshift used to determine the distance of the galaxy vs using standard candle extrapolation?
zahrc 7y ago
From what I understand it’s size is the same as estimated before. Basically it just took less time, to reach its current size.
thedaemon 7y ago
It's just relative.

acqq 7y ago

The paper: https://arxiv.org/abs/1903.07603 https://arxiv.org/abs/1903.07603 The disagreement existed for years already, the news is one more value from those measurements using the "distance ladder" which disagrees with the values obtained from "CMB and BAO" method. Both groups believe they haven't made any error in their measurements and can still claim so: https://www.forbes.com/sites/startswithabang/2019/05/03/cosmologys-biggest-conundrum-is-a-clue-not-a-controversy/ https://www.forbes.com/sites/startswithabang/2019/05/03/cosm...

mirimir 7y ago
OK, so these are basically expansion rates measured for different times, right? And so they're not expected to be the same. But what's problematic is disagreement with models for how the expansion rate changed over time. Yes?
- acqq 7y ago
  > And so they're not expected to be the same. Still there was a kind of hope that there would be just one Hubble constant eventually, resulting from both measurements, that some kind of unexpected error would be discovered on one (or both) of the sides. But what's happening is illustrated on the picture subtitled "Modern measurement tensions..." in the second link, plus the newest result from the Riess' paper: "74.03 +/- 1.42 km/s/Mpc" with "an uncertainty of 1.91%" which you should imagine appearing to the right of the picture, with the dot at 74 and much narrower red bar. So, looking at that picture again, we have the "blue" and the "red" results for years already that don't converge and keep doing so, although both approaches use always more advanced techniques. But, quoting from the second link: "It is possible that the ways we measure the expansion rate of the Universe are actually revealing something novel about the nature of the Universe itself. Something about the Universe could be changing with time" "Some options include: - our local region of the Universe has unusual properties compared to the average (which is already disfavored), - dark energy is changing in an unexpected fashion over time, - gravity behaves differently than we've anticipated on cosmic scales, - or there is a new type of field or force permeating the Universe." "The option of evolving dark energy is of particular interest and importance, as this is exactly what NASA's future flagship mission for astrophysics, WFIRST, is being explicitly designed to measure." But also: https://en.wikipedia.org/wiki/Wide_Field_Infrared_Survey_Telescope https://en.wikipedia.org/wiki/Wide_Field_Infrared_Survey_Tel... "The Trump administration's proposed FY2019 budget would terminate WFIRST" "Again the Trump administration proposed to terminate WFIRST in its FY2020 budget proposal to Congress" And finally, from the OP article: "Distinguished University of Chicago astrophysicist Wendy Freedman" "spent five years looking at different stars than Riess to come up with a third calculation of the expansion rate. They just submitted their work to the same journal. Freedman wouldn’t reveal her number but said it is between the two other figures."

AstralStorm 7y ago

One day both methods will be looked upon just as the Ptolemeian model of the solar system is now. Great fit, incorrect model.

syllable_studio 7y ago

What if the universe isn't expanding, but rather we're contracting?

dpark 7y ago
And the laws of physics are continuously changing with our contraction such that it’s indistinguishable from the universe expanding? In that case, there is no difference, so reframing it in term of local contraction is meaningless. See also: http://www.rogermwilcox.com/darksucker.html http://www.rogermwilcox.com/darksucker.html