[HN Gopher] Webb telescope helps refine Hubble constant
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Webb telescope helps refine Hubble constant
Author : pseudolus
Score : 85 points
Date : 2025-05-28 09:49 UTC (3 days ago)
(HTM) web link (phys.org)
(TXT) w3m dump (phys.org)
| redwood wrote:
| Amazing timing considering that Atlantic article that made the
| rounds here yesterday
| https://www.theatlantic.com/science/archive/2025/05/adam-rie...
| stogot wrote:
| I can't read the rest of the article, but is the JWT
| contradicting his conclusion?
| layer8 wrote:
| His thinking is based on the assumption that the Hubble
| tension can't be reconciled with the standard model.
|
| https://archive.ph/HuLlG
| r721 wrote:
| Discussion: https://news.ycombinator.com/item?id=44136945 (72
| comments)
| netcraft wrote:
| I've always thought as a layman that the weakest link in all of
| this is our cosmic distance ladder, seems like the most likely
| place that errors would stack up and lead us to some wrong
| conclusions. So may places for things to go wrong, we make a lot
| of assumptions about type 1a supernovas actually being a constant
| brightness, dust obscuring our view of them, plus all of the
| assumptions we've made about even measuring the distance between
| the ones we've measured. And its not like cosmologists havent
| acknowledged this, but I think a lot of the hubble tension might
| be solved once we figure out how to measure these distances more
| accurately.
| db48x wrote:
| The error bars on those distances have been shrinking for
| decades. Slow steady progress.
| bonzini wrote:
| ... And for completeness, the shrinking actually made the
| tension worse.
| jug wrote:
| Until now with a far better telescope able to significantly
| improve the sample size, that is.
|
| Ugh, this is so frustrating. We know our current theories
| cannot be complete but the LHC has mostly just confirmed
| assumptions, and now this. Everything seems to well
| contained.
| dvh wrote:
| Which is exactly how systematic error would manifest
| db48x wrote:
| It would have to be a pretty robust error to survive 30
| years of continuous study.
| sandworm101 wrote:
| The various candles are not independent yardsticks, nor are
| they just assumed to be true. Wherever possible they are
| compared against each other. And there are people who spend
| entire careers debating how dust absorbs light in order to best
| compensate for such things.
|
| If measurements point to some sort of incongruity, questioning
| the accuracy of one's ruler is a fools trap. Altering the
| rulers to remove incongruities results in a spiral of
| compromises, internal debates that don't result in progress. If
| one suspects that the rulers are wrong, the answer is to build
| a better ruler. Not to arbitrarily chop bits off until the
| difficult observations go away.
| netcraft wrote:
| I totally agree, hope my comment didnt come off to the
| contrary. As a layman, I consume most of my information
| through popsci sources (though I try to go more for the Dr.
| Beckys than the meatless or sensational stuff), and its
| generally described as something that we just take for
| granted - "we just found the oldest galaxy ever observed,
| only a few hundred million years after the big bang - and its
| too bright and has way more 'metals' than expected" - but we
| measured that with redshift, which makes a bunch of
| assumptions that of course they cant talk about in every
| video, but we dont talk about anyone questioning them.
|
| I have no doubt that there are great scientist spending their
| entire careers trying to improve these rulers and
| measurements, but I also know that there are great scientists
| spending their entire careers basing everything on the best
| rulers they have...
| makaking wrote:
| Webb was well worth the extended wait
| Workaccount2 wrote:
| This article is about another paper suggesting a resolution.
|
| It is not an article about a resolution having been confirmed.
| gammarator wrote:
| If you think scientific discoveries like this are important,
| _please_ contact your congressperson and indicate that you oppose
| the catastrophic cuts proposed to NASA astrophysics in the
| President's Budget Request: https://www.planetary.org/press-
| releases/the-planetary-socie...
| ghastmaster wrote:
| There are alternatives to taxation. With enough attention and
| disposable income, citizens can privately fund amazing things.
| Like the polio vaccine was.
|
| Alternatives: https://en.m.wikipedia.org/wiki/List_of_non-
| profit_space_age...
| jfengel wrote:
| You mean the polio vaccine distributed by the World Health
| Organization, and developed with the assistance of the New
| York Public Health Department?
| ghastmaster wrote:
| The Jonas Salk research and development of the first polio
| vaccine that saved many lives is what I am referring to.
| See quote and article below.
|
| >There was very little government funding for any kind of
| biomedical research. The polio research was privately
| funded through the March of Dimes," explained Randy Juhl,
| Dean Emeritus and Distinguished Service Professor Emeritus
| in the School of Pharmacy.
|
| https://www.pittwire.pitt.edu/pittwire/features-
| articles/ann...
| arrosenberg wrote:
| The same March of Dimes that was founded by Franklin
| Delano Roosevelt when he was President? Technically the
| money didn't come from government coffers, but it's very
| silly (and incorrect) to suggest that the effort was
| independent of the government.
| comicjk wrote:
| Regardless of what funding mechanism you would prefer in its
| place, turning off the existing system with no transition
| plan is a huge mistake.
| gizajob wrote:
| The problem is that this totally unmoves the layman, same as an
| incremental change in a metaphysical system would unmove the
| layman. Just one costs a lot more than the other.
| layer8 wrote:
| That's why you want to move the congressman.
| JumpCrisscross wrote:
| > _problem is that this totally unmoves the layman_
|
| Which is why we live in a republic. (And since the Industrial
| Revolution and Battle of Jena, one twinned to a technocratic
| administrative state.)
| jfengel wrote:
| I appreciate that, and science should be saved.
|
| But the cuts go far beyond that, to things that are less showy
| but with more direct effects on the lives of people. Tens of
| thousands of jobs have been lost, with microscopic effects on
| the bottom line, but with myriad small effects on our parks,
| our roads, even national security.
|
| Space is the "charismatic mega fauna" of the budget, but the
| whole "ecosystem" is ravaged. It must be saved, but take it as
| an indicator of just how much damage has been done. Spare a
| thought and a word for the NIH, the Fish and Wildlife Service,
| and the Social Security administrators whose jobs are not
| glamorous but nonetheless critical to people who depend on
| them.
| kulahan wrote:
| Does astroscience not deserve a spokesperson? We aren't
| allowed to be passionate about this if other things are "more
| important"?
|
| Those issues have their cheerleaders, so I see no reason to
| start with "that's good, BUT".
|
| I really hate this trend of pretending people are supposed to
| care about A more than B and that, more than C. Let people
| champion the things they're passionate about. Everyone is
| already suffering from compassion fatigue.
| JumpCrisscross wrote:
| > _Spare a thought and a word for the NIH, the Fish and
| Wildlife Service, and the Social Security administrators_
|
| Not sure framing this in terms of sympathy for jobless
| bureaucrats is as effective as considering the impact on
| babies who will die of diseases in cancelled pipelines,
| ecosystems and fisheries that will collapse due to negligence
| or proud grandmas who will go hungry because SSA fucked up
| their cheques.
| devwastaken wrote:
| NASA like all old orgs are extremely inefficient and
| overwhelmingly waste money. The solution is to create new orgs
| not hindered by old people that do the least work for the most
| pay.
| bandyaboot wrote:
| This has to be satire.
| JumpCrisscross wrote:
| > _NASA like all old orgs are extremely inefficient and
| overwhelmingly waste money_
|
| The U.S. government just got red teamed by an _extremely_
| adversarial auditor in DOGE. They weren't able to find almost
| _any_ fraud (outside the DoD, which they didn't touch). They
| found _maybe_ tens of billions of spending they didn't like
| out of a budget of trillions.
|
| Also, we're on a start-up board. Are you seriously arguing
| that every start-up, or even the median start-up, is less
| wasteful than the median century-old company?
| pfdietz wrote:
| NASA inefficiency is driven from the top down, by terrible
| goals and perverse incentives, mainly inflicted on the
| agency by lawmakers, but also due to getting stuck in a
| local optimum. It's not bottom up waste and fraud.
| JumpCrisscross wrote:
| > _NASA inefficiency is driven from the top down, by
| terrible goals and perverse incentives_
|
| To the extent there is documented inefficiency at NASA,
| it's in the way it manages its contractors for manned
| exploration. Its science budget is a paragon of
| institutional efficiency.
|
| > _It 's not bottom up waste and fraud_
|
| Read the GAO report [1]. (Ctrl + F Bechtel.)
|
| But for sake of argument, let's assume this is true. How
| does cutting the science budget while preserving SLS make
| sense?
|
| [1] https://www.gao.gov/products/gao-24-106256
| behringer wrote:
| So where's private businesses space telescope, if they're so
| efficient?
| kulahan wrote:
| Efficiency != profitability, though I don't agree with him
| either. Not sure there's much money to be made while
| searching the cosmos
| yibg wrote:
| Not in the short term and not directly for the company
| doing it. This is more of a reason for government funding
| though, not less.
| Larrikin wrote:
| Post your sources
| timewizard wrote:
| NASA did take a 25% budget cut. Through a combination of OMB
| and NASA decisions this led to a 50% cut in the entire sciences
| budget which went from $7.3b to $3.9b; however, the line item
| budgets for both Webb and Hubble are not touched and both are
| expected to operate at full planned capacity.
|
| The rest of the cuts are around propulsion systems and mars
| science missions. The administration and some parts of NASA see
| the commercial segment becoming more developed and more capable
| and are hoping they will be able to fill the gap. This also
| accelerates the plan to retire the ISS and move to commercial
| orbital platforms.
|
| Interestingly this budget does allocate $646 million more to
| exploration in 2025 than it did in 2024. Showing a shift in
| priorities from Earth based science missions to full manned
| missions returning to the Moon and eventually to Mars.
| w10-1 wrote:
| If your congressperson is Republican. Only their votes matter
| for the current budget.
| _joel wrote:
| Having waited half my life to see Webb finally launch, it's
| amazing to see how much we're discovering through it. Seems like
| every other day there's another insight found.
| try_the_bass wrote:
| > Freedman's latest calculation, which incorporates data from
| both the Hubble Telescope and the James Webb Space Telescope,
| finds a value of 70.4 kilometers per second per megaparsec, plus
| or minus 3%.
|
| > That brings her value into statistical agreement with recent
| measurements from the cosmic microwave background, which is 67.4,
| plus or minus 0.7%.
|
| Does it? As a lay person who can do basic arithmetic, this seems
| incorrect? Maybe there is some rounding or truncation, since I
| didn't check the source paper, or maybe I don't understand how
| confidence intervals work.
|
| `70.4 x 0.97 = 68.288` and `67.4 x 1.007 = 67.8718`
|
| These numbers are certainly close, but to my naive
| interpretation, the ranges don't overlap?
| xoxxala wrote:
| It looks like "statistical agreement" is doing a lot of work in
| that statement.
| jdhwosnhw wrote:
| Not really. You can calculate the statistical significance of
| the difference of these measurements, which I've done here:
| https://www.mycompiler.io/view/4LA310YXZHO
|
| For a null hypothesis of "their differences are consistent
| with zero", the p-value is 17%, equivalent to a 1.4 sigma
| difference. That's pretty far from a reasonable rejection
| criterion for the null hypothesis. I think most people would
| agree that that means these measurements are plausibly
| consistent.
| addaon wrote:
| > These numbers are certainly close, but to my naive
| interpretation, the ranges don't overlap?
|
| As is typical, the tolerances given are sigma values for an
| assumed normal distribution, not the width of a uniform
| distribution. The disagreement is less than five sigma, so (in
| the domain of physics) the disagreement is not considered
| significant enough to be a high-confidence indicator of new
| physics.
| trhway wrote:
| it is "c" divided by the age of Universe for pretty obvious
| reasons. Now we just have to precisely determine the age of the
| Universe :)
| mr_mitm wrote:
| Nothing about this is obvious. The age of the universe is
| related to the integral over the inverse Hubble parameter.
| The age of the universe is founded by measuring the Hubble
| constant among other things, not the other way round.
| epistasis wrote:
| > "Using its infrared detectors, we can see through dust that has
| historically plagued accurate measurement of distances, and we
| can measure with much greater accuracy the brightnesses of
| stars," added co-author Barry Madore, of the Carnegie Institution
| for Science.
|
| It's amazing just rich the electromagnetic spectrum is for
| analyzing the universe, from radio to X-rays, and how
| complementary the pictures are. Though we get visually pleasing
| pictures in the visible spectrum, most of the really
| intellectually pleasing stuff of the past century has been
| outside the visible range.
| binarymax wrote:
| I have a total n00b question. Why would this be a "constant"?
| Wouldn't different galaxies and different matter in the universe
| expand at different rates, and be an acceleration/deceleration,
| where one observation is the derivative or velocity of that one
| entity being observed?
| mr_mitm wrote:
| Hubble found that the recessional velocity of a galaxy is
| proportional to its distance. The proportionality constant is
| called the Hubble constant.
|
| It's a bit of a misnomer though, because it's only constant
| through space, not time. At the time of discovery it was
| assumed to be constant in time, too.
| binarymax wrote:
| Thanks that makes sense. Strange why pop science articles
| don't explain this critical point. I probably should have
| looked it up.
| puzzledobserver wrote:
| A natural follow-up to your question might be: "If everything
| is expanding, then wouldn't the ruler itself be expanding, so
| the expansion becomes unobservable?"
|
| I'm not a physicist, but from my understanding, the situation
| is a bit more complicated than the phrasing in your question
| suggests.
|
| Observation #1: The light from far-away galaxies is redshifted
| (spectral lines are a bit off from where we'd expect them to
| be). This suggests that these galaxies are moving away from us.
| The farther away the galaxy, the more it is redshifted. This
| suggests that the farther away the galaxy, the faster it is
| moving. Observations indicate that the recession speed is
| directly proportional to distance.
|
| This observation is consistent with general relativity, which
| suggests an expanding universe with homogeneous mass.
|
| But on a smaller scale, gravitational binding somehow takes
| over, and on even smaller scale, things like electromagnetic
| and nuclear interactions start having a greater impact, and
| that's why the Milky Way isn't itself expanding. For that
| matter, even Andromeda (0.8 Mpc) is too close to be affected by
| Hubble-style expansion, which only becomes observable at the
| multi-megaparsec scale.
| Fraterkes wrote:
| Dumb question: why did we need to see far-away galaxys moving
| away faster than near galaxies to conclude that the universe was
| expanding? Wouldn't just the fact that everything is moving away
| from us lead to the same conclusion?
| AStonesThrow wrote:
| That is not a fact; there are stars that are moving closer to
| us, and the Andromeda Galaxy is expected to "collide" with the
| Milky Way at some future point.
| kryptiskt wrote:
| If we see farther away galaxies moving away at the same speed
| as nearby galaxies that means that all the expansion of the
| universe happens between us and the nearby galaxies (since the
| farther away galaxies wouldn't be moving away from the nearby
| galaxies). So we would have some kind of local expansion of
| space around our galaxy. This is if we see a redshift in all
| directions, if we see a redshift in one direction and a
| blueshift in the opposite direction, that just means that our
| galaxy is moving relative to the observed galaxies (also, such
| a dipole can be seen in the microwave background).
| JumpCrisscross wrote:
| > _why did we need to see far-away galaxys moving away faster
| than near galaxies to conclude that the universe was expanding?
| Wouldn't just the fact that everything is moving away from us
| lead to the same conclusion?_
|
| Imagine inflating a balloon onto which you've painted dots. All
| the dots move apart. But the ones furthest apart move apart
| faster than those close together. This is how you know the dots
| aren't just moving in their local environment, the entire space
| is expanding (everywhere).
|
| (If you want a 1D representation, move your fingers apart at a
| constant rate. Consider how much further apart your pinky and
| index finger are compared with your middle and ring finger.
| That wouldn't happen if you just make a Spock hand.)
| gjm11 wrote:
| I don't know whether it's some HN auto-"fixing" thing in this
| case, but the title is garbled. At present it ends "suggesting
| resolution rate debate" but the original title is "... suggesting
| resolution to long-standing expansion rate debate". There is no
| "resolution rate debate", whatever that might be. The claim is
| that new data might help resolve a debate about the expansion
| rate of the universe.
| tomhow wrote:
| It wasn't the HN software, the submitter was just trying to fit
| the title into the character limit. I've edited it to just
| include the first part of the article's title, verbatim.
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