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Webb telescope helps refine Hubble constant
- redwood 1y agoAmazing timing considering that Atlantic article that made the rounds here yesterday https://www.theatlantic.com/science/archive/2025/05/adam-riess-hubble-tension/682980/ https://www.theatlantic.com/science/archive/2025/05/adam-rie...
- stogot 1y agoI can’t read the rest of the article, but is the JWT contradicting his conclusion?
- layer8 1y agoHis thinking is based on the assumption that the Hubble tension can't be reconciled with the standard model. https://archive.ph/HuLlG https://archive.ph/HuLlG
- r721 1y agoDiscussion: https://news.ycombinator.com/item?id=44136945 https://news.ycombinator.com/item?id=44136945 (72 comments)
- netcraft 1y agoI'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 1y agoThe error bars on those distances have been shrinking for decades. Slow steady progress.
- bonzini 1y ago... And for completeness, the shrinking actually made the tension worse.
- jug 1y agoUntil 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.
- deleted 1y ago[deleted]
- dvh 1y agoWhich is exactly how systematic error would manifest
- db48x 1y agoIt would have to be a pretty robust error to survive 30 years of continuous study.
- hnaccount_rng 1y agoOr a common unchallenged assumption. Orthodox errors are always only obvious in hindsight
- sandworm101 1y agoThe 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.
- ashoeafoot 1y ago[flagged]
- deleted 1y ago[deleted]
- makaking 1y agoWebb was well worth the extended wait
- Workaccount2 1y agoThis article is about another paper suggesting a resolution. It is not an article about a resolution having been confirmed.
- gammarator 1y agoIf 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-society-reissues-urgent-call-to-reject-disastrous-budget-proposal-for-nasa https://www.planetary.org/press-releases/the-planetary-socie...
- ghastmaster 1y agoThere 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_agencies https://en.m.wikipedia.org/wiki/List_of_non-profit_space_age...
- jfengel 1y agoYou mean the polio vaccine distributed by the World Health Organization, and developed with the assistance of the New York Public Health Department?
- ghastmaster 1y agoThe 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/anniversary-salk-team-s-polio-vaccine-source-hope-covid-19 https://www.pittwire.pitt.edu/pittwire/features-articles/ann...
- arrosenberg 1y agoThe 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.
- _joel 1y agoHaving 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 1y ago> 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 × 0.97 = 68.288` and `67.4 × 1.007 = 67.8718` These numbers are certainly close, but to my naive interpretation, the ranges don't overlap?
- xoxxala 1y agoIt looks like "statistical agreement" is doing a lot of work in that statement.
- jdhwosnhw 1y agoNot really. You can calculate the statistical significance of the difference of these measurements, which I’ve done here: https://www.mycompiler.io/view/4LA310YXZHO 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 1y ago> 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.
- suzzer99 1y agoThis wins some kind of award for most useful information packed into two sentences on HN. This is exactly what I've been wondering since this came out.
- epistasis 1y ago> "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 1y agoI 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 1y agoHubble 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 1y agoThanks that makes sense. Strange why pop science articles don’t explain this critical point. I probably should have looked it up.
- hnaccount_rng 1y agoThe irony of course being that Hubble's original data is, at least in modern scientific analysis, very well compatible with "no expansion". There is _a lot_ of community flavour involved in how we talk about measurement results
- puzzledobserver 1y agoA 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 1y agoDumb 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 1y agoThat 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 1y agoIf 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 1y ago> 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 1y agoI 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 1y agoIt 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.
- bawana 1y agoFurther away galaxies are receding faster. Light from further away galaxies is older. Does it therefore not follow that the expansion of the universe is slowing down?