Webb telescope helps refine Hubble constant

> 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.

It looks like "statistical agreement" is doing a lot of work in that statement.

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 :)

The error bars on those distances have been shrinking for decades. Slow steady progress.

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.

Discussion: https://news.ycombinator.com/item?id=44136945 (72 comments)

I can’t read the rest of the article, but is the JWT contradicting his conclusion?

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.

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.

> 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.)

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).

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.

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.

If your congressperson is Republican. Only their votes matter for the current budget.

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.

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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.

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...

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.

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.