Adam Riess and the Hubble tension | Hacker News Reader

Adam Riess and the Hubble tension

theatlantic.com

102 pointssamizdis75 comments

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Archive link using a tool I built to automatically redirect to archive links :)

https://unbloq.us/https://www.theatlantic.com/science/archiv...

archive.is already has a redirector btw:

https://archive.is/timegate/https://www.theatlantic.com/scie...

Wow this is really great

Thank you! Glad people are finding it useful :)

Archive link: https://archive.is/51R4k

Reminded me of this thread from a couple of days ago. Interesting that both Riess and Gough argue there's a sociological phenomenon amongst cosmologists. Though who knows what Riess might think of the "blowtorch theory." https://news.ycombinator.com/item?id=44115973

I have a phd in astronomy and I spent some time reading it yesterday. I don't think he'd think much of it. The theory seems to be aimed at explaining the existence of cosmic voids and the structure of the cosmic web. But these are pretty naturally explained by lambda CDM. And if the goal is to explain away dark matter, there are other pieces of evidence for dark matter that wouldn't be explained by this theory. At any rate, as far as I can tell it's not a quantitative theory so it would be hard to tie it to observations.

Interesting thanks!

Every scientist knows there is a sociological component to the practice of science. This is not a novel or noteworthy observation and I don’t think Riess was intending it to be.

Also, every cosmologist knows the standard model is not the final answer. I think the author is really trying to overstate the controversy.

But many non-cosmologists like me aren’t so aware. Many of us learned basic physics where the standard model is treated as a given. Or the standard if you don’t mind dad jokes.

I happen to not be a scientist but found the observation interesting given the overlapping subject matter. Especially given the stark differences in training/background. E.g. scientist/not scientist.

> For nearly a century, astronomers have known that the universe is expanding, because the galaxies that we can see around us through telescopes are all rushing away. Riess studied how they moved. He very carefully measured the distance of each one from Earth, and when all the data came together, in 1998, the results surprised him. They were “shocking even,” he told his colleagues in a flustered email that he sent on the eve of his honeymoon. A striking relationship had emerged: The farther away that galaxies were, the faster they were receding. This “immediately suggested a profound conclusion,” he said in his Nobel Prize lecture. Something is causing the expansion of the universe to accelerate.

I'm quite confused by this early paragraph. It seems to be claiming that Hubble's law was discovered in 1998 by Adam Riess, instead of in the 1920s by Edwin Hubble (and others).

It's the second derivative.

Riess et al's findings showed that galaxies farther away are not just receding faster (as Hubble's Law already described), but that the rate of expansion itself is increasing over time. This discovery suggested the presence of a mysterious force, now called dark energy, driving this acceleration.

This was unexpected because most astronomers at the time thought the expansion should be slowing down due to gravitational attraction between galaxies.

Yes, but the article is indeed unclear about this. In particular this line:

>The farther away that galaxies were, the faster they were receding.

This is already the case in Hubble's law, which says that the velocity is proportional to the distance. Hubble's constant is the proportionality constant and thus the expansion rate.

Riess found that the Hubble constant is not constant. Instead, the expansion rate is increasing over time.

How many journalism majors did you encounter in undergrad who knew how to apply second derivatives to Physics problems? (I've given up on pop science articles - podcasts with experts interviewing experts has a much higher signal to noise ratio)

I wouldn't expect a journalist to apply second derivatives, but I would expect them to talk to physicists and accurately report what the physicists say. Of course, I have no real physics or astronomy education beyond high school, but I can recognize a textbook one-line description of Hubble's law and know that something's off when it's being attributed to a guy in 1998.

I have quite low expectations of journalists when it comes to anything technical or that requires expertise, but I do generally think highly of the Atlantic and think they are generally a lot better than average at it. I'm a disappointed in this one though.

>but that the rate of expansion itself is increasing over time.

Take for example galaxies running from us at "c". They happen to be exactly at 13.7B light years - coincidence? I don't think it is a coincidence, and some simple logic leads to conclusion that the same galaxies will be running from us at the same "c" say 300M years later - ie. then it will be "c" at 14B light years distance from us - which means that the Hubble constant is actually decreasing.

But further away galaxies are further back in time, so if the expansion is accelerating.. shouldn't they be going away at a slower speed, and the closer galaxies going away from us at a faster speed?

I think they're talking acceleration, not velocity? Hubble's law says more distant galaxies are receding faster than slower ones at some calculable rate, but it doesn't say the rate at which they're doing that is accelerating over time. (I do find it kind of shocking that one can prove this without observing the same thing over a prolonged period of time.)

Disclaimer that I'm not an astronomer and might be totally wrong, but from some quick searching, it seems like the article is conflating Hubble's discovery and Riess's. Hubble's law can be true even if the expansion of the universe is slowing down, not speeding up: a galaxy twice as far away as another can be receding at twice the speed, even if that speed is decreasing over time. But it seems like Riess's discovery is that the speed is actually increasing over time. It's related to Hubble's law but not the same thing.

Frankly, the fact that I could find that out with 2 minutes of reading Wikipedia reflects pretty poorly on the author.

The Hubble Tension is not Hubble's constant.

Adam Riess might be right, but for reasons he won‘t like. Much of his measurements (and also his Noble prize) depend on the supernovae 1a, which according to the standard model are standard candles. That means it is assumed they always reach the same luminosity, so they can be used to measure distances in the universe (the fainter they are, the farther away they are).

However what if supernovae 1a are not standard candles and their luminosity varies over a much greater range? Then a lot of distance measurements from Riess et. al. are wrong. I belief that scenario to have higher probability than many of the proposed alternatives. But Riess cannot see that, because it would put into question his lifes work.

I guess they've watched the expansion between two galaxies over time and found it increasing?

Otherwise, the fact that "the further away from us they are, they faster they were receding" made me think of this way:

-the further away they are, the longer the light had to travel to get here

-the longer the light had to travel, the longer it took to get to us

-the longer it took to get to us, the further into the past we are looking

-the further into the past we look (further distances), the faster they are receding - doesn't that imply it was faster in the past? The further past we look, the faster it is. The closer we look to home (the closer to "now"), the slower it is.

Galaxies farther away are receding faster because they are older. What Riess found is that it isn't linear with distance, they are moving away at an accelerating rate. I assume this shows up with close galaxies moving faster than they should.

The acceleration was really fast after Big Bang, but slowed down. It was assumed that it would flatten out and expand at constant rate.

I wish the journalist asked the leading scientists in the field “Before you learned of the Hubble tension, what did you think the odds were of the standard model being correct? And after?”

And everything would be much clearer.

I think it's still not universal among astronomers that the Hubble tension is real. (Though the tide seems to have shifted in the last two years or so with the median astronomer reluctantly accepting that the Hubble tension is probably real.)

All of this is wildly exciting - I wonder if this is how people in the 1800s and 1930s felt like, as electricity and nuclear science was going through its hey-day.

Your time's a bit off - electrification didn't really take off until the early 20th century and nuclear applications outside of weapons until the 1950s and 1960s.

My grandmother grew up when cars were scarce, electric wires were stapled to the wall, and indoor plumbing was for city folk. She hit a certain level of technological advancement and then just stopped, probably around the 1980s. She died last year, having never used the Internet or a computer and still using a console TV (with an adapter box installed by the cable company).

The description of how the universe is expanding sounds like how an explosion expands. Rapidly then slower until it settles down and stops (with no collapse at the end, just matter in place where it landed). I wonder if that could be the closest analogy?

An explosion has a center. I'm not a cosmologist, but my understanding is that the universe expands everywhere and at a rate that's in fact accelerating rather than slowing down.

What does the has a center comment have to do with the rest of the comment? The big bang had a center too. That doesn't mean anything in the context though.

The other two sibling comments expressed some doubt, but I can tell you with absolute certainty that in the standard model, and to the best of our knowledge in reality, the big bang did not have a center.

This makes no sense to me. Are we saying the universe existed before the big bang? The big bang went boom and everything started expanding from it. How is it not the center?

It's a 4D spacetime, not a 3D space.

Start with a tiny sphere. Expand it. The sphere gets bigger, but no point on the 2D-like surface is the centre.

It's like that, but the surface is a 4D spacetime.

You can't use your imagination to visualise this. But you can use math to describe it.

Whether there's some kind of ultradimensional hypercentre is a different question. Even if there was, it wouldn't be accessible from this universe.

And don't forget we don't have a clue what spacetime is. Relativity has some nice descriptions of what it does, but there's no fundamental explanation of how the universe generates the phenomena we call position, time, and distance.

That is the best explanation I've ever heard about that "where is the center question". Thank you.

Perhaps some day I'll be able to wrap my head around your closing caveat. I suspect any question I ask on that would be another "where is the center" type question.

We observe that the matter density in the universe is decreasing with time. As far as we know, this looks the same from every point in the universe: galaxies move away from each other. The speed at which they move away from each other doesn’t depend on where in the universe you are. (It only depends on the time, as the speed is slowly increasing.) There is no center from which they move away from. Or alternatively, every point in the universe is such a center. It’s like when zooming into a grid. It doesn’t matter at which point of the grid you zoom in, the grid expands in the same way regardless. The grid has no center, and also no boundary.

Due to the laws of general relativity, extrapolating that observation into the past, the implication is that the matter in the universe was ever denser the further you go into past. Furthermore, there is a point in time where it becomes infinitely dense. This is what we call the Big Bang. Because our equations break down at that point, we don’t know what happened at that point in time, or before, or whether there was a before. However, observational evidence like the cosmic microwave background strongly support the theory: https://en.wikipedia.org/wiki/Big_Bang#Observational_evidenc...

Note that “infinitely dense” does not imply that the universe shrinks to a single point at that time. Rather, it was infinitely dense at every point. (Again, this is like zooming out from an infinite grid infinitely far. The grid always remains infinitely large.) This means that the Big Bang happened everywhere at once. It’s a point in time, not a location.

The Big Bang is not a physical explosion and the universe is not a balloon. All space was condensed together, but space is (to our current ability to measure it) topologically flat and infinite. It was still infinitely big in every dimension, it was just unfathomably dense.

The expansion that's occurring is that the space between things is growing. But it's every space between everything all at once, everywhere.

There is no physical equivalent.

No, we are not saying that. We are saying that the entirety of space - and not just its contents - have been compressed into a point (ignoring quantum gravity for now). Any two points in space have been arbitrarily close if you play the movie backwards sufficiently close to the first moment.

I thought the big bang had no center because there is no edge. Rather expansion was of space itself that happened everywhere.

No, it’s not space itself. Relative to what would it expand? It’s galaxies moving away from one another, which necessarily increases the space between them.

I don't think the big bang or the universe ever had a center.

Riess' original discovery is the opposite: The universe expands faster and faster over time.

Is there any succinct publication of his observations?

There's a "general audience" review by the man himself.

> https://arxiv.org/abs/2211.04492

Very well written. I felt like reading a good novel.

I'm not an astrophysicists, but dark energy and dark matter have always felt like "fudge factors" to me.

Paywall bypassed:

https://archive.ph/51R4k

> He compared the theory to an egg that is breaking. “It’s not going to cleave neatly in one place,” he said. “You would expect to see multiple cracks opening up.”

Someone needs to send him an https://en.wiktionary.org/wiki/Eierschalensollbruchstellenve...

interesting was trying to figure out how it works looks like the metal bead you raise and drop it

Genau!

“It is easier for a cannibal to enter the Kingdom of Heaven through the eye of a rich man's needle than it is for any other foreigner to read the terrible German script.”

Mark Twain

I only recently learned what this is actually referring to, after scouring archive.org for Spanish, French, and German language versions of Lingua Latina per se Illustrata. Twain is being perfectly literal, though these days we'd narrow the debate to typeface as people rarely handwrite these days. Example: https://archive.org/details/erstesdeutsches00wormgoog/page/n... When first opening that book, I was like, "what kind of inanity is this!?" The same author wrote Spanish and French versions of that book, but both were printed using a perfectly familiar Latin typeface. After reading about the issue, I can sort of appreciate why that typeface was chosen, though it definitely steepens the learning curve.

There was a centuries long debate in Germany (and Germanic lands) over this issue. See https://en.wikipedia.org/wiki/Antiqua%E2%80%93Fraktur_disput... for info about the debate over typeface specifically. TL;DR: The Nazis resolved the dispute by fiat, in an odd twist of history settling on the Latin typeface.

(For typeface enthusiasts, I apologize for any poor use of terminology.)

These days, even here in Germany, Fraktur script is mainly used to determine when you're finally doing serious mathematics.

That's super interesting context that I didn't know. Here I thought he was using script as a metonym of sorts for 'language'.

Thanks

I remember that font from Walt Kelley's Pogo - used for the undertaker vultures

They may certainly have a point, but many Nobel Prize winners do have a track record of going off the deep end which is something to keep in mind when an article tries to justify their points using Noble Prizes

edit: I'm just trying to say that "Having a Nobel Prize" doesn't mean they are an authority on subjects they talk about since many wen't on to promote homeopathy, aliens, believed aids wasn't caused by HIV, don't believe in climate change, etc."

https://en.wikipedia.org/wiki/Nobel_disease

This is a decently-well documented observation. (I hesitate to call it a "phenomenon" as that would imply an actual casual mechanism.)

Reminds me of Roger Penrose more recently. When Nobel Prize winners start making YouTube rounds, you have a good indicator of someone going of the deep end. Thank God, Eric Weinstein doesn't have a Nobel Prize...

How has Penrose gone off the deep end?

His theories about quantum consciousness...

Penrose published “The Emperor’s New Mind” some 16 years before YouTube existed as a website, so you may need to clarify which particular theories about quantum consciousness you’re referring to.

If even getting a Nobel Prize isn't enough to protect someone from being accused of deviating from orthodoxy and therefore ipso facto "off the deep end", then the entire claim the science apparatus makes about being all about ideas and not about orthodoxy is falsified, and all subsequent beliefs in a belief net based on that proposition need to be updated accordingly.

I think this is a misunderstanding of the underlying issue.

It isn't about protection from straying from some level of orthodoxy. It's about people who are incredibly brilliant in one area of their life - and yet be incredibly dumb in another. I've always seen Linus Pauling as an interesting example of this. Brilliant in some ways, but going all in on Vitamin C is just weird.

I see the basic claim as - sometimes these prizes - well intentioned as they are - may lift critical guard rails that unintentionally let them drive off into their weeds. They go deeper and harder into the weeds because the prestige that comes with these prizes creates a halo effect that blunts or hides critical criticism that can no longer reach them.

"Being all about ideas" implies that whether someone has a Nobel prize should play a very small role when evaluating an idea. If the idea sounds implausible, it's OK to say so, no matter whose idea it is. Some people will still look into it.

Someone getting the Nobel Prize and then being assumed correct from then on would be approximately the opposite of science.

They can put their ideas out there, and people can evaluate them on their merits just fine, with maybe a bias towards the ideas being interesting due to the source. What's wrong with that?

I mean some of these are just easily problematic and wrong, so its better to take their good ideas and not the rest.

Like these are just 2 cases of a number of examples

1993 chemistry doesn't believe AIDS is caused by HIV, doesn't believe in Climate Chiange, believes in astrology, thinks he talked to talking alien racoon

2008 medicine founded their own journal and claimed viruses emitted radio waves to arrange water in nanostructure that let you teleport DNA though Homeopathy and also claims vaccines cause autism.

Eh, I think that is just the result of more attention/funding. Plenty of scientists have wacky ideas (very much encouraged!) that do not pan out upon further investigation. If you are a no name lab that tries a novel idea that fails, nobody knows or cares. “Celebrity” scientist with a failed idea and now you are off the deep end.

Is there a correlation between being born in Superfund sites and being a Nobel Prize winner?

The blaming of cliques of scientists for rejecting alternate ideas was cliche and kind of a red flag.

That does happen, of course. Science is conservative because if we have a theory that is a good fit to the data it should take a lot of evidence to unseat that theory and the new one must also fit all the data the old one did. (Unless some data was wrong, but that also takes evidence.)

But this is also something every crank says, and loudly. The more obsessed and loud someone is with a conspiracy against them the more they sound like a crank.

Was Einstein or quantum theory instantly rejected and held down forever by a conspiracy? Not really. There were skeptics but I seem to recall these ideas taking hold pretty fast because they fit a lot of anomalous data very well.

Having hesitancy of any new theory that directly conflicts with the known/accepted theories is not a bad thing. Telling someone that their theory is so different than what everyone else thinks that they might want to go back and double/triple check just in case someone forgot to carry a one or something else simple/embarrassing is just a CYA bit of advice. Other quotes like "extraordinary claims require extraordinary evidence" would also be apropos.

Agreed. People point to the edge cases where orthodoxy and conformity crushed the brilliant innovator but for every one of those there are 1000 cranks or embittered dead end researchers claiming that only a conspiracy prevented their genius from being recognized.

This sort of argument implies that Riess must have turned into a crank since his Nobel prize winning turn... Seems unlikely though doesn't it?

Happens so often they call it the Nobel curse.

It’s related to why famous celebrities and billionaires often lose their minds. Human success is self limiting. It begets failure by convincing people they are “special.” Pride comes before a fall is not because god punishes people for pride or something. It’s a statement of cause and effect. Pride causes a fall.

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