Conflicting Values For Hubble Constant Not Due To Measurement Error, Study Finds (arstechnica.com) 64
Jennifer Ouellette reports via Ars Technica: Astronomers have made new measurements of the Hubble Constant, a measure of how quickly the Universe is expanding, by combining data from the Hubble Space Telescope and the James Webb Space Telescope. Their results confirmed the accuracy of Hubble's earlier measurement of the constant's value, according to their recent paper published in The Astrophysical Journal Letters, with implications for a long-standing discrepancy in values obtained by different observational methods known as the "Hubble tension."
There was a time when scientists believed the Universe was static, but that changed with Albert Einstein's general theory of relativity. Alexander Friedmann published a set of equations showing that the Universe might actually be expanding in 1922, with Georges Lemaitre later making an independent derivation to arrive at that same conclusion. Edwin Hubble confirmed this expansion with observational data in 1929. Prior to this, Einstein had been trying to modify general relativity by adding a cosmological constant in order to get a static universe from his theory; after Hubble's discovery, legend has it, he referred to that effort as his biggest blunder. The article notes how scientists have employed different methods to calculate the Hubble Constant, including observing nearby celestial objects, analyzing gravitational waves from cosmic events, and examining the Cosmic Microwave Background (CMB). However, these approaches yield differing values, highlighting the challenge in pinning down the constant precisely. A recent effort involved making additional observations of Cepheid variable stars, correlating them with the Hubble data. The results further confirmed the accuracy of the Hubble data.
"We've now spanned the whole range of what Hubble observed, and we can rule out a measurement error as the cause of the Hubble Tension with very high confidence," said co-author and team leader Adam Riess, a physicist at Johns Hopkins University. "Combining Webb and Hubble gives us the best of both worlds. We find that the Hubble measurements remain reliable as we climb farther along the cosmic distance ladder. With measurement errors negated, what remains is the real and exciting possibility that we have misunderstood the Universe."
There was a time when scientists believed the Universe was static, but that changed with Albert Einstein's general theory of relativity. Alexander Friedmann published a set of equations showing that the Universe might actually be expanding in 1922, with Georges Lemaitre later making an independent derivation to arrive at that same conclusion. Edwin Hubble confirmed this expansion with observational data in 1929. Prior to this, Einstein had been trying to modify general relativity by adding a cosmological constant in order to get a static universe from his theory; after Hubble's discovery, legend has it, he referred to that effort as his biggest blunder. The article notes how scientists have employed different methods to calculate the Hubble Constant, including observing nearby celestial objects, analyzing gravitational waves from cosmic events, and examining the Cosmic Microwave Background (CMB). However, these approaches yield differing values, highlighting the challenge in pinning down the constant precisely. A recent effort involved making additional observations of Cepheid variable stars, correlating them with the Hubble data. The results further confirmed the accuracy of the Hubble data.
"We've now spanned the whole range of what Hubble observed, and we can rule out a measurement error as the cause of the Hubble Tension with very high confidence," said co-author and team leader Adam Riess, a physicist at Johns Hopkins University. "Combining Webb and Hubble gives us the best of both worlds. We find that the Hubble measurements remain reliable as we climb farther along the cosmic distance ladder. With measurement errors negated, what remains is the real and exciting possibility that we have misunderstood the Universe."
Global warming (Score:3, Funny)
Re:Global warming (Score:4, Funny)
Like that empty bag on top of your neck.
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I think it was insult comedy, empty bag head! :D
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It never works on the internet. I got it, but I knew right away that some wouldn't. And I've been one of those often enough as well ;)
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Good one.
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Global warming only applies to the globe. But the earth is a disc, and not a globe, so global warming doesn't apply. Quit thinking the earth is a globe.
Likewise, global warming is not universe warming. You need universe warming for the increased expansion rate.
(/s poking fun at both flat earthers while I'm at it).
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At the same time; things cool down as the expand. Any refrigerator knows this.
Fun MOTD (Score:5, Funny)
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I have never seen that before, on /. or not. But I see the validity in that.
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How much do they need for a new telescope? (Score:2)
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Or, in the case of particle physicists, how much money do they need for a new accelerator?
There is a difference. Each telescope actually does a lot of work.
Particle accelerators now might find one thing that they already knew existed.
Hubble and now Web continue to provide "scientists are stunned" discoveries.
Latest accelerator found a Higgs Boson.
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Latest accelerator found a Higgs Boson.
It actually so many of them that their existence was proven by the statistic abberation they caused.
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Next up lets build an accelerator around the entire earth and see if we can prdouce anti atter in quantity to use as space fuel.
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How would you harness the gamma rays from matter antimatter.
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How would you harness the gamma rays from matter antimatter.
I'd expose scientists to it to create an army of Incredible Hulks.
Excellent Illustration (Score:4, Interesting)
Re:Excellent Illustration (Score:5, Informative)
The Hubble tension is a critical, a deciding problem in current Cosmology, and there will be a pre-Hubble-tension cosmology and a post-Hubble-tension cosmology, which will have a vastly different view on the Big Bang, the expansion of the Universe, the Cosmological constant and Dark Energy.
So yes, crisis is the perfect term for this.
Re:Excellent Illustration (Score:4, Informative)
> Because crisis is long term and severe deviation from normalcy
Show me a dictionary that includes that definition...
> Proper cosmology would at least depend on quantum gravity
Quantum gravity has not yet been experimentally verified, so you can't even say it exists. "Proper cosmology" is under no obligation to consider your pet theory until you have some actual evidence to suggest it's real. (Even then, the offered explanation for the observation may be subject to debate.)
What we DO know, is we get two different answers for how fast the universe is expanding depending on how we measure it. This suggests something very fundamental in our current understanding might be wrong, hence the word "crisis". You don't just slap "quantum" on it and call it good though...
=Smidge=
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> I'm merely saying that we shouldn't expect to have an understanding in the first place.
Except we DO have an understanding... we have made observations and developed a model that explains those observations with adequate predictive power to be diagnostically useful. However, the model we've been using relies on measurements that give different results depending on how they are made, and we don't (yet) know why. The crisis part comes from how the disagreement in results is getting worse as measurements g
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Rather like the way light can appear to be either particles or waves depending on how you measure it? I'm not suggesting a connection, here, just pointing out that this isn't the first time we've found a duality like this.
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> Rather like the way light can appear to be either particles or waves depending on how you measure it?
No. As in we literally get different answers depending on the method used.
One method of measuring distances is to use objects in other galaxies that have a known brightness, like a specific type of star or supernova. By comparing the observed brightness to what we know it should be, we can determine how far away it is. Combine that with a phenomena called red shift (the doppler effect applied to electro
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The fact that they differ at all is interesting, just curious whether we're talking about a few percent, or a few orders of magnitude, or what?
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Re:Excellent Illustration (Score:5, Informative)
How big is the discrepancy? The fact that they differ at all is interesting, just curious whether we're talking about a few percent, or a few orders of magnitude, or what?
A few percent.
Wikipedia has a good graph of Hubble constant measurements here: https://upload.wikimedia.org/w... [wikimedia.org] (but not including this just-published result.) The discripancy is between "early universe" measurements (in red, about 68.3 k/s per MPc) and "late universe" measurements (in blue, about 73) on the right side of the graph.
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I appreciate your post and I would add another consideration that answers the question, "Why do the numbers change with distance?" The answer is "standard candles." Close to Earth, we can use direct observation, and those markers have anomalies, due to local gravity influences. As we climb the distance ladder, we depend on standard candles that, "on average," exhibit predictable consistencies.
An obvious problem is the word, "average." That introduces wiggle room; a variation that we don't want. As we move o
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The fun thing, for me, is that I did some modeling for my Masters degree and my model didn't match either the other theoretical models, or the models from observation. It was in between them.
This was 20+ years ago, and they still haven't managed to align theory and observation
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For those not keeping track of this conundrum, Dr Becky [youtube.com] (PhD astrophysicist) on Youtube has a whole series of videos [youtube.com] on the crisis in cosmology, particularly how there are these two independent estimates of the Hubble constant that are stubbornly different [youtu.be].
Dr Becky might be catering to the crowd that believes with every new discovery or every unsolved physics issue, that "scientists are stunned". Pop culture science maybe? I'll have to take a look.
Crisis in Cosmology? A crisis for physicists is when an argument breaks out over which pizza delivery to get.
Re:Excellent Illustration (Score:4, Informative)
No. She's providing an insider perspective (her own work is in this area) that is thankfully free of the "scientists are stunned" nonsense. She presents popular science in the sense that she makes complicated subjects accessible to non-scientists, not in the sense that she sensationalizes things.
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One potential explanation for this H. constant discrepancy might be the super-void our galaxy is on the "edge" on: PBS Space Time: Can The Crisis in Cosmology Be SOLVED With Cosmic Voids? [youtube.com]
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..as they constantly, relentlessly keep droning on and on about ongoing inflation.
Not when they are in power though.
Confusing summary (Score:2)
Intermingles Hubble the person with Hubble the constant with Hubble the telescope.
Re:Confusing summary (Score:5, Funny)
Intermingles Hubble the person with Hubble the constant with Hubble the telescope.
Hubble's Hubble measured the Hubble. What's confusing about it?
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Makes you wonder (Score:1)
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A little intellectual modesty never hurt anyone.
Did a double-take (Score:2)
I did a double-take when I read this. I haven't seen Jennifer Oueletteâ(TM)s name in years! I was an avid reader of Cocktail Party Physics, read a couple of her books, but haven't seen her in the scientific circles in what seems like a decade. Flash back Tuesday?
"Dark" means it can't be seen (Score:3)
First, "dark" implies it cannot be known,
Not really. Dark implies that it doesn't emit light or reflect it. That's all.
Basically, in this context it's called "dark" because it can't be seen in visible light (nor IR, UV, or radio frequency).
... Secondly, "matter" presupposes that whatever it is that is causing the universe to expand is an object; maybe it's just a force.
People have proposed that (or, more specifically, that it's a different force law than we know). This is an alternative suggesting that dark matter doesn't exist.
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Dark can also mean unknown. Darkest Africa, dark side, meaning far side, of the Moon, both of which we eventually got knowledge off.
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Not can not be known, rather currently unknown. We did come to know darkest Africa.
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Re:"Dark Matter" is a dumb name (Score:4, Informative)
First, "dark" implies it cannot be known, when clearly the situation is merely we just aren't looking in the right places.
No. As the topic is physics "dark" means it does not interact with light or an EM field. This is different than normal or baryonic matter that compromise what the Earth and human are made of. "Dark" does not describe the status of knowledge around the matter.
Secondly, "matter" presupposes that whatever it is that is causing the universe to expand is an object; maybe it's just a force.
Again, no. Matter means it is not energy. The effect of expansion of the universe is not limited to whether it is or is not matter. Also there is dark energy which is larger than dark matter.
And lastly, it sounds more like a Hollywoke Special Operations code name than a somber topic of interstellar physics.
No. The first discussions about dark matter was from lectures by Lord Kelvin (Kelvin temperature scale) in 1884 in a series of lectures. In 1906 Henry Poincaré (Poincare conjecture [wikipedia.org]) suggested dark matter account for some discrepancies which was supported by Jacobus Kapteyn in 1922. It sounds like you have no area of expertise in physics but it must be "woke" because you don't know the history of it.
There was a time when science wasn't brain-dead (Score:1)
An expanding universe is non-sensical. You all would realize that if you hadn't been brain-washed and dumbed down in government schools your entire lives.
Instead, you should be thinking about: what *is* "space"? Is there any smallest unit, and if so how could that possibly work? Largest unit? Or infinitely fractal?
This expanding universe stuff is a religious pseudoscience.
We live in a dark age. Future generations will laugh at our "consensus" ideas... if we haven't descended into full-on idiocracy
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Re: There was a time when science wasn't brain-dea (Score:2)
Let me guess, you subscribe to either flat earth or electric universe or whatever it's called.
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The universe is expanding, get over it. But most people see the universe as flat, as in 3D-flat, this is a misconception because it's a hard concept to wring your brain to understand without at least a couple of headaches, if the universe on the other hand is the surface of a sphere, it's easy to see how such a sphere can be expanding. I suspect it expands with a fixed rate, that's just me. Also I believe we (the scientific society consensus (some opposition exists)) got the age/size of the universe all wro
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I suspect it expands with a fixed rate, that's just me.
Evidence indicates it's expanding at an increasing rate.
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Yes, it would look like that from this point of view. I am not convinced that the model is correct, and calculations based on a faulty model might get skewed results.
The main issue is that it's hard to measure space expansion on very distant objects reliably in the short delta t we have had.
An accelerating expansion would make our universe even unfriendlier to travel, so I might base my beliefs on a more optimistic view.
not news (Score:3)
That the disparate estimates of the Hubble constant are very unlikely to be experimental error has been known for something like a year or more.
Hubble Tension Calculations (Score:4, Insightful)
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