How old is the universe? New studies disagree by a billion years

The universe likes to play coy about its age, but astronomers believe they have a pretty good idea of the range. Now, a series of new studies has investigated the question using different methods – and they’ve come up with two different answers, separated by more than a billion years.

more…

Tau.Neutrino said:

How old is the universe? New studies disagree by a billion years

The universe likes to play coy about its age, but astronomers believe they have a pretty good idea of the range. Now, a series of new studies has investigated the question using different methods – and they’ve come up with two different answers, separated by more than a billion years.

more…

> They recalibrated an existing tool for measuring distance, called the baryonic Tully-Fisher relation, which works independently to the Hubble constant. Starting with Spitzer data of the distances of 50 galaxies, they used this to estimate the distances to another 95 galaxies. This then provides a new, supposedly more-accurate foundation for calculating the Hubble constant, and by extension, the age of the universe.

“supposedly” is right. Astronomers haven’t used a galaxy sample as small as 50 or 95 galaxies since the 1970s. Get back to me when your sample size is more than 1,000 galaxies. Preferably of the order of 50,000.

mollwollfumble said:

Tau.Neutrino said:

How old is the universe? New studies disagree by a billion years

The universe likes to play coy about its age, but astronomers believe they have a pretty good idea of the range. Now, a series of new studies has investigated the question using different methods – and they’ve come up with two different answers, separated by more than a billion years.

more…

> They recalibrated an existing tool for measuring distance, called the baryonic Tully-Fisher relation, which works independently to the Hubble constant. Starting with Spitzer data of the distances of 50 galaxies, they used this to estimate the distances to another 95 galaxies. This then provides a new, supposedly more-accurate foundation for calculating the Hubble constant, and by extension, the age of the universe.

“supposedly” is right. Astronomers haven’t used a galaxy sample as small as 50 or 95 galaxies since the 1970s. Get back to me when your sample size is more than 1,000 galaxies. Preferably of the order of 50,000.

Setting the Tully-Fisher results aside as the result of using too few galaxies, there are still claims of a disagreement, as for instance in the Scientific American article

https://www.scientificamerican.com/article/how-a-dispute-over-a-single-number-became-a-cosmological-crisis/

Note below how the error bars (one standard deviation) on the CMB measurements are way smaller than that based on either cepheids or red giant stars. The result from the cosmic microwave background has to be taken as definitive, despite the 4 sigma deviation from the value obtained from cepheids.

In addition The age of the universe can’t be less than that measured from the CMB because then the age of individual white dwarf stars would be too long relative to the ago of the universe.

What is the evidence that the “Hubble Constant” is really constant?

The Rev Dodgson said:

What is the evidence that the “Hubble Constant” is really constant?

Isn’t change the only constant?

The Rev Dodgson said:

What is the evidence that the “Hubble Constant” is really constant?

It isn’t. It’s time varying.

dv said:

The Rev Dodgson said:

What is the evidence that the “Hubble Constant” is really constant?

It isn’t. It’s time varying.

They should give it a new name then.

So if this constant is varying, how can measurement of a single quantity such as the CMBR provide an age of the Universe?

The Rev Dodgson said:

dv said:

The Rev Dodgson said:

What is the evidence that the “Hubble Constant” is really constant?

It isn’t. It’s time varying.

They should give it a new name then.

So if this constant is varying, how can measurement of a single quantity such as the CMBR provide an age of the Universe?

By being aware of the level of variation?

roughbarked said:

The Rev Dodgson said:

dv said:

It isn’t. It’s time varying.

They should give it a new name then.

So if this constant is varying, how can measurement of a single quantity such as the CMBR provide an age of the Universe?

By being aware of the level of variation?

I guess they must do that somehow.

Perhaps I should read up how they do it.

The Rev Dodgson said:

roughbarked said:

The Rev Dodgson said:

They should give it a new name then.

So if this constant is varying, how can measurement of a single quantity such as the CMBR provide an age of the Universe?

By being aware of the level of variation?

I guess they must do that somehow.

Perhaps I should read up how they do it.

Perhaps I should as well.

The Rev Dodgson said:

dv said:

The Rev Dodgson said:

What is the evidence that the “Hubble Constant” is really constant?

It isn’t. It’s time varying.

They should give it a new name then.

Some prefer Hubble parameter.

So if this constant is varying, how can measurement of a single quantity such as the CMBR provide an age of the Universe?

By itself, it can’t, though that’s an important input to the model.

The Rev Dodgson said:

dv said:

The Rev Dodgson said:

What is the evidence that the “Hubble Constant” is really constant?

It isn’t. It’s time varying.

They should give it a new name then.

So if this constant is varying, how can measurement of a single quantity such as the CMBR provide an age of the Universe?

The evidence that the Hubble constant is constant is overwhelming.

Quite apart from the observational evidence, the only thing that influences it is gravity and dark energy. Gravity is too weak to have any measurable influence at all, and dark energy only has an effect way out beyond the reach of any distance measure other than supernovae as standard candles. So it’s constant out to the range of the distance ladder from both Cepheids and the Tully-Fisher relationship.

As for the the CMB, both dark energy and gravity are already taken into account in the calculation of the modern Hubble constant. So there’s no discrapancy from that cause.

mollwollfumble said:

The Rev Dodgson said:

dv said:

It isn’t. It’s time varying.

They should give it a new name then.

So if this constant is varying, how can measurement of a single quantity such as the CMBR provide an age of the Universe?

The evidence that the Hubble constant is constant is overwhelming.

Quite apart from the observational evidence, the only thing that influences it is gravity and dark energy. Gravity is too weak to have any measurable influence at all, and dark energy only has an effect way out beyond the reach of any distance measure other than supernovae as standard candles. So it’s constant out to the range of the distance ladder from both Cepheids and the Tully-Fisher relationship.

As for the the CMB, both dark energy and gravity are already taken into account in the calculation of the modern Hubble constant. So there’s no discrapancy from that cause.

So dv is wrong?

Should we have a thread to discuss this?

“Quite apart from the observational evidence, the only thing that influences it is gravity and dark energy.”

But if the observational evidence gives significantly different ages for the Universe, doesn’t that suggest that the assumption that “the only influences on the Hubble Constant are gravity and dark matter” may be wrong?

The Rev Dodgson said:

mollwollfumble said:

The Rev Dodgson said:

They should give it a new name then.

So if this constant is varying, how can measurement of a single quantity such as the CMBR provide an age of the Universe?

The evidence that the Hubble constant is constant is overwhelming.

Quite apart from the observational evidence, the only thing that influences it is gravity and dark energy. Gravity is too weak to have any measurable influence at all, and dark energy only has an effect way out beyond the reach of any distance measure other than supernovae as standard candles. So it’s constant out to the range of the distance ladder from both Cepheids and the Tully-Fisher relationship.

As for the the CMB, both dark energy and gravity are already taken into account in the calculation of the modern Hubble constant. So there’s no discrapancy from that cause.

So dv is wrong?

Should we have a thread to discuss this?

“Quite apart from the observational evidence, the only thing that influences it is gravity and dark energy.”

But if the observational evidence gives significantly different ages for the Universe, doesn’t that suggest that the assumption that “the only influences on the Hubble Constant are gravity and dark matter” may be wrong?

Where “dark matter” = “dark energy”

(but wouldn’t dark matter come into the picture anyway?)

The Rev Dodgson said:

mollwollfumble said:

The Rev Dodgson said:

They should give it a new name then.

So if this constant is varying, how can measurement of a single quantity such as the CMBR provide an age of the Universe?

The evidence that the Hubble constant is constant is overwhelming.

Quite apart from the observational evidence, the only thing that influences it is gravity and dark energy. Gravity is too weak to have any measurable influence at all, and dark energy only has an effect way out beyond the reach of any distance measure other than supernovae as standard candles. So it’s constant out to the range of the distance ladder from both Cepheids and the Tully-Fisher relationship.

As for the the CMB, both dark energy and gravity are already taken into account in the calculation of the modern Hubble constant. So there’s no discrapancy from that cause.

So dv is wrong?

Should we have a thread to discuss this?

“Quite apart from the observational evidence, the only thing that influences it is gravity and dark energy.”

But if the observational evidence gives significantly different ages for the Universe, doesn’t that suggest that the assumption that “the only influences on the Hubble Constant are gravity and dark matter” may be wrong?

Nope.

Am I right in assuming that you are mostly unfamiliar with the furore over disagreements about the value of the Hubble constant from 1930 to 1980?

For starters, Hubble’s original measurement of the Hubble constant was out by a factor of eight, a value of “500” when it should have been “62”. This is so far out that I almost cringe every time the word “Hubble” is used before “constant”. This totally crap result continued to be used until the 1950s.

mollwollfumble said:

Nope.

Am I right in assuming that you are mostly unfamiliar with the furore over disagreements about the value of the Hubble constant from 1930 to 1980?

You are almost right. I am entirely unfamiliar with that furore.

I’m not sure what it has to do with the best estimate of the constant now though.

>But if the observational evidence gives significantly different ages for the Universe

…because the observational techniques used, and their interpretation, lead to different values for the Hubble constant. It’s been a problem for a long time.

mollwollfumble said:

Am I right in assuming that you are mostly unfamiliar with the furore over disagreements about the value of the Hubble constant from 1930 to 1980?

For starters, Hubble’s original measurement of the Hubble constant was out by a factor of eight, a value of “500” when it should have been “62”. This is so far out that I almost cringe every time the word “Hubble” is used before “constant”. This totally crap result continued to be used until the 1950s.

Some more on this. Perhaps you know it better as the controversy over the age of the universe, but that didn’t become part of the battle in the early stages.

Hubble constant controversy/furore.

Leaving aside the to-ing and fro-ing over the curvature of the universe.
Hubble constant is most frequently quoted in km/s/Mpc

1920 “The great debate” about whether spiral galaxies were within or outside the Milky Way

1922, 1924, 1927 The Friedmann–Lemaître equation gives a link between the Hubble constant and the age of the universe.

1925 Strömberg finds that the Milky Way has a high peculiar velocity relative to nearby nebulae of order 500 km/s (Later this will be tied into what is now called the Great Attractor).

1926 Hubble comes up with a luminosity-magnitude relationship for each type of galaxy. And from there concludes that the universe is static, finite (positively curved), with a radius of 2.7*10^10 parsecs containing 3.5*10^15 normal galaxies.

1929 Hubble & Humason gets 558 km/s/Mpc. (This actually gives an age for the universe of less than half the age of the Earth, but that isn’t realised for a while).

1931 Oort puts error bars on the Hubble constant, errors are of the rough order of ±50%.

Oort’s graph.

1933 Zwicky supports Hubble against Oort, saying that use of the Hubble constant can “up to now predict the redshift in every case up to a few percent, even for distances that were greater by up to thirty times than the ones originally considered.” Zwicky uses galaxy clusters rather than individual galaxies to calculate the constant.

Zwicky’s graph.

1939 Gamow vs Jeans. Jeans says that the calculation by Hubble is wrong, that the Hubble constant has to be higher to prevent instability. Gamow supports Hubble. (Jeans’ correction is in the wrong direction).

1948 Bondi. Quotes a value of 101 miles per sec. per million light years for the Hubble constant. That’s 530 km/s/Mpc. In agreement with Hubble (1929).

(By 1948, still nobody had noticed that the age of the Earth is more than twice the age of the universe).

1961 Jagjit Singh in “Modern Cosmology” quotes a value of 19 miles per sec. per million light years for the Hubble constant. That’s 100 km/s/Mpc.

Singh’s graph.

To be continued.
(I still haven’t covered controversies due to: calculation using the brightest galaxy in a cluster, the realisation that Cepheids come in two types, the ages of cooling white dwarfs exceed the age of the universe, how the discovery of dark matter made the problem much worse, the final solution from the discovery of dark energy, COBE, WMAP and Planck).

(I only just noticed, ALL early calculations of the Hubble constant relied heavily on the Virgo cluster of galaxies. This gives ratshit results because the great attractor is aligned with this cluster, and is not too far off in direction from the other big nearby cluster – the Fornax cluster).

mollwollfumble said:

mollwollfumble said:

Am I right in assuming that you are mostly unfamiliar with the furore over disagreements about the value of the Hubble constant from 1930 to 1980?

For starters, Hubble’s original measurement of the Hubble constant was out by a factor of eight, a value of “500” when it should have been “62”. This is so far out that I almost cringe every time the word “Hubble” is used before “constant”. This totally crap result continued to be used until the 1950s.

Some more on this. Perhaps you know it better as the controversy over the age of the universe, but that didn’t become part of the battle in the early stages.

Hubble constant controversy/furore.

Leaving aside the to-ing and fro-ing over the curvature of the universe.
Hubble constant is most frequently quoted in km/s/Mpc

1920 “The great debate” about whether spiral galaxies were within or outside the Milky Way

1922, 1924, 1927 The Friedmann–Lemaître equation gives a link between the Hubble constant and the age of the universe.

1925 Strömberg finds that the Milky Way has a high peculiar velocity relative to nearby nebulae of order 500 km/s (Later this will be tied into what is now called the Great Attractor).

1926 Hubble comes up with a luminosity-magnitude relationship for each type of galaxy. And from there concludes that the universe is static, finite (positively curved), with a radius of 2.7*10^10 parsecs containing 3.5*10^15 normal galaxies.

1929 Hubble & Humason gets 558 km/s/Mpc. (This actually gives an age for the universe of less than half the age of the Earth, but that isn’t realised for a while).

1931 Oort puts error bars on the Hubble constant, errors are of the rough order of ±50%.

Oort’s graph.

1933 Zwicky supports Hubble against Oort, saying that use of the Hubble constant can “up to now predict the redshift in every case up to a few percent, even for distances that were greater by up to thirty times than the ones originally considered.” Zwicky uses galaxy clusters rather than individual galaxies to calculate the constant.

Zwicky’s graph.

1939 Gamow vs Jeans. Jeans says that the calculation by Hubble is wrong, that the Hubble constant has to be higher to prevent instability. Gamow supports Hubble. (Jeans’ correction is in the wrong direction).

1948 Bondi. Quotes a value of 101 miles per sec. per million light years for the Hubble constant. That’s 530 km/s/Mpc. In agreement with Hubble (1929).

(By 1948, still nobody had noticed that the age of the Earth is more than twice the age of the universe).

1961 Jagjit Singh in “Modern Cosmology” quotes a value of 19 miles per sec. per million light years for the Hubble constant. That’s 100 km/s/Mpc.

Singh’s graph.

To be continued.
(I still haven’t covered controversies due to: calculation using the brightest galaxy in a cluster, the realisation that Cepheids come in two types, the ages of cooling white dwarfs exceed the age of the universe, how the discovery of dark matter made the problem much worse, the final solution from the discovery of dark energy, COBE, WMAP and Planck).

(I only just noticed, ALL early calculations of the Hubble constant relied heavily on the Virgo cluster of galaxies. This gives ratshit results because the great attractor is aligned with this cluster, and is not too far off in direction from the other big nearby cluster – the Fornax cluster).

(continued)

(By 1948, still nobody had noticed that the age of the Earth is more than twice the age of the universe).

1954 Harold Weaver. It is realised that the distance measured by Cepheids is wildly wrong. The distance to the centre of the Milky Way is 8.8 kiloparsecs, but if Cepheids had been used then the calculated result would have been 3.8 kiloparsecs. (This correction to Cepheid distances has flow-on effects into the Hubble constant).

1956 Sandage and Ryle, independently, Ryle used radio astronomy, but in the same issue of Scientific American. They found that the Hubble constant increased with distance. (Later shown to be false. Not only had they not gone far enough out to show any deviation from a constant value but they also got the sign of the deviation wrong, because of dark energy it decreses with distance).

1956 Jesse L Greenstein. Calculation of the cooling rates of white dwarfs. Some white dwarfs are at least 8 billion years old (This makes them a lot older than the maximum age of the universe from the then accepted value of the Hubble constant).

1958 Sandage. The final realisation that there are two types of Cepheids. One type oscillates twice as fast as the other. In addition, it has been found that what Hubble originally identified as the brightest stars is his distant galaxies are not stars at all, but HII regions. The overall result is a correction of the Hubble constant down to 75 km/s/Mpc and an overall maximum age of the universe of 13 billion years give or take a factor of two. (Finally someone got it right, there is a huge difference between the original 558 km/s/Mpc and the corrected value).

1961 Jagjit Singh in “Modern Cosmology” quotes a value of 19 miles per sec. per million light years for the Hubble constant. That’s 100 km/s/Mpc.

1961 Schmidt-Kaler. “Recently there has been much that the age of the Galaxy derived from the evolution of stars and elements might be greater than the age of the universe derived from curent cosmological theory”. We obtain for NGC 188, the galaxy’s oldest galactic cluster, an age of 11 billion years instead of Sandage’s 16 billion years. The age of the Galaxy is given as 13.2±1 billion years and elsewhere as 14.0±1.5 billion years. “Sandage has given H_0 as 75±25 km/s/Mpc based on the galactic novae.” I get, using supergiant stars, H_0 =90±30 km/s/Mpc. (The analysis is slightly flawed, it fails to accept Gamow’s discovery in 1948 that most of the universe’s helium was produced in the Big Bang, so the ages would be slightly too high).

C1970 Quasars are finally accepted as being very distant objects, whose enormous speed is due to the expansion of the universe. But at the same time it was found that quasar luminosity is so unpredictable that they unfortunately could not be used for evaluation of the Hubble constant. Some astronomers are still clinging to the belief that Hubble’s measurement of the Hubble constant was correct.

(When I talked of furore / vigorous debate earlier, I was referring primarily to the tension between the age of the universe from the measured Hubble constant and the age of the oldest stars. This tension began before 1956 (I still need a timeline for radiometric calculation of the Earth’s age), and continued on until it was mostly solved in 1998 with the discovery of dark energy. Debate since then has been more muted, but still present, as seen in the title of this thread).

mollwollfumble said:

mollwollfumble said:

mollwollfumble said:

Am I right in assuming that you are mostly unfamiliar with the furore over disagreements about the value of the Hubble constant from 1930 to 1980?

For starters, Hubble’s original measurement of the Hubble constant was out by a factor of eight, a value of “500” when it should have been “62”. This is so far out that I almost cringe every time the word “Hubble” is used before “constant”. This totally crap result continued to be used until the 1950s.

Some more on this. Perhaps you know it better as the controversy over the age of the universe, but that didn’t become part of the battle in the early stages.

Hubble constant controversy/furore.

Leaving aside the to-ing and fro-ing over the curvature of the universe.
Hubble constant is most frequently quoted in km/s/Mpc

1920 “The great debate” about whether spiral galaxies were within or outside the Milky Way

1922, 1924, 1927 The Friedmann–Lemaître equation gives a link between the Hubble constant and the age of the universe.

1925 Strömberg finds that the Milky Way has a high peculiar velocity relative to nearby nebulae of order 500 km/s (Later this will be tied into what is now called the Great Attractor).

1926 Hubble comes up with a luminosity-magnitude relationship for each type of galaxy. And from there concludes that the universe is static, finite (positively curved), with a radius of 2.7*10^10 parsecs containing 3.5*10^15 normal galaxies.

1929 Hubble & Humason gets 558 km/s/Mpc. (This actually gives an age for the universe of less than half the age of the Earth, but that isn’t realised for a while).

1931 Oort puts error bars on the Hubble constant, errors are of the rough order of ±50%.

Oort’s graph.

1933 Zwicky supports Hubble against Oort, saying that use of the Hubble constant can “up to now predict the redshift in every case up to a few percent, even for distances that were greater by up to thirty times than the ones originally considered.” Zwicky uses galaxy clusters rather than individual galaxies to calculate the constant.

Zwicky’s graph.

1939 Gamow vs Jeans. Jeans says that the calculation by Hubble is wrong, that the Hubble constant has to be higher to prevent instability. Gamow supports Hubble. (Jeans’ correction is in the wrong direction).

1948 Bondi. Quotes a value of 101 miles per sec. per million light years for the Hubble constant. That’s 530 km/s/Mpc. In agreement with Hubble (1929).

(By 1948, still nobody had noticed that the age of the Earth is more than twice the age of the universe).

1961 Jagjit Singh in “Modern Cosmology” quotes a value of 19 miles per sec. per million light years for the Hubble constant. That’s 100 km/s/Mpc.

Singh’s graph.

To be continued.
(I still haven’t covered controversies due to: calculation using the brightest galaxy in a cluster, the realisation that Cepheids come in two types, the ages of cooling white dwarfs exceed the age of the universe, how the discovery of dark matter made the problem much worse, the final solution from the discovery of dark energy, COBE, WMAP and Planck).

(I only just noticed, ALL early calculations of the Hubble constant relied heavily on the Virgo cluster of galaxies. This gives ratshit results because the great attractor is aligned with this cluster, and is not too far off in direction from the other big nearby cluster – the Fornax cluster).

(continued)

(By 1948, still nobody had noticed that the age of the Earth is more than twice the age of the universe).

1954 Harold Weaver. It is realised that the distance measured by Cepheids is wildly wrong. The distance to the centre of the Milky Way is 8.8 kiloparsecs, but if Cepheids had been used then the calculated result would have been 3.8 kiloparsecs. (This correction to Cepheid distances has flow-on effects into the Hubble constant).

1956 Sandage and Ryle, independently, Ryle used radio astronomy, but in the same issue of Scientific American. They found that the Hubble constant increased with distance. (Later shown to be false. Not only had they not gone far enough out to show any deviation from a constant value but they also got the sign of the deviation wrong, because of dark energy it decreses with distance).

1956 Jesse L Greenstein. Calculation of the cooling rates of white dwarfs. Some white dwarfs are at least 8 billion years old (This makes them a lot older than the maximum age of the universe from the then accepted value of the Hubble constant).

1958 Sandage. The final realisation that there are two types of Cepheids. One type oscillates twice as fast as the other. In addition, it has been found that what Hubble originally identified as the brightest stars is his distant galaxies are not stars at all, but HII regions. The overall result is a correction of the Hubble constant down to 75 km/s/Mpc and an overall maximum age of the universe of 13 billion years give or take a factor of two. (Finally someone got it right, there is a huge difference between the original 558 km/s/Mpc and the corrected value).

1961 Jagjit Singh in “Modern Cosmology” quotes a value of 19 miles per sec. per million light years for the Hubble constant. That’s 100 km/s/Mpc.

1961 Schmidt-Kaler. “Recently there has been much that the age of the Galaxy derived from the evolution of stars and elements might be greater than the age of the universe derived from curent cosmological theory”. We obtain for NGC 188, the galaxy’s oldest galactic cluster, an age of 11 billion years instead of Sandage’s 16 billion years. The age of the Galaxy is given as 13.2±1 billion years and elsewhere as 14.0±1.5 billion years. “Sandage has given H_0 as 75±25 km/s/Mpc based on the galactic novae.” I get, using supergiant stars, H_0 =90±30 km/s/Mpc. (The analysis is slightly flawed, it fails to accept Gamow’s discovery in 1948 that most of the universe’s helium was produced in the Big Bang, so the ages would be slightly too high).

C1970 Quasars are finally accepted as being very distant objects, whose enormous speed is due to the expansion of the universe. But at the same time it was found that quasar luminosity is so unpredictable that they unfortunately could not be used for evaluation of the Hubble constant. Some astronomers are still clinging to the belief that Hubble’s measurement of the Hubble constant was correct.

(When I talked of furore / vigorous debate earlier, I was referring primarily to the tension between the age of the universe from the measured Hubble constant and the age of the oldest stars. This tension began before 1956 (I still need a timeline for radiometric calculation of the Earth’s age), and continued on until it was mostly solved in 1998 with the discovery of dark energy. Debate since then has been more muted, but still present, as seen in the title of this thread).

1985 Arnett and Bartel, separately. Determination of Hubble’s constant from Type 1a supernovae. From Arnett, Hubble’s constant is in the range of 39 to 73 km/s/Mpc with a best estimate of 59 km/s/Mpc. Frrom Bartel, Hubble’s constant is 40 to 100 km/s/Mpc with a best estimate of 65 km/s/Mpc. (These seem like big error ranges, but they show how stupid Zwicky was earlier for claiming accuracy “within a few percent”).

1980 Rubin, after discovering dark matter in 1970, has shown by 1980 that most galaxies contain six times as much dark matter as ordinary matter. (This throws a real spanner in the works because with the Friedmann–Lemaître equation this reduces the age of the universe by more than a billion years, creating conflict with the ages of the oldest stars).

1985 Arnett and Bartel, separately. Determination of Hubble’s constant from Type 1a supernovae. From Arnett, Hubble’s constant is in the range of 39 to 73 km/s/Mpc with a best estimate of 59 km/s/Mpc. From Bartel, Hubble’s constant is 40 to 100 km/s/Mpc with a best estimate of 65 km/s/Mpc.

1993 Lee. First reliable use of the tip of the red giant branch (RGB) to determine the distances to a few galaxies, initially ten galaxies. This work could not have been done without the Hubble Telescope.

(Still to go, the discovery of dark energy, the Tully-Fisher relation, the COBE, WMAP and Planck satellites.)

mollwollfumble said:

… until it was mostly solved in 1998 with the discovery of dark energy.

All very interesting thanks.

But shouldn’t that be “with the hypothesis of dark energy”?

The Rev Dodgson said:

mollwollfumble said:

… until it was mostly solved in 1998 with the discovery of dark energy.

All very interesting thanks.

But shouldn’t that be “with the hypothesis of dark energy”?

There’s too much evidence for dark energy, its only a matter of time before the particle is identified.

Tau.Neutrino said:

The Rev Dodgson said:

mollwollfumble said:

… until it was mostly solved in 1998 with the discovery of dark energy.

All very interesting thanks.

But shouldn’t that be “with the hypothesis of dark energy”?

There’s too much evidence for dark energy, its only a matter of time before the particle is identified.

How can there be too much when the reality appears to be not enough?

Tau.Neutrino said:

The Rev Dodgson said:

mollwollfumble said:

… until it was mostly solved in 1998 with the discovery of dark energy.

All very interesting thanks.

But shouldn’t that be “with the hypothesis of dark energy”?

There’s too much evidence for dark energy, its only a matter of time before the particle is identified.

There’s plenty of evidence for something.

Whether that “thing” is dark energy remains to be seen.

The Rev Dodgson said:

mollwollfumble said:

… until it was mostly solved in 1998 with the discovery of dark energy.

All very interesting thanks.

But shouldn’t that be “with the hypothesis of dark energy”?

No. ‘Dark energy’ is well known and understood. It’s ‘dark matter’ that can still be called a hypothesis.

1993. Kofman. Results from the COBE spacecraft strongly suggest what is later to be known as dark energy. See chart below. Here ‘h’ is the Hubble constant with a value of 1 representing 100 km/s/Mpc. Ω is the fraction of baryonic matter plus dark matter. 1-Ω is the fraction of dark energy. The case of no dark energy Ω=1 would require either a low age for the universe of a low value for the Hubble constant, neither of which agrees with previous observations. Note the maximum value of the Hubble constant of about 80 km/s/Mpc. (Dark energy itself wasn’t officially discovered until five years later).

mollwollfumble said:

The Rev Dodgson said:

mollwollfumble said:

… until it was mostly solved in 1998 with the discovery of dark energy.

All very interesting thanks.

But shouldn’t that be “with the hypothesis of dark energy”?

No. ‘Dark energy’ is well known and understood. It’s ‘dark matter’ that can still be called a hypothesis.

1993. Kofman. Results from the COBE spacecraft strongly suggest what is later to be known as dark energy. See chart below. Here ‘h’ is the Hubble constant with a value of 1 representing 100 km/s/Mpc. Ω is the fraction of baryonic matter plus dark matter. 1-Ω is the fraction of dark energy. The case of no dark energy Ω=1 would require either a low age for the universe of a low value for the Hubble constant, neither of which agrees with previous observations. Note the maximum value of the Hubble constant of about 80 km/s/Mpc. (Dark energy itself wasn’t officially discovered until five years later).

1998. Branch. This was the year in which dark energy was discovered but, just before dark energy, this paper had appeared on the measurement of the Hubble constant using Cepheids and Type 1a supernovae, following on from Arnett and Bartell mentioned above. The Hubble constant is in the range 54 to 67 km/s/Mpc or, being more lax, 60±10 km/s/Mpc.

2003. First year data from the Wilkinson Microwave Anisotropy Probe (WMAP). The Hubble constant best fit is 72±5 km/s/Mpc. With further external data this is improved to the range 68 to 75 km/s/Mpc. (Notice how this is remarkably close to Sandage’s value of 75 km/s/Mpc from way back in the year 1958).

2012. Data from nine years of operation of WMAP. The Hubble constant best fit is 70.0±2.2 km/s/Mpc. With further external data, including Baryon Acoustic Oscillation, this is improved to the range 69.32±0.80 km/s/Mpc.

2013. First data release from operation of the Planck spacecraft. The Hubble best fit is 67.4±1.4 km/s/Mpc. With further external data this is improved to the range 67.80±0.77 km/s/Mpc.

2018. Final data release from Planck, https://en.wikipedia.org/wiki/Planck_(spacecraft) . The Hubble best fit with further external data from five separate independent sources is 67.66±0.0.42 km/s/Mpc. This corresponjds to an age of the universe of 13.787±0.020 billion years.

Summary.

• The “constant” in the compound noun “Hubble constant” refers to constant at the present time rather than constant since the big bang. In practical terms it means constant out to a red shift of 0.3.
• The first measurement of the Hubble constant is in 1929, or thereabouts. But the value is out by a massive factor of 8, giving an impossibly small age for the universe. Only Oort realises how huge the error margin is.
• In 1956, it is found that some stars are older than the age of the universe. This disagreement between the two ways of measuring the age of the universe causes quite a ruckus, and persisted until solved by the discovery of dark energy in 1998.
• The first even remotely reliable measurement of the Hubble constant was by Sandage in 1958.
• The discovery of dark energy by Rubin in 1970 makes the problem that some stars are older than the age of the universe much worse.
• The first time anybody ever did a reliable calculation of the error bars on the measurement of the Hubble constant was in 1998. Before then, the error bars were either way too small (eg. Hubble) or way too large (eg. Sandage).

Now, back to the original post for this thread, which is about the use of the Tully-Fisher relationship in measuring the Hubble constamt.

From wikipedia, the Tully–Fisher relation is an empirical relationship between the intrinsic luminosity of a spiral galaxy and its rotation velocity. The rotation velocity is inferred from emission line width. This relation was first published in 1977. This relationship has no theoretical justification and is very inaccurate. The relation a manifestation of the connection between visible and dark matter mass, which is a random function of how a galaxy forms. The following graph illustrates the inaccuracy of the Tully-Fisher relation.

2001. Wendy L Freedman. “Final Results from the Hubble Space Telescope Key Project to Measure the Hubble Constant”. We find values in km/s/Mpc of 71±8 for Type Ia supernovae, 71±10 for Tully-Fisher relation, 70±10 for glaxy surface brightness fluctuations, 72±16 for Type 2 supernovae, 82±15 for “fundamental plane”. Here “fundamental plane” is an extension of the Tully-Fisher relation to elliptical galaxies. (Although excellent work, look at the bottom part of the chart below, the error on the Hubble constant from Tully-Fisher is more like ±30 than ±10).

2002. Arp. On the basis of anomalous distances from Cepheids and the Tully-Fisher relation, Arp suggests a Hubble constant near 55 km/s/Mpc. This is not good work. Arp makes no attempt to quantify the accuracy of the Tully-Fisher relationship.

The paper in the OP is clearly a descendent of Arp. Totally ignorable.