The other Great Debate (on gamma ray bursts, 1995)

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The other Great Debate (on gamma ray bursts, 1995)

Post by Ann » Sun Apr 26, 2020 2:01 pm

This year is the 100th anniversary of the Great Debate between Harlow Shapley and Heber Curtis about whether the Milky Way is all there is, or if the "spiral nebulae" are other "island universes", galaxies like our own.

The debate can be summarized like this:

Summary Shapley Curtis debate.png
The Great Debate Shapley Curtis.png

















As you can see, the Great Debate between Shapley and Curtis can be summed up in a relatively few words. I think, although I may certainly be wrong, that not very many memorable arguments were put forth by either debater.

(Correction, though: Galaxies are of course not separate universes from the Milky Way, just separate and independent large congregations of stars and dust in our shared Universe. And it may not be perfectly correct to say that Shapley won the debate, but he didn't lose his standing in the astronomical community because of it. By the way, the pictures are from https://slideplayer.com/slide/7011534/.)





















In 1995, in order to celebrate the 75th anniversary of the Shapley-Curtis debate, there was another absolutely fascinating debate which again involved the scale of the Universe. The debate hinged on the following question, Do gamma ray bursts originate in deep space or are they local phenomena?

It was known at the time that gamma ray bursts have an isotropic distribution all over the sky, but extremely little else was known about them. It was clear that if the GRBs were nearby, they were not very powerful, but if they were very far away, they had to be incredibly energetic.


The astronomers who debated the nature of and distance to the gamma ray bursts were Don Lamb and Bohdan Paczyński. Lamb argued that the gamma ray bursts had to be local, because if they were far away, they had to be more energetic than our understanding of the laws of physics could tolerate.

Lamb proposed that the progenitors of the gamma ray bursts were located in the outer parts of a very large halo of the Milky Way. A very large halo of the Milky Way will appear to be centered on the Earth, whereas a more conventionally-sized halo (like the one that contains the globular clusters of out galaxy) will make the objects in it appear to be concentrated in one part of it from our point of view.

This image from Chandra shows the Milky Way to have an extremely large gaseous halo, so in principle, Lamb's hypothesis might have been correct. But it remains to be explained why all the gamma ray bursting objects would be located in the outer parts of our galaxy's halo and hardly anywhere else.


Bohdan Paczyński argued that the gamma ray bursts originated very far way, because, as he put it, only two things have a perfect isotropic distribution across the sky, nearby stars and distant radio galaxies. All other objects favor a specific location in the sky.

Paczyński rejected the proposition that the gamma ray bursts were as close as the nearby stars. If they are so close, he argued, why haven't we caught one in the act already, in view of the fact that they seem to be so relatively common?


Paczyński also objected to the idea that practically all the gamma ray bursters would be located in the outer regions of a huge halo of the Milky Way. Why would they all emit their gamma ray flashes at a distance of perhaps 500.000 light-years from the Earth? Why isn't there a population of more nearby gamma ray bursters closer to the disk of the Milky Way, which would give rise to an anisotropic distribution of gamma ray bursts in the sky as seen from the Earth?










Also, argued Paczyński, if there is a population of gamma-ray bursting objects in the outer halo of the Milky Way, shouldn't we see an excess of fainter gamma ray bursts in the direction of Andromeda, due to a population of gamma-ray bursting objects in the outer halo of Andromeda?

Because of all this, Paczyński argued that the gamma rays must originate very far away in deep space, likely billions of light years away. We now know that Paczyński was right. Read about gamma rays bursts here.

Astronomy Magazine published the speeches that Don Lamb's and Bohdan Paczyński's gave during their great debate, and I was blown away by the brilliance of Paczyński's arguments.

It was a fun read back in 1995! :D

Ann
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Last edited by Ann on Sun Apr 26, 2020 2:12 pm, edited 1 time in total.
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Re: The other Great Debate (on gamma ray bursts, 1995)

Post by Chris Peterson » Sun Apr 26, 2020 2:05 pm

Ann wrote:
Sun Apr 26, 2020 2:01 pm
And it may not be perfectly correct to say that Shapley won the debate, but he didn't lose his standing in the astronomical community because of it.
Scientists never lose standing in their communities because they are wrong. They only lose standing in the rare cases where they are convincingly demonstrated wrong and refuse to admit it. That's rare, but does occasionally happen.
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Re: The other Great Debate (on gamma ray bursts, 1995)

Post by Ann » Sun Apr 26, 2020 2:14 pm

Chris Peterson wrote:
Sun Apr 26, 2020 2:05 pm
Ann wrote:
Sun Apr 26, 2020 2:01 pm
And it may not be perfectly correct to say that Shapley won the debate, but he didn't lose his standing in the astronomical community because of it.
Scientists never lose standing in their communities because they are wrong. They only lose standing in the rare cases where they are convincingly demonstrated wrong and refuse to admit it. That's rare, but does occasionally happen.
Point taken, but as to Shapley, he may have gained standing, at least in the short term, because of the Great Debate.

Ann
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Re: The other Great Debate (on gamma ray bursts, 1995)

Post by BDanielMayfield » Mon Apr 27, 2020 5:19 pm

Chris Peterson wrote:
Sun Apr 26, 2020 2:05 pm
Scientists never lose standing in their communities because they are wrong.
Careful Chris. That assertion, if taken out of context, could backfire. Science deniers would love it.

To provide context:
They only lose standing in the rare cases where they are convincingly demonstrated wrong and refuse to admit it. That's rare, but does occasionally happen.
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Re: The other Great Debate (on gamma ray bursts, 1995)

Post by Chris Peterson » Mon Apr 27, 2020 5:34 pm

BDanielMayfield wrote:
Mon Apr 27, 2020 5:19 pm
Chris Peterson wrote:
Sun Apr 26, 2020 2:05 pm
Scientists never lose standing in their communities because they are wrong.
Careful Chris. That assertion, if taken out of context, could backfire. Science deniers would love it.

To provide context:
They only lose standing in the rare cases where they are convincingly demonstrated wrong and refuse to admit it. That's rare, but does occasionally happen.
But it's true. It's not an argument that science is always right, only that scientists don't lose respect when their theories are proven wrong. Science deniers are already royally screwed up... there is nothing they won't bend to support their delusions.
Chris

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Re: The other Great Debate (on gamma ray bursts, 1995)

Post by neufer » Mon Apr 27, 2020 6:00 pm

Chris Peterson wrote:
Mon Apr 27, 2020 5:34 pm
BDanielMayfield wrote:
Mon Apr 27, 2020 5:19 pm
Chris Peterson wrote:
Sun Apr 26, 2020 2:05 pm

Scientists never lose standing in their communities because they are wrong.
Careful Chris. That assertion, if taken out of context, could backfire. Science deniers would love it.
But it's true. It's not an argument that science is always right, only that scientists don't lose respect when their theories are proven wrong. Science deniers are already royally screwed up... there is nothing they won't bend to support their delusions.
Art Neuendorffer

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Re: The other Great Debate (on gamma ray bursts, 1995)

Post by Ann » Mon Apr 27, 2020 6:32 pm

Chris Peterson wrote:
Sun Apr 26, 2020 2:05 pm
Ann wrote:
Sun Apr 26, 2020 2:01 pm
And it may not be perfectly correct to say that Shapley won the debate, but he didn't lose his standing in the astronomical community because of it.
Scientists never lose standing in their communities because they are wrong. They only lose standing in the rare cases where they are convincingly demonstrated wrong and refuse to admit it. That's rare, but does occasionally happen.
One more thing, Chris. After reading the written excerpts of the speeches given by Don Lamb and Bohdan Paczyński on the topic of gamma ray bursts, I was extremely impressed by Paczyński, and I felt sure that his arguments were correct. At the same time, I could see Don Lamb's point of view. He expressed himself well, and he just worried about the tremendous energies involved if the gamma ray bursts were at cosmological distances. (Back then it was assumed that whatever objects emitted gamma ray bursts did so all over their surfaces, which seemed to make their energy levels impossibly high. Now the consensus is that gamma ray bursts are emitted in jets, which brings their total energy levels down a peg.) In short, even though it turned out that Don Lamb had been wrong, his arguments still struck me as scientifically viable.

But I don't understand Harlow Shapley's arguments. The Milky Way is all there is, because - well, because otherwise the Universe is too big? Admittedly, back in 1920 extremely few people imagined that the Universe stretched far beyond the Milky Way. Harlow Shapley was influenced by the ideas of his times, and a too-vast Universe was not a part of those ideas. But shouldn't a scientist be prepared to consider ideas that are not part of, well, public opinion? Particularly if he is taking part in a debate on just those ideas?

That's what bothers me about Harlow Shapley's position. I don't see why he would argue that the Milky Way was all there was. His position doesn't strike me as a scientist's.

Ann
Last edited by Ann on Tue Apr 28, 2020 5:16 am, edited 1 time in total.
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Re: The other Great Debate (on gamma ray bursts, 1995)

Post by Chris Peterson » Mon Apr 27, 2020 7:18 pm

Ann wrote:
Mon Apr 27, 2020 6:32 pm
Chris Peterson wrote:
Sun Apr 26, 2020 2:05 pm
Ann wrote:
Sun Apr 26, 2020 2:01 pm
And it may not be perfectly correct to say that Shapley won the debate, but he didn't lose his standing in the astronomical community because of it.
Scientists never lose standing in their communities because they are wrong. They only lose standing in the rare cases where they are convincingly demonstrated wrong and refuse to admit it. That's rare, but does occasionally happen.
One more thing, Chris. After reading the written excerpts of the speeches given by Don Lamb and Bohdan Paczyński on the topic of gamma ray bursts, I was extremely impressed by Paczyński, and I felt sure that his arguments were correct. At the same time, I could see Don Lamb's point of view. He expressed himself well, and he just worried about the tremendous energies involved if the gamma ray bursts were at cosmological distances. In short, even though it turned out that Don Lamb had been wrong, his arguments still struck me as scientifically viable.

But I don't understand Harlow Shapley's arguments. The Milky Way is all there is, because - well, because otherwise the Universe is too big? Admittedly, back in 1920 extremely few people imagined that the Universe stretched far beyond the Milky Way. Harlow Shapley was influenced by the ideas of his times, and a too-vast Universe was not a part of those ideas. But shouldn't a scientist be prepared to consider ideas that are not part of, well, public opinion? Particularly if he is taking part in a debate on just those ideas?

That's what bothers me about Harlow Shapley's position. I don't see why he would argue that the Milky Way was all there was. His position doesn't strike me as a scientist's.
Do you think Shapley refused to consider the possibility that Curtis was right? All scientists are influenced by the ideas of their times and by their individual biases. But most scientists- even those with strongly held opinions about specific theories- do not label as impossible or ridiculous other theories. They are open to having their minds changed. Within five years of the Great Debate, Shapely accepted the evidence of Hubble and the true nature and distance of galaxies.

And, of course, it was a debate. The entire point was for each participant to defend opposing propositions.
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Re: The other Great Debate (on gamma ray bursts, 1995)

Post by Ann » Mon Apr 27, 2020 8:31 pm

Chris Peterson wrote:
Mon Apr 27, 2020 7:18 pm
Ann wrote:
Mon Apr 27, 2020 6:32 pm
Chris Peterson wrote:
Sun Apr 26, 2020 2:05 pm


Scientists never lose standing in their communities because they are wrong. They only lose standing in the rare cases where they are convincingly demonstrated wrong and refuse to admit it. That's rare, but does occasionally happen.
One more thing, Chris. After reading the written excerpts of the speeches given by Don Lamb and Bohdan Paczyński on the topic of gamma ray bursts, I was extremely impressed by Paczyński, and I felt sure that his arguments were correct. At the same time, I could see Don Lamb's point of view. He expressed himself well, and he just worried about the tremendous energies involved if the gamma ray bursts were at cosmological distances. In short, even though it turned out that Don Lamb had been wrong, his arguments still struck me as scientifically viable.

But I don't understand Harlow Shapley's arguments. The Milky Way is all there is, because - well, because otherwise the Universe is too big? Admittedly, back in 1920 extremely few people imagined that the Universe stretched far beyond the Milky Way. Harlow Shapley was influenced by the ideas of his times, and a too-vast Universe was not a part of those ideas. But shouldn't a scientist be prepared to consider ideas that are not part of, well, public opinion? Particularly if he is taking part in a debate on just those ideas?

That's what bothers me about Harlow Shapley's position. I don't see why he would argue that the Milky Way was all there was. His position doesn't strike me as a scientist's.
Do you think Shapley refused to consider the possibility that Curtis was right? All scientists are influenced by the ideas of their times and by their individual biases. But most scientists- even those with strongly held opinions about specific theories- do not label as impossible or ridiculous other theories. They are open to having their minds changed. Within five years of the Great Debate, Shapely accepted the evidence of Hubble and the true nature and distance of galaxies.

And, of course, it was a debate. The entire point was for each participant to defend opposing propositions.
And as usual, Chris, I can see your point. :wink:

But I still don't understand that Heber Curtis, who was the one who was right in the Great Debate, has become so forgotten. I realize that Shapley had a longer and more varied life than Curtis, and he was much more influential than Curtis in his time, both inside and outside the field of astronomy. Still, I find the lack of interest in Curtis hard to swallow. Compare the Wikipedia texts written about these two men, and compare what is said about the Great Debate in the Wikipedia article about Shapley and what is said in the stub about Heber Curtis!

Ann
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Re: The other Great Debate (on gamma ray bursts, 1995)

Post by BDanielMayfield » Mon Apr 27, 2020 9:12 pm

Chris Peterson wrote:
Mon Apr 27, 2020 5:34 pm
BDanielMayfield wrote:
Mon Apr 27, 2020 5:19 pm
Chris Peterson wrote:
Sun Apr 26, 2020 2:05 pm
Scientists never lose standing in their communities because they are wrong.
Careful Chris. That assertion, if taken out of context, could backfire. Science deniers would love it.

To provide context:
They only lose standing in the rare cases where they are convincingly demonstrated wrong and refuse to admit it. That's rare, but does occasionally happen.
But it's true. It's not an argument that science is always right, only that scientists don't lose respect when their theories are proven wrong.
Well explained.
Science deniers are already royally screwed up... there is nothing they won't bend to support their delusions.
I agree, science deniers use flawed reasoning to defend untenable positions. Cases in point in my opinion are Flat Earthers, AGW Deniers and Young Earth Creationists.

But then many probably label me as a science denier too because I don't agree with the whole body of current consensus science viewpoints. Specifically, I don't go along with accidental cosmology nor with macro evolution. If one is unwilling to accept unproven but commonly taught beliefs about the past, then is one automatically also a "science denier"? I don't think so. The label fits when the science being doubled is irrefutable, and not when it rests on unproven conjecture, no matter how popular it has become.

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Re: The other Great Debate (on gamma ray bursts, 1995)

Post by Chris Peterson » Mon Apr 27, 2020 9:51 pm

BDanielMayfield wrote:
Mon Apr 27, 2020 9:12 pm
Chris Peterson wrote:
Mon Apr 27, 2020 5:34 pm
BDanielMayfield wrote:
Mon Apr 27, 2020 5:19 pm

Careful Chris. That assertion, if taken out of context, could backfire. Science deniers would love it.

To provide context:
But it's true. It's not an argument that science is always right, only that scientists don't lose respect when their theories are proven wrong.
Well explained.
Science deniers are already royally screwed up... there is nothing they won't bend to support their delusions.
I agree, science deniers use flawed reasoning to defend untenable positions. Cases in point in my opinion are Flat Earthers, AGW Deniers and Young Earth Creationists.

But then many probably label me as a science denier too because I don't agree with the whole body of current consensus science viewpoints. Specifically, I don't go along with accidental cosmology nor with macro evolution. If one is unwilling to accept unproven but commonly taught beliefs about the past, then is one automatically also a "science denier"? I don't think so. The label fits when the science being doubled is irrefutable, and not when it rests on unproven conjecture, no matter how popular it has become.

Bruce
Science deniers go well beyond using flawed reasoning. Science denialism is characterized by becoming more entrenched in a faulty belief system as more evidence is provided against it.

There is no scientific concept of "accidental cosmology". There are just various theories of cosmology. None offer an original cause, nor seek to.

There is no such thing as "macro evolution". There is just the observation of evolution, which is explained by a number of well supported theories.
Chris

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