Source: Marcel Drechsler 1, Xavier Strottner 2, Yann Sainty 3, Robert A. Fesen 4, Stefan Kimeswenger 5, 6, J. Michael Shull 7, Bray Falls 8, Christophe Vergnes 9, Nicolas Martino 9, Sean Walker 10
Re: APOD: M31: The Andromeda Galaxy (2024 Sep 08)
Posted: Sun Sep 08, 2024 7:02 am
by Ann
Yes, that's a nice portrait of the most-photographed non-Milky Way galaxy of them all!
But, as is the case in all beauty contests, it is important to show both beautiful people and impressive galaxies in the most flattering light and from the most flattering angles. When it comes to the Andromeda galaxy, most pictures show it just as it looks in the APOD, stretching from lower left to upper right so that its shape looks like Hubble's Law:
Apparently we don't like seeing Andromeda "leaning over" the way it does in the T. Rector/B. Wolpa image, because you can't believe how hard it is to find "smaller than 500 KB" images where Andromeda is positioned like this! It's like seeing Fred Astaire dancing in the ceiling - it's just wrong!
Click to play embedded YouTube video.
As for the T. Rector/B. Wolpa picture of Andromeda, I'm critical of the colors of it. Note the extremely red colors of many of the stars, the red color of one of the dust lanes, and the general lack of color elsewhere.
But there is one thing that I really like about T. Rector/B. Wolpa image, and that is the brilliance of the central parts of Andromeda and the faintness of the outer parts. Because that is the way it is with Andromeda.
Look at Achint Thomas' image of Andromeda again. You can see that Andromeda is "leaning the right way", but NGC 205, the elongated satellite galaxy, is located to the lower left of the center of Andromeda and not at the upper right of it. So in this image, north is up, but east is to the right. Note that you can just make out NGC 206, the largest and brightest association of young stars in Andromeda, at lower right.
One lesson you can really draw from Achint Thomas' image is that Andromeda is a yellow galaxy. It is very, very massive, too, because all galaxies with a large and very bright yellow population of stars are always massive.
APOD Robot wrote:
In only about 5 billion years, the Andromeda galaxy may be even easier to see -- as it will likely span the entire night sky -- just before it merges with, or passes right by, our Milky Way Galaxy.
The Andromeda galaxy will become easier to see as it comes closer? I'm not sure about that. The surface brightness of Andromeda will not grow brighter as the galaxy approaches, and instead the stars will become more spread out. Seeing Andromeda when it looms very large in the sky will probably be like spotting the light of the Milky Way in the sky. Impressive, but not all that impressive.
We're certainly not short of Andromeda images, but to newcomers I like to show this one and say "Notice the myriads of background stars, well, they're not! It's the GALAXY that's far in the background!". Gosh is this object huge... (and hugely beautiful!)
(David Dayag)
Re: APOD: M31: The Andromeda Galaxy (2024 Sep 08)
Posted: Mon Sep 09, 2024 3:48 am
by shaileshs
I checked the link for "passes right" (https://www.science.org/content/article ... eda-galaxy), I'm glad many scientists openly said we don't know many things and so it's impossible to simulate and predict any deterministic ways. I absolutely agree. I think in 20-50 years, whatever we think we "know" so far will get upended. Many many assumptions and so predictions will absolutely change. Currently, we are just fooling ourselves if we say we know a lot about how universe works and what will happen in future.
Re: APOD: M31: The Andromeda Galaxy (2024 Sep 08)
Posted: Mon Sep 09, 2024 4:27 am
by Chris Peterson
shaileshs wrote: ↑Mon Sep 09, 2024 3:48 am
I checked the link for "passes right" (https://www.science.org/content/article ... eda-galaxy), I'm glad many scientists openly said we don't know many things and so it's impossible to simulate and predict any deterministic ways. I absolutely agree. I think in 20-50 years, whatever we think we "know" so far will get upended. Many many assumptions and so predictions will absolutely change. Currently, we are just fooling ourselves if we say we know a lot about how universe works and what will happen in future.
shaileshs wrote: ↑Mon Sep 09, 2024 3:48 am
I checked the link for "passes right" (https://www.science.org/content/article ... eda-galaxy), I'm glad many scientists openly said we don't know many things and so it's impossible to simulate and predict any deterministic ways. I absolutely agree. I think in 20-50 years, whatever we think we "know" so far will get upended. Many many assumptions and so predictions will absolutely change. Currently, we are just fooling ourselves if we say we know a lot about how universe works and what will happen in future.
I predict you are wrong.
Chris, i respect your knowledge and you are entitled to any opinion (including your above prediction). I'm no Aristotle or Einstein but they both seem to be in agreement with me. Their own quotes = Aristotle ("The more you know, more you know that you don't know") and Einstein ("What we don't know is much more than what we know")
And, I'll also add this - As @Sadhguru says, "i don't know" is VERY POWERFUL. It's better to accept we don't know. Because the moment we say we know, the quest to find and experience the truth ends. Just my personal opinion.
shaileshs wrote: ↑Mon Sep 09, 2024 3:48 am
I checked the link for "passes right" (https://www.science.org/content/article ... eda-galaxy), I'm glad many scientists openly said we don't know many things and so it's impossible to simulate and predict any deterministic ways. I absolutely agree. I think in 20-50 years, whatever we think we "know" so far will get upended. Many many assumptions and so predictions will absolutely change. Currently, we are just fooling ourselves if we say we know a lot about how universe works and what will happen in future.
I predict you are wrong.
Chris, i respect your knowledge and you are entitled to any opinion (including your above prediction). I'm no Aristotle or Einstein but they both seem to be in agreement with me. Their own quotes = Aristotle ("The more you know, more you know that you don't know") and Einstein ("What we don't know is much more than what we know")
I think we know almost everything. Just a few holes left, and nothing that we currently know is going to be overturned... just tweaked as we home on the final truths. The Universe is simple. Stunningly simple, and governed by just a handful of rules. It makes me think of Conway's Game of Life. A simple set of easy to understand rules which produce infinite complexity in the form of emergent properties.
Chris, i respect your knowledge and you are entitled to any opinion (including your above prediction). I'm no Aristotle or Einstein but they both seem to be in agreement with me. Their own quotes = Aristotle ("The more you know, more you know that you don't know") and Einstein ("What we don't know is much more than what we know")
I think we know almost everything. Just a few holes left, and nothing that we currently know is going to be overturned... just tweaked as we home on the final truths. The Universe is simple. Stunningly simple, and governed by just a handful of rules. It makes me think of Conway's Game of Life. A simple set of easy to understand rules which produce infinite complexity in the form of emergent properties.
In the past (400 to 2 years in past), I'm sure people felt same as what you are feeling now. Someone thought they knew Earth was flat. Someone thought they knew Earth was center of universe. And as recently as 30 yrs ago, before someone "discovered" dark energy and the impact it has, people thought they knew the universe would collapse in big crunch with so much gravity. Even till 2 years back (until James Webb), people thought they KNEW there couldn't be big galaxies in 300 million light years after "big bang". And now James Webb is finding those galaxies and proving those people wrong.
And ALL those people who thought they KNEW were proved wrong. With latest developments, data, science and discoveries/inventions.
Same will be case in next 50-100-400 years. Data, discoveries will happen. What people think they knew in 2024 will be proven wrong. People may find universe has been around not just for 13.7 billion years but maybe since 100s of billions years.. Who knows 500 years from now they'll say Earth (planets) was born (could form) before Sun (star)..
Nobody knows. History has shown it in the past, history will repeat.
It's just that you and me won't be around when that happens (whether history proves you or me wrong)..
Chris, i respect your knowledge and you are entitled to any opinion (including your above prediction). I'm no Aristotle or Einstein but they both seem to be in agreement with me. Their own quotes = Aristotle ("The more you know, more you know that you don't know") and Einstein ("What we don't know is much more than what we know")
I think we know almost everything. Just a few holes left, and nothing that we currently know is going to be overturned... just tweaked as we home on the final truths. The Universe is simple. Stunningly simple, and governed by just a handful of rules. It makes me think of Conway's Game of Life. A simple set of easy to understand rules which produce infinite complexity in the form of emergent properties.
In the past (300 to 30 years in past), I'm sure people felt same as what you are feeling now. Someone thought they knew Earth was flat. Someone thought they knew Earth was center of universe. And as recently as 30 yrs ago, before someone "discovered" dark energy and the impact it has, people thought they knew the universe would collapse in big crunch with so much gravity.
And ALL those people who thought they KNEW were proved wrong. With latest developments, data, science and discoveries/inventions.
Same will be case in next 50-100-400 years. Data, discoveries will happen. What people think they knew in 2024 will be proven wrong. History has shown it in the past, history will repeat. It's just that you and me won't be around when that happens (whether history proves you or me wrong)..
Modern science is perhaps a century old. And in that time, no major fundamental theories have been thrown out and replaced. Only modified. Dark energy is certainly in that category. We don't prove major things wrong anymore. Because we've mostly figured them out. I have little doubt that in a century, probably much less, we'll know all the laws of nature.
I think we know almost everything. Just a few holes left, and nothing that we currently know is going to be overturned... just tweaked as we home on the final truths. The Universe is simple. Stunningly simple, and governed by just a handful of rules. It makes me think of Conway's Game of Life. A simple set of easy to understand rules which produce infinite complexity in the form of emergent properties.
In the past (300 to 30 years in past), I'm sure people felt same as what you are feeling now. Someone thought they knew Earth was flat. Someone thought they knew Earth was center of universe. And as recently as 30 yrs ago, before someone "discovered" dark energy and the impact it has, people thought they knew the universe would collapse in big crunch with so much gravity.
And ALL those people who thought they KNEW were proved wrong. With latest developments, data, science and discoveries/inventions.
Same will be case in next 50-100-400 years. Data, discoveries will happen. What people think they knew in 2024 will be proven wrong. History has shown it in the past, history will repeat. It's just that you and me won't be around when that happens (whether history proves you or me wrong)..
Modern science is perhaps a century old. And in that time, no major fundamental theories have been thrown out and replaced. Only modified. Dark energy is certainly in that category. We don't prove major things wrong anymore. Because we've mostly figured them out. I have little doubt that in a century, probably much less, we'll know all the laws of nature.
Let's compare notes in 50 years and we'll see...
It depends on what you mean by "almost everything". There are lots of things we do not know. There is currently no analytic solution to the three body problem in either Newtonian Dynamics or General Relativity, and as for many-body problems, we can simulate using computers, but these break down. We do not know what actually happens inside stars. We know there is no formula for the roots of the general quintic equation in surds, but clearly the roots must depend on the coefficients. We have no idea how life or intelligence arise from apparently inert matter. Modelling the atmosphere and predicting weather is extremely difficult. 'Dark energy' and 'dark matter' are hypotheses to explain observations of the expansion of the Universe and the orbital velocities of stars in galaxies, but both are proving very difficult to capture experimentally.
As Newton claimed, he considered that "the great ocean of truth lay all undiscovered before me", and Feynman claimed that anyone who claims to understand quantum mechanics does not understand quantum mechanics. And, of course, we need to remember that these mathematical models of 'reality' are just that, models, not reality. Mathematics is beautiful, but it is an abstraction from our observations of reality, and we then interpret the mathematical models to make predictions. Dirac's discovery of anti-matter from equations being one of the successes, but jut because something physical is predicted by a mathematical model does not make it true.
I lack Mr Peterson's confidence that we know 'almost everything' already, although as I might just still be around in 50 years (assuming our politicians are able to avoid armageddon) I'll wait and see,
In the past (300 to 30 years in past), I'm sure people felt same as what you are feeling now. Someone thought they knew Earth was flat. Someone thought they knew Earth was center of universe. And as recently as 30 yrs ago, before someone "discovered" dark energy and the impact it has, people thought they knew the universe would collapse in big crunch with so much gravity.
And ALL those people who thought they KNEW were proved wrong. With latest developments, data, science and discoveries/inventions.
Same will be case in next 50-100-400 years. Data, discoveries will happen. What people think they knew in 2024 will be proven wrong. History has shown it in the past, history will repeat. It's just that you and me won't be around when that happens (whether history proves you or me wrong)..
Modern science is perhaps a century old. And in that time, no major fundamental theories have been thrown out and replaced. Only modified. Dark energy is certainly in that category. We don't prove major things wrong anymore. Because we've mostly figured them out. I have little doubt that in a century, probably much less, we'll know all the laws of nature.
Let's compare notes in 50 years and we'll see...
It depends on what you mean by "almost everything". There are lots of things we do not know. There is currently no analytic solution to the three body problem in either Newtonian Dynamics or General Relativity, and as for many-body problems, we can simulate using computers, but these break down. We do not know what actually happens inside stars. We know there is no formula for the roots of the general quintic equation in surds, but clearly the roots must depend on the coefficients. We have no idea how life or intelligence arise from apparently inert matter. Modelling the atmosphere and predicting weather is extremely difficult. 'Dark energy' and 'dark matter' are hypotheses to explain observations of the expansion of the Universe and the orbital velocities of stars in galaxies, but both are proving very difficult to capture experimentally.
As Newton claimed, he considered that "the great ocean of truth lay all undiscovered before me", and Feynman claimed that anyone who claims to understand quantum mechanics does not understand quantum mechanics. And, of course, we need to remember that these mathematical models of 'reality' are just that, models, not reality. Mathematics is beautiful, but it is an abstraction from our observations of reality, and we then interpret the mathematical models to make predictions. Dirac's discovery of anti-matter from equations being one of the successes, but jut because something physical is predicted by a mathematical model does not make it true.
I lack Mr Peterson's confidence that we know 'almost everything' already, although as I might just still be around in 50 years (assuming our politicians are able to avoid armageddon) I'll wait and see,
Most of the things you list are not fundamental properties of nature. They are emergent properties. Some are just math curiosities. The only things in your list that represent actual fundamental unknowns right now are the nature of dark matter and dark energy... and I have little doubt we'll figure those out in the near future.
Chris Peterson wrote: ↑Mon Sep 09, 2024 5:06 am
Modern science is perhaps a century old. And in that time, no major fundamental theories have been thrown out and replaced. Only modified. Dark energy is certainly in that category. We don't prove major things wrong anymore. Because we've mostly figured them out. I have little doubt that in a century, probably much less, we'll know all the laws of nature.
Let's compare notes in 50 years and we'll see...
It depends on what you mean by "almost everything". There are lots of things we do not know. There is currently no analytic solution to the three body problem in either Newtonian Dynamics or General Relativity, and as for many-body problems, we can simulate using computers, but these break down. We do not know what actually happens inside stars. We know there is no formula for the roots of the general quintic equation in surds, but clearly the roots must depend on the coefficients. We have no idea how life or intelligence arise from apparently inert matter. Modelling the atmosphere and predicting weather is extremely difficult. 'Dark energy' and 'dark matter' are hypotheses to explain observations of the expansion of the Universe and the orbital velocities of stars in galaxies, but both are proving very difficult to capture experimentally.
As Newton claimed, he considered that "the great ocean of truth lay all undiscovered before me", and Feynman claimed that anyone who claims to understand quantum mechanics does not understand quantum mechanics. And, of course, we need to remember that these mathematical models of 'reality' are just that, models, not reality. Mathematics is beautiful, but it is an abstraction from our observations of reality, and we then interpret the mathematical models to make predictions. Dirac's discovery of anti-matter from equations being one of the successes, but jut because something physical is predicted by a mathematical model does not make it true.
I lack Mr Peterson's confidence that we know 'almost everything' already, although as I might just still be around in 50 years (assuming our politicians are able to avoid armageddon) I'll wait and see,
Most of the things you list are not fundamental properties of nature. They are emergent properties. Some are just math curiosities. The only things in your list that represent actual fundamental unknowns right now are the nature of dark matter and dark energy... and I have little doubt we'll figure those out in the near future.
Hmm, by "math curiosities" I am guessing you include my reference to there being no solution to the general quintic using surds. This may indicate that our current notation for arithmetical functions is incomplete, which would be fundamental to every model of the physical properties of nature. Specifically, if you want to 'do' particle physics, you need to learn the algebra of group theory, and it is group theory that is used to show the insolubility of the general quintic with surds. (An excellent algebra textbook is 'Rings, Fields and Groups' by R B J T Allenby, 2nd edition, the final chapter is on Galois theory. I marked Allenby's algebra course when I was a Ph.D. student at Leeds, and he was very good at explaining things. The book is worth reading just for the style of exposition and the constant challenging of the reader to actually understand rather than merely accept what is said.). If there is something fundamental missing from our mathematical notation, then we may be unable to write down the mathematics, and hence the physics of 'dark matter' or 'dark energy'. And if there is nothing fundamental form our arithmetic notation, it may mean that we will never be able to write down the equations explaining how the. universe works.
An example: If I write "69 = LXIX", what I mean is that the number represented by decimal notation on the left side of the equals sign is the same as the number represented in Roman numerals on the right side. But decimal notation only became the dominant way of writing numbers at the time of William Shakespeare (his father used Roman numerals). The model of arithmetic presented by Roman numerals was inefficient and superseded by positional notation which allowed addition subtraction, multiplication and division to be taught relatively easily. However, much work is being done to discover whether division (i.e. divisibility by prime numbers and factorisation) is computationally more complex than multiplication. This matters for the security of the entire global financial system and is a fundamental question of the nature of numbers and arithmetic and our ability to model physical reality.
Edit - typo "quintic" for "quixotic" Cursed 'auto-correct'.
It depends on what you mean by "almost everything". There are lots of things we do not know. There is currently no analytic solution to the three body problem in either Newtonian Dynamics or General Relativity, and as for many-body problems, we can simulate using computers, but these break down. We do not know what actually happens inside stars. We know there is no formula for the roots of the general quintic equation in surds, but clearly the roots must depend on the coefficients. We have no idea how life or intelligence arise from apparently inert matter. Modelling the atmosphere and predicting weather is extremely difficult. 'Dark energy' and 'dark matter' are hypotheses to explain observations of the expansion of the Universe and the orbital velocities of stars in galaxies, but both are proving very difficult to capture experimentally.
As Newton claimed, he considered that "the great ocean of truth lay all undiscovered before me", and Feynman claimed that anyone who claims to understand quantum mechanics does not understand quantum mechanics. And, of course, we need to remember that these mathematical models of 'reality' are just that, models, not reality. Mathematics is beautiful, but it is an abstraction from our observations of reality, and we then interpret the mathematical models to make predictions. Dirac's discovery of anti-matter from equations being one of the successes, but jut because something physical is predicted by a mathematical model does not make it true.
I lack Mr Peterson's confidence that we know 'almost everything' already, although as I might just still be around in 50 years (assuming our politicians are able to avoid armageddon) I'll wait and see,
Most of the things you list are not fundamental properties of nature. They are emergent properties. Some are just math curiosities. The only things in your list that represent actual fundamental unknowns right now are the nature of dark matter and dark energy... and I have little doubt we'll figure those out in the near future.
Hmm, by "math curiosities" I am guessing you include my reference to there being no solution to the general quintic using surds. This may indicate that our current notation for arithmetical functions is incomplete, which would be fundamental to every model of the physical properties of nature. Specifically, if you want to 'do' particle physics, you need to learn the algebra of group theory, and it is group theory that is used to show the insolubility of the general quintic with surds. (An excellent algebra textbook is 'Rings, Fields and Groups' by R B J T Allenby, 2nd edition, the final chapter is on Galois theory. I marked Allenby's algebra course when I was a Ph.D. student at Leeds, and he was very good at explaining things. The book is worth reading just for the style of exposition and the constant challenging of the reader to actually understand rather than merely accept what is said.). If there is something fundamental missing from our mathematical notation, then we may be unable to write down the mathematics, and hence the physics of 'dark matter' or 'dark energy'. And if there is nothing fundamental form our arithmetic notation, it may mean that we will never be able to write down the equations explaining how the. universe works.
An example: If I write "69 = LXIX", what I mean is that the number represented by decimal notation on the left side of the equals sign is the same as the number represented in Roman numerals on the right side. But decimal notation only became the dominant way of writing numbers at the time of William Shakespeare (his father used Roman numerals). The model of arithmetic presented by Roman numerals was inefficient and superseded by positional notation which allowed addition subtraction, multiplication and division to be taught relatively easily. However, much work is being done to discover whether division (i.e. divisibility by prime numbers and factorisation) is computationally more complex than multiplication. This matters for the security of the entire global financial system and is a fundamental question of the nature of numbers and arithmetic and our ability to model physical reality.
Edit - typo "quintic" for "quixotic" Cursed 'auto-correct'.
I think you've missed my point, which is just that there aren't very many fundamental natural laws, and we appear to understand most of them.
Re: APOD: M31: The Andromeda Galaxy (2024 Sep 08)
Posted: Wed Sep 11, 2024 2:13 pm
by Eclectic Man
"I think you've missed my point, which is just that there aren't very many fundamental natural laws, and we appear to understand most of them."
Well, maybe, but how do you know "that there aren't very many fundamental natural laws", and what do you mean by "aren't very many". We don't know how many fundamental laws of nature there are, neither do we currently understand the 'laws' we claim are fundamental completely. Maybe you and I simply have different ideas about what constitutes 'fundamental' and 'understanding'.
Re: APOD: M31: The Andromeda Galaxy (2024 Sep 08)
Posted: Wed Sep 11, 2024 2:17 pm
by Chris Peterson
Eclectic Man wrote: ↑Wed Sep 11, 2024 2:13 pm
"I think you've missed my point, which is just that there aren't very many fundamental natural laws, and we appear to understand most of them."
Well, maybe, but how do you know "that there aren't very many fundamental natural laws", and what do you mean by "aren't very many". We don't know how many fundamental laws of nature there are, neither do we currently understand the 'laws' we claim are fundamental completely. Maybe you and I simply have different ideas about what constitutes 'fundamental' and 'understanding'.
Well, there doesn't seem to be a need for more than we're already aware of, which accurately describe how everything works (well enough that the remaining holes are pretty easy to see).
Re: APOD: M31: The Andromeda Galaxy (2024 Sep 08)
Posted: Wed Sep 11, 2024 8:27 pm
by AVAO
Eclectic Man wrote: ↑Tue Sep 10, 2024 8:22 pm
[...]
As Newton claimed, he considered that "the great ocean of truth lay all undiscovered before me", and Feynman claimed that anyone who claims to understand quantum mechanics does not understand quantum mechanics. And, of course, we need to remember that these mathematical models of 'reality' are just that, models, not reality. Mathematics is beautiful, but it is an abstraction from our observations of reality, and we then interpret the mathematical models to make predictions.
[...]
I think that is certainly an important point that you make.
Scientific models, based on scientific facts, are the basis of our scientific understanding of the world. The current models - including those of dark matter and dark energy - are the best we have. Future models that are more consistent with scientifically accepted facts can also displace existing or earlier models. This has not only happened a lot in the past, but will also happen in the future. Scientifically questioning existing models is also an important task for science. What makes little sense, however, is to discard existing models without models that are more scientifically appropriate. If this were to happen, we would destabilize the entire science and plunge it into permanent chaos. Existing scientific models may only be replaced by models that have been proven to be better, and this process must be carried out according to strict scientific principles.
The current models are the best we have. In this respect - and I completely agree with Chris - any further discussion makes no sense.
Eclectic Man wrote: ↑Tue Sep 10, 2024 8:22 pm
[...]
As Newton claimed, he considered that "the great ocean of truth lay all undiscovered before me", and Feynman claimed that anyone who claims to understand quantum mechanics does not understand quantum mechanics. And, of course, we need to remember that these mathematical models of 'reality' are just that, models, not reality. Mathematics is beautiful, but it is an abstraction from our observations of reality, and we then interpret the mathematical models to make predictions.
[...]
I think that is certainly an important point that you make.
Scientific models, based on scientific facts, are the basis of our scientific understanding of the world. The current models - including those of dark matter and dark energy - are the best we have. Future models that are more consistent with scientifically accepted facts can also displace existing or earlier models. This has not only happened a lot in the past, but will also happen in the future. Scientifically questioning existing models is also an important task for science. What makes little sense, however, is to discard existing models without models that are more scientifically appropriate. If this were to happen, we would destabilize the entire science and plunge it into permanent chaos. Existing scientific models may only be replaced by models that have been proven to be better, and this process must be carried out according to strict scientific principles.
The current models are the best we have. In this respect - and I completely agree with Chris - any further discussion makes no sense.
I'll leave discussions of what is "real" to philosophers. To me, if an equation or model reliably describes nature, it is as real as it needs to be. If there's some deeper "reality" I don't really care. It has been a long time since any description we have of fundamental natural law has been thrown out. We are in a time of refinement now, and I don't think that's likely to change. We know most of how things work, and I expect the last pieces will fall into place in no more than a few decades. That knowledge, combined with powerful computing, will allow us to deeply explore the actual complexity of the Universe, which is not found in its fundamental principles, but in the infinite emergent properties those principles can produce.
M31: The Andromeda Galaxy
