APOD: Illustris: A Simulation of the Universe (2023 Dec 31)

[APOD Robot]

Illustris: A Simulation of the Universe

Explanation: How did we get here? Click play, sit back, and watch. A computer simulation of the evolution of the universe provides insight into how galaxies formed and perspectives into humanity's place in the universe. The Illustris project exhausted 20 million CPU hours in 2014 following 12 billion resolution elements spanning a cube 35 million light years on a side as it evolved over 13 billion years. The simulation tracks matter into the formation of a wide variety of galaxy types. As the virtual universe evolves, some of the matter expanding with the universe soon gravitationally condenses to form filaments, galaxies, and clusters of galaxies. The featured video takes the perspective of a virtual camera circling part of this changing universe, first showing the evolution of dark matter, then hydrogen gas coded by temperature (0:45), then heavy elements such as helium and carbon (1:30), and then back to dark matter (2:07). On the lower left the time since the Big Bang is listed, while on the lower right the type of matter being shown is listed. Explosions (0:50) depict galaxy-center supermassive black holes expelling bubbles of hot gas. Interesting discrepancies between Illustris and the real universe have been studied, including why the simulation produced an overabundance of old stars.

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[Ann]

I'll leave it to those who are smarter than me to say something clever about the simulation in today's APOD.

Instead, I'll show you my favorite Illustris simulation!

Visualization of the intensity of shock waves in the cosmic gas (blue)
around collapsed dark matter structures (orange/white). Similar to a sonic boom,
the gas in these shock waves is accelerated with a jolt when impacting
cosmic filaments and galaxies.

Neat, eh? This simulation shows dark matter (orange/white) and light blue gas undergoing sonic booms (well, something similar to sonic booms) when impacting these dark matter structures. Of course you can see the cosmic filaments and voids as well.

I was going to say, "Blockhead signing off", meaning myself, and then finding a picture of a blockhead resembling me. I was utterly unsuccessful. But, as a bonus, I'll remind you of another "blockhead", a brilliant mathematician! A man as smart as can be!

A book about Leonardo Bonacci, better known as Fibonacci, a man as non-blockheaded as can be.

---

Wikipedia wrote:

Fibonacci (/ˌfɪbəˈnɑːtʃi/;[3] also US: /ˌfiːb-/,[4][5] Italian: [fiboˈnattʃi]; c. 1170 – c. 1240–50),[6] also known as Leonardo Bonacci, Leonardo of Pisa, or Leonardo Bigollo Pisano ('Leonardo the Traveller from Pisa'[7]), was an Italian mathematician from the Republic of Pisa, considered to be "the most talented Western mathematician of the Middle Ages"...

In the Fibonacci sequence, each number is the sum of the previous two numbers. Fibonacci omitted the "0" and first "1" included today and began the sequence with 1, 2, 3, ... . He carried the calculation up to the thirteenth place, the value 233, though another manuscript carries it to the next place, the value 377.[34][35] Fibonacci did not speak about the golden ratio as the limit of the ratio of consecutive numbers in this sequence.

Ann

[shaileshs]

It's great experiment and am sure lot of time, money, efforts, knowledge involved in creating this but I can't help resist the thought that maybe all this is moot with latest discoveries James Webb ? I mean, the whole thing was based on 2014, 9 years ago and tons of things have changed since then which at least have created lot of doubt into what we *thought* we knew and new question marks have come in (which is good in my opinion). I don't believe we still know how the universe began (mysterious lumps or uniform distribution.. we have no idea if galaxies formed first or dark holes, we have no idea how old is universe (how long it expanded and slowed down and expanded again), anything we don't know we seem to clump it with *dark* (matter and/or energy).. Scientists and researchers seem to be ignoring tons of things already well explained in ancient (5000-10000 years old) Indian Vedas and Puranas (including space, time, cycles of universe, multi-universes, evolution of species, calculations about cycles of universe, even string theory/vibration based basic of universe, .. etc).. It's mind boggling. I'm curious what others have to say.. Thanks in advance to everyone and Happy New Year to everyone!

[Chris Peterson]

It's great experiment and am sure lot of time, money, efforts, knowledge involved in creating this but I can't help resist the thought that maybe all this is moot with latest discoveries James Webb ? I mean, the whole thing was based on 2014, 9 years ago and tons of things have changed since then which at least have created lot of doubt into what we *thought* we knew and new question marks have come in (which is good in my opinion). I don't believe we still know how the universe began (mysterious lumps or uniform distribution.. we have no idea if galaxies formed first or dark holes, we have no idea how old is universe (how long it expanded and slowed down and expanded again), anything we don't know we seem to clump it with *dark* (matter and/or energy).. Scientists and researchers seem to be ignoring tons of things already well explained in ancient (5000-10000 years old) Indian Vedas and Puranas (including space, time, cycles of universe, multi-universes, evolution of species, calculations about cycles of universe, even string theory/vibration based basic of universe, .. etc).. It's mind boggling. I'm curious what others have to say.. Thanks in advance to everyone and Happy New Year to everyone!

The simulation isn't based on anything from 2014. The simulation is based on modeling a cosmological theory and then comparing the output to observations. For the most part, that output looks very much like what we actually observe, which lends support for the theory.

Recent observations have raised questions about the early universe... just when it was, and just how stars and galaxies were forming so early. Those observations suggest that the cosmological models may require adjustment. I think it's doubtful that they will change radically, however, given the huge amount of evidence that supports their broad accuracy.

[shaileshs]

It's great experiment and am sure lot of time, money, efforts, knowledge involved in creating this but I can't help resist the thought that maybe all this is moot with latest discoveries James Webb ? I mean, the whole thing was based on 2014, 9 years ago and tons of things have changed since then which at least have created lot of doubt into what we *thought* we knew and new question marks have come in (which is good in my opinion). I don't believe we still know how the universe began (mysterious lumps or uniform distribution.. we have no idea if galaxies formed first or dark holes, we have no idea how old is universe (how long it expanded and slowed down and expanded again), anything we don't know we seem to clump it with *dark* (matter and/or energy).. Scientists and researchers seem to be ignoring tons of things already well explained in ancient (5000-10000 years old) Indian Vedas and Puranas (including space, time, cycles of universe, multi-universes, evolution of species, calculations about cycles of universe, even string theory/vibration based basic of universe, .. etc).. It's mind boggling. I'm curious what others have to say.. Thanks in advance to everyone and Happy New Year to everyone!

The simulation isn't based on anything from 2014. The simulation is based on modeling a cosmological theory and then comparing the output to observations. For the most part, that output looks very much like what we actually observe, which lends support for the theory.

Recent observations have raised questions about the early universe... just when it was, and just how stars and galaxies were forming so early. Those observations suggest that the cosmological models may require adjustment. I think it's doubtful that they will change radically, however, given the huge amount of evidence that supports their broad accuracy.

Hi Chris, I acknowledge and appreciate your knowledge and thoughts, only thing I have difference of opinion is about "possibility of radically different understanding of universe" that humanity will have in next 100 years if not just 25-50 years. Just imagine how understanding changed/evolved in last 100-200 years. Completely changed. I feel there will be significant new discoveries in coming decades which will change all calculations and understandings about everything we feel we "know/understand" so far (it's like people till 17th century thought they "knew" all and it all changed radically) - way redshift based distance/time calculations, beginning/ending/cycles of universe or even space and time, how old universe is, how it'd evolve/dissolve, what came first, what will happen at end, what is end, what's is really dark (matter and energy), how emptiness/nothingness/darkness is ONLY constant and all physical world and light is a manifestation (temporary).. so many things. Unlimited possibilities. Quest and understanding will keep changing radically. Just my personal thoughts.

[Chris Peterson]

It's great experiment and am sure lot of time, money, efforts, knowledge involved in creating this but I can't help resist the thought that maybe all this is moot with latest discoveries James Webb ? I mean, the whole thing was based on 2014, 9 years ago and tons of things have changed since then which at least have created lot of doubt into what we *thought* we knew and new question marks have come in (which is good in my opinion). I don't believe we still know how the universe began (mysterious lumps or uniform distribution.. we have no idea if galaxies formed first or dark holes, we have no idea how old is universe (how long it expanded and slowed down and expanded again), anything we don't know we seem to clump it with *dark* (matter and/or energy).. Scientists and researchers seem to be ignoring tons of things already well explained in ancient (5000-10000 years old) Indian Vedas and Puranas (including space, time, cycles of universe, multi-universes, evolution of species, calculations about cycles of universe, even string theory/vibration based basic of universe, .. etc).. It's mind boggling. I'm curious what others have to say.. Thanks in advance to everyone and Happy New Year to everyone!

The simulation isn't based on anything from 2014. The simulation is based on modeling a cosmological theory and then comparing the output to observations. For the most part, that output looks very much like what we actually observe, which lends support for the theory.

Recent observations have raised questions about the early universe... just when it was, and just how stars and galaxies were forming so early. Those observations suggest that the cosmological models may require adjustment. I think it's doubtful that they will change radically, however, given the huge amount of evidence that supports their broad accuracy.

Hi Chris, I acknowledge and appreciate your knowledge and thoughts, only thing I have difference of opinion is about "possibility of radically different understanding of universe" that humanity will have in next 100 years if not just 25-50 years. Just imagine how understanding changed/evolved in last 100-200 years. Completely changed. I feel there will be significant new discoveries in coming decades which will change all calculations and understandings about everything we feel we "know/understand" so far (it's like people till 17th century thought they "knew" all and it all changed radically) - way redshift based distance/time calculations, beginning/ending/cycles of universe or even space and time, how old universe is, how it'd evolve/dissolve, what came first, what will happen at end, what is end, what's is really dark (matter and energy), how emptiness/nothingness/darkness is ONLY constant and all physical world and light is a manifestation (temporary).. so many things. Unlimited possibilities. Quest and understanding will keep changing radically. Just my personal thoughts.

My view is that we know most of the laws that govern nature, and that changes in things that are incompletely understood (e.g. cosmology, the Standard Model) will be adjustments, not replacements. Nature appears simple and easy to understand. There aren't very many rules, and the techniques we've developed over the last century or so to learn them has proven extremely effective. It has been a long time since any fundamental natural theory has been replaced by something else.

Most science in the future (indeed, even now) will be about the study of the emergent properties of these simple, increasingly well understood laws.

[Pastorian]

Instead, I'll show you my favorite Illustris simulation!

Cosmic web Illustris TNG.png

Visualization of the intensity of shock waves in the cosmic gas (blue)
around collapsed dark matter structures (orange/white). Similar to a sonic boom,
the gas in these shock waves is accelerated with a jolt when impacting
cosmic filaments and galaxies.

Perhaps it is the time of year, but this very much resembles a tree whose limbs are wrapped in fairy lights. As above, so below.
https://sc01.alicdn.com/kf/HTB1y.bGdL5T ... nGFXa7.png
https://i.pinimg.com/originals/d6/1e/4f ... 257180.jpg

[johnnydeep]

Hard to fathom that all we see and think we understand comprises only 5% of the universe:

Click to view full size image

[Chris Peterson]

Hard to fathom that all we see and think we understand comprises only 5% of the universe:

Click to view full size image

But that doesn't mean that our understanding of nature is 95% incomplete!

[johnnydeep]

Hard to fathom that all we see and think we understand comprises only 5% of the universe:

Click to view full size image

But that doesn't mean that our understanding of nature is 95% incomplete!

Probably not. But I'd say until we know more about what dark matter is, we'd be hard pressed to put an accurate percentage on our total understanding of everything. "In theory", dark matter might be even more complex than normal matter, though I guess that dark energy is pretty simple.

[shaileshs]

Hard to fathom that all we see and think we understand comprises only 5% of the universe:

Click to view full size image

But that doesn't mean that our understanding of nature is 95% incomplete!

If it means we "understand" that we don't understand 95%, then yes, sure. We have no understanding (can't see, can't define, can't taste, can't analyze, can't hear, can't touch, can't test, can't taste..) nothing of neither dark matter nor dark energy. So, it's like yeah, we know that we don't know 95%. Better than not knowing what we don't know.. Again, just my individual opinion and perspective. Others can agree/disagree as they like.

[Chris Peterson]

Hard to fathom that all we see and think we understand comprises only 5% of the universe:

Click to view full size image

But that doesn't mean that our understanding of nature is 95% incomplete!

If it means we "understand" that we don't understand 95%, then yes, sure. We have no understanding (can't see, can't define, can't taste, can't analyze, can't hear, can't touch, can't test, can't taste..) nothing of neither dark matter nor dark energy. So, it's like yeah, we know that we don't know 95%. Better than not knowing what we don't know.. Again, just my individual opinion and perspective. Others can agree/disagree as they like.

We have many ideas about both, and they are testable and being tested. Most theories we're working with don't require any radical new physics or the replacement of any existing theories. I'd say we know 95% of what there is to know, not the other way around!

[Ann]

The simulation isn't based on anything from 2014. The simulation is based on modeling a cosmological theory and then comparing the output to observations. For the most part, that output looks very much like what we actually observe, which lends support for the theory.

Recent observations have raised questions about the early universe... just when it was, and just how stars and galaxies were forming so early. Those observations suggest that the cosmological models may require adjustment. I think it's doubtful that they will change radically, however, given the huge amount of evidence that supports their broad accuracy.

Hi Chris, I acknowledge and appreciate your knowledge and thoughts, only thing I have difference of opinion is about "possibility of radically different understanding of universe" that humanity will have in next 100 years if not just 25-50 years. Just imagine how understanding changed/evolved in last 100-200 years. Completely changed. I feel there will be significant new discoveries in coming decades which will change all calculations and understandings about everything we feel we "know/understand" so far (it's like people till 17th century thought they "knew" all and it all changed radically) - way redshift based distance/time calculations, beginning/ending/cycles of universe or even space and time, how old universe is, how it'd evolve/dissolve, what came first, what will happen at end, what is end, what's is really dark (matter and energy), how emptiness/nothingness/darkness is ONLY constant and all physical world and light is a manifestation (temporary).. so many things. Unlimited possibilities. Quest and understanding will keep changing radically. Just my personal thoughts.

My view is that we know most of the laws that govern nature, and that changes in things that are incompletely understood (e.g. cosmology, the Standard Model) will be adjustments, not replacements. Nature appears simple and easy to understand. There aren't very many rules, and the techniques we've developed over the last century or so to learn them has proven extremely effective. It has been a long time since any fundamental natural theory has been replaced by something else.

Most science in the future (indeed, even now) will be about the study of the emergent properties of these simple, increasingly well understood laws.

We haven't known about dark matter all that long. The phenomenon was originally deduced by Fritz Zwicky in 1933, after he had been studying the Coma Cluster of galaxies and concluded that there must be a lot more matter there than was provided by the visible matter only. Then (in the 1960s?) Vera Rubin confirmed the presence of unseen matter in galaxies.

As for dark energy, that is a much more recent discovery, from 1998, and I remember the shock waves it sent through the astronomical community at that time. I had been following the question of the expansion of the Universe for more than twenty years by then, because I had been in my twenties when I first came across the idea of a possible collapse of the Universe, a Big Crunch, and I had been horrified at the concept of the entire Universe crashing in on itself and obliterating itself in an all-encompassing cosmological train crash. I very much hoped that this fate wouldn't befall the Universe, so I read everything that was written on this topic in magazines like Sky & Telescope. That is why I remember so clearly how shocking it was to the entire astronomical community to realize that the Universe was not just expanding, but accelerating.

My point? Maybe we aren't out of shocking discoveries about the Universe just yet. But that is only my amateur opinion.

Ann

[shaileshs]

Hi Chris, I acknowledge and appreciate your knowledge and thoughts, only thing I have difference of opinion is about "possibility of radically different understanding of universe" that humanity will have in next 100 years if not just 25-50 years. Just imagine how understanding changed/evolved in last 100-200 years. Completely changed. I feel there will be significant new discoveries in coming decades which will change all calculations and understandings about everything we feel we "know/understand" so far (it's like people till 17th century thought they "knew" all and it all changed radically) - way redshift based distance/time calculations, beginning/ending/cycles of universe or even space and time, how old universe is, how it'd evolve/dissolve, what came first, what will happen at end, what is end, what's is really dark (matter and energy), how emptiness/nothingness/darkness is ONLY constant and all physical world and light is a manifestation (temporary).. so many things. Unlimited possibilities. Quest and understanding will keep changing radically. Just my personal thoughts.

My view is that we know most of the laws that govern nature, and that changes in things that are incompletely understood (e.g. cosmology, the Standard Model) will be adjustments, not replacements. Nature appears simple and easy to understand. There aren't very many rules, and the techniques we've developed over the last century or so to learn them has proven extremely effective. It has been a long time since any fundamental natural theory has been replaced by something else.

Most science in the future (indeed, even now) will be about the study of the emergent properties of these simple, increasingly well understood laws.

..
..

My point? Maybe we aren't out of shocking discoveries about the Universe just yet. But that is only my amateur opinion.

Ann

True that Ann! I completely agree.

I think I've seen most scientists who have best/most knowledge seem to agree with my assessment (that we really don't know much at all, forget 95% "dark" stuff, even not much about 5% light/physical matter).

People before Einstein or even as recent as before 1998 thought they knew a lot and then everything changed (space-time, relativity, expansion...).

I'm sure 50-100 years down the road, people living that time will have different understanding of universe (including some basic laws of physics that'd need to be redefined, some basic assumptions and calculations about redshift and distances and even gravity will be completely changed), even the age of universe will get recalculated to 100s of trillions (not just 13.8 billions), the size will be infinite, some new discoveries based on reverberations/string theory/quantum physics etc will prove things radically different than what we know today and they'd wonder how people living in 20## believed in something total false..

It's better to be cautious and accept and assume we don't know much than thinking reverse (as even @sadhguru says, we have to seek (if we feel we know most then that's mostly end of seeking).

Again, just my personal (lay person's) opinion and last word on this from my side.

Happy New Year everyone!