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insosinoadura: on 8/11/10 at 16:36pm UTC, wrote Any conversion coming from twelfth grade to help university or college...

Lawrence B. Crowell: on 2/22/09 at 0:50am UTC, wrote I also wrote a computer program recently which illustrates something about...

Saibal Mitra: on 2/21/09 at 23:57pm UTC, wrote Even in pure mathematics, (computer) experiments often lead to a new... on 2/18/09 at 3:29am UTC, wrote (If my blog seemed angry in any way i didn't intend for it to be that way....

Lawrence B. Crowell: on 2/17/09 at 23:06pm UTC, wrote What do you think would happen? I'd recommend investing heavily in the... on 2/17/09 at 21:55pm UTC, wrote Say if i told a every single person earth that everything they've ever... on 2/17/09 at 21:43pm UTC, wrote Witchy-well thats just me. i don't have a habit of spelling correctly in...


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Georgina Woodward: "Robert, thank you for explaining very clearly. "Of course, as is..." in Schrödinger’s Zombie:...

jaime allen: "There are many topics like these, and all of them are helping me to become..." in Equivalence Principle...

Robert McEachern: "Georgina, It may help you come-to-terms with the fact that a "huge..." in Schrödinger’s Zombie:...

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First Things First: The Physics of Causality
Why do we remember the past and not the future? Untangling the connections between cause and effect, choice, and entropy.

Can Time Be Saved From Physics?
Philosophers, physicists and neuroscientists discuss how our sense of time’s flow might arise through our interactions with external stimuli—despite suggestions from Einstein's relativity that our perception of the passage of time is an illusion.

A devilish new framework of thermodynamics that focuses on how we observe information could help illuminate our understanding of probability and rewrite quantum theory.

Gravity's Residue
An unusual approach to unifying the laws of physics could solve Hawking's black-hole information paradox—and its predicted gravitational "memory effect" could be picked up by LIGO.

Could Mind Forge the Universe?
Objective reality, and the laws of physics themselves, emerge from our observations, according to a new framework that turns what we think of as fundamental on its head.

September 16, 2019

CATEGORY: Blog [back]
TOPIC: The Simulated Universe [refresh]
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Blogger Grace Stemp-Morlock wrote on Feb. 13, 2009 @ 18:55 GMT
Well, it's the first real day of the AAAS meeting in Chicago and I’ve found myself in a little session reviewing how supercomputers are improving astrophysics simulations. The simulations are just gorgeous and really scientifically important too.

Cal Jordan / Unversity of Chicago Flash Team
In a field like astronomy, doing experiments can be really hard. But, as computers continue to grow bigger and bigger the quality of the simulations increases. The development of supercomputers and their application to astrophysics was the focus of a talk by Robert Rosner, the Director of Argonne National Laboratory in Chicago, on Friday morning.

“Astrophysics is one of the remote sensing sciences,” said Rosner. “We’re not allowed by nature to blow up stars. We’d like to maybe, but we can’t. Some of us have been trying to do this since we were kids, but nature says we can’t.”

Instead, what astronomers can do is develop theory and run a simulation. However, the computers running those simulations had been too limited up to this point to provide the much needed information. It’s tough to see anything as small as a galaxy, forget about solar systems or individual stars.

But over the past few years, the most powerful computers in the world have given us some good results and we had a look at some of the highlights in this session. One of the first projects was conducted by the University of Chicago’s Center for Astronomical Thermonuclear Flashes (one of the coolest sounding organizations in astrophysics) to understand how a type 1A supernova explodes.

The implications were huge for understanding type 1A supernovae since they are used in countless measurements as an astronomical yardstick. The group got time on the Lawrence Livermore National Laboratory supercomputer, the fourth largest in the world.

The simulation shown at the presentation was nothing short of spectacular, and if you want to see similar simulations you must check out the Astronomical Thermonuclear Flashes webpage to see the movies.

What they discovered (besides how awesome a simulation can look) is that their understanding of how a supernova explodes was wrong.

As Rosner explained, the theory had been that when you try to get something to explode, say a piece of wood, you can’t just light it. If you light a log on fire it might smoke a bit, but if you chop it up into smaller kindling sticks then you will get a good fire. Even better would be to turn it into sawdust, throw it in the air, and then light it for a really big bang.

However, surprising as it might seem that was not the way it worked. Instead a shock wave travels around the star from the flash point, and when it reaches the antinode on the other side of the star, the waves crash into each other shocking the core and causing a huge detonation.

John Dubinski
Rosner’s talk also featured a simulation of a galaxy collision between the Milky Way and Andromeda galaxies by John Dubinski, an astrophysicist at the Canadian Institute for Theoretical Astrophysics in Toronto – obviously something we can’t do in reality. The collision was in the news a lot a couple of weeks ago because the this cosmic smash-up might happen sooner than we thought—within the next seven billion years.

Dubinski has created an entire small enterprise and website to show off his simulations of galaxy collisions, which in addition to being scientifically important are also artistically beautiful. You can see some of them on his galaxy dynamics page.

The promise of more simulations on the way has got me wondering: Should the Hubble Space Telescope be worried about its dominance of the astronomy visuals marketplace?

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report post as inappropriate wrote on Feb. 14, 2009 @ 05:55 GMT
I fear that it might. I believe that if people found out how the universe really works. Either a civil war would break out between the scientific community, and the religious communty, or religion would die out and crime would escalate to the point where the usa would fall apart. So if I were the scientist who figured that out correctly (me), i'd keep it away from the genneral public. The truth can be life changing!

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report post as inappropriate wrote on Feb. 14, 2009 @ 06:08 GMT
I sorta didn't the question at the end correctly before i published. Anyway, think about this fact: in order for something to be infinite it must first be made of nothing. It actually go's pretty far. If you want to see a paper on this. You'll have to wait until next year. Feel free to email.

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Lawrence B. Crowell wrote on Feb. 14, 2009 @ 12:40 GMT
The computer is not going to replace the telescope. The telescope gives information about the universe as it is. The computer tells us how our best ideas produce results in complex configurations. Graphics transduce these results in ways that are visually apparent. Direct observations of the distant universe can reveal systems in various states of development. It would be as if some ET came to Earth and went through a hospital on a brief tour and saw babies in the neonatal ward, children at pediatrics, and up to seniors in a geriatric ward. The ET then deduces something about our life cycle. So too we do much the same for the life cycle of stars and other objects. The computer then allows us to put all of this together to model the astrophysics of stellar evolution or galaxy clusters in the exapnding universe.

I should say I hope this is the case. There are reasons to suspect that the whole human race may plunge completely into our own virtual world(s), as simulated games & cycber worlds become more sophisticated and cell phones interface increasingly with our senses, maybe even directly into the brain. Maybe in 50 years the primary nodes on the internet will no longer be of silicon, but of neurons.

Lawrence B. Crowell

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Myke wrote on Feb. 14, 2009 @ 17:41 GMT
Hi Grace, well the universe as it was and as it may be is a great study. However, when it comes to supernova trigger mechanisms, the truth is apparently even stranger; please read my essay on time on this site, page 7 and figure 6 in particular, thanks...

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Witchy wrote on Feb. 15, 2009 @ 09:41 GMT
Sorry Atomiton1 but I completely disagree with you. I don't think that any scientific revelations, no matter how earth-shattering, would lead to the circumstances you describe:

1) People are well aware how much of all science, let alone astrophysics, is conjecture (my own brother has a first in the subject). And humans are very doubting creatures nowadays - even if a Messiah appeared to us we'd probably think it a media trick.

2) People are supremely indifferent to things unless they affect them here and now. Saying the galaxy may collide in 7 billion years won't cause any anxiety at all when you consider how well proven it is that we are currently already systematically destroying this planet. And yet do any of us give up our cars? Very few - I know I don't.

(Also, sorry and I know this is very old-fashioned of me, but if you're planning on releasing a paper for people to take seriously, I'd suggest a decent spell and grammar check.)

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Lawrence B. Crowell wrote on Feb. 15, 2009 @ 12:25 GMT
I would largely agree. There are very few cases of scientists who have faced violence because their work contradicted religious beliefs. Science does illustrate things about the univerese which rattle people's comfort zones. Yet generally religious people simply deny the science and stick within their communities.

The main social impact here is this is an extension of the whole virtual reality or cyber space advancement. The growth of virtual reality and media generated alternative realities is blurring the lines between objective reality and fantasy. Internet multi-user sites, such as Second Life and World of Warcraft, are becoming for many people their primary mode of existence. The cyber-generated landscapes these systems produce will improve with time and people may only go offline when they absolutely must. Other digital changes are occurring, such as constant realtime GPS information of your location. Continual RFID data streaming to local processors. Already those advert screens in large stores collect data on people who pass by, where I suspect before long that will include RFID and the interface of that will cell/blackberry systems. Before long where you are, who you are with, where you are on the internet will be constantly recorded and processed for various purposes. Those purposes will range from marketing to national security. I suspect these will in turn link ever more closely with our senses, and may be eventually connection into our brains. If this comes at some time in future your thoughts may be directed and recorded.

Of course simulated astrophysics plays a tiny role in this. In fact it is one case of where computers continue to be employed in something which is enlightening, where computer applications have been increasingly directed at info-tainment, marketing, hyper-commercialism and the rest. Though in reference to what I write above we might find that for many people a digital rendering of astrophysics might be indistinguishable from telescopic of sensory images of the universe.

Lawrence B. Crowell

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Witchy wrote on Feb. 15, 2009 @ 15:47 GMT
The possible social impact of computer technology is indeed quite fascinating and disturbing. The virtual world is sucking people in more and more (Facebook, anyone?) and, as well as the dangers of social control that Mr Crowell describes, are we not also desensitising ourselves still more to suffering and violence? Look at the first Gulf War and how the media was able to portray the missiles being launched as "clinical" and exact, using clips that resembled computer games. (The reality of course was continued collateral damage.) Detachment from reality will surely only increase the existing lack of understanding of consequences that already pervades Western culture.

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Lawrence B. Crowell wrote on Feb. 15, 2009 @ 18:00 GMT
We live in an age where all our ideological, socio-economic, religious, and social conventions are disintegrating. In particular on the political and economic front everything is falling apart. Marxism has been reduced to historical dust, though Hugo Chavez seems to be trying to breath new life into it in Venezuela, and the free-market neoconservative ideology which has run this nation and the world is entering a state of utter collapse.

What might be replacing it is the cyber-world, which over the next 50-100 interlinks brains. If this becomes the case everything we are familiar with, nation-states, academia, organized religion, corporations ... will become socio-economic sugarcubes in water.

Lawrence B. Crowell

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report post as inappropriate wrote on Feb. 17, 2009 @ 21:43 GMT
Witchy-well thats just me. i don't have a habit of spelling correctly in blogs. heck mabe i failed english (wich i didn't). nomatter, an idea can be can be used to express thoughts true or not about the universe. I have a habit of being able to answer the toughest of questions by breaking them down and putting them back together, and being able to tell fiction from non. Even though i might exadurate from time to time. Such as worst case scenarios, but i still end up right in the end.

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report post as inappropriate wrote on Feb. 17, 2009 @ 21:55 GMT
Say if i told a every single person earth that everything they've ever believed in was rong, if i told them if god didn't exist, if i told them their lifes were all lies, and if I said that if they didn't accept that then they would die. What do you think would happen?

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Lawrence B. Crowell wrote on Feb. 17, 2009 @ 23:06 GMT
What do you think would happen?

I'd recommend investing heavily in the alcohol industry. We are already there. All our cherished beliefs are falsehoods, there are no gods, and at least in my nation we have been living under a phoney economy where we all pretended to be busy --- we already know our lives are lies. Drink up!

This has gone a bit afar from the subject of the blog page. I imagine it is impossible to know with certainty the dynamics of galaxy collisions, for we can't watch the whole process. The supernova simulation might be observationally benchmarked, for the collision of the shock wave around the body should have some observational consequences.

Lawrence B. Crowell

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report post as inappropriate wrote on Feb. 18, 2009 @ 03:29 GMT
(If my blog seemed angry in any way i didn't intend for it to be that way. As i said i do exadurate a bit, and i guess i did on this blog. By the way i dought a 15 year old could get away with drinking.) The universe really isn't that hard to figure out. If you know how to look at it. I don't know who made the model for the atom, but i do know they were wrong (that has alot to do with why a supernova creates a black hole). Did you know the atom acctually works like our solar system. email if interested.

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Saibal Mitra wrote on Feb. 21, 2009 @ 23:57 GMT
Even in pure mathematics, (computer) experiments often lead to a new result, the proof often comes later, see here

An ordinary PC is sometimes all you need, see e.g. a result I found recently using computer experiments:

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Lawrence B. Crowell wrote on Feb. 22, 2009 @ 00:50 GMT
I also wrote a computer program recently which illustrates something about physics. It integrated the "zig-zag" motion of an electron (or any lepton or quark) according to the 2-component Weyl equations. The mass or Higgs which does the scattering is a dynamical field. I attach a motion file which illustrates this. I had some trouble getting the frames stable, but it gives the basic idea. The wave function swish-swashes back and forth.

Computers are clearly valuable tools, which as time goes on is for most applications sort of info-tainment toys.

Lawrence B. Crowell

attachments: zitterzag.gif

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