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Posts by Cluster Physik

1) Message boards : Application Code Discussion : Source Code of ATi app (Message 50545)
Posted 5 Aug 2011 by Cluster Physik
Post:
It's probably a bit late to answer here. But I want to explain a bit the course of events from my point of view.

To say the truth, the whole thing started indeed in a quite grey area. The source I began with (not only me, there were at least one other guy before) had no license, so I was bound only by copyright issues. Under those terms, the copyright holder could have demanded, that I stop what I was doing. But that simply never happened.

Quite to the contrary, an exchange via PMs and email developed, where I shared code fragments as well as ideas for optimizations. For the Radeon versions, I basically got requests from Travis/Anthony to look into some issues and provide fixes. There was indeed some cooperation going on, which ended up in a publication the MW team and me authored together (and I've written quite a bit of the text in there). Also one shouldn't forget that the MW project itself distributed my applications as stock apps for Radeon GPUs. Claiming afterwards, I was violating their copyrights by compiling those versions sounds not only a bit ridiculous. At this point I had at least a silent consent/tacit approval for my work (which is legally relevant, just to mention it).

But I understand, that Matt wasn't happy about writing a CAL version of the program on his own. And admittedly, I said I will provide the project with the complete source code after a cleanup (it looked really messy as all the changes, fixes, and additions were basically done on the fly). In fact I had already started with that as you can see at the nicely commented CAL kernel I posted at the beginning of this thread. Unfortunately I had not much time back then (I communicated that to Travis and Anthony), as my PhD defense was just two weeks after the just mentioned post. So I was really busy for my actual work. After all, this just started as a small hobby project and was never meant to take so much of my time. And when I had to decide between doing my job (after my defense there were some urgent projects to finish before my leave) as well as finding a new position afterwards on one hand and doing some voluntarily and time consuming stuff for MW@home, I opted for my job.
The last communication I received from the MW project was on the very day before I started with my new position (in another city, so I had to find a new flat, move and all that stuff on top of getting to grip at work). So while I'm sorry I didn't contribute anymore, there was nothing I could realistically could do back then.
And afterwards I simply lost track. It isn't that way that I was still around and simply didn't want to do something. I also lost the connection to my team (P3D, I'm still a member, but I was not around in their forum and didn't contribute there neither).

And frankly speaking, it isn't that way the source code hadn't to be rewritten either way. As said, the host code was quite convoluted and the GPU code written on a really low level (I was thinking about using calpp, the same what is apparently used now, too). So what would have been the alternative to Matt rewriting it as part of his work as a student on the project? Me as an alleged copyright infringer rewriting it just for fun/free of charge for the project? Yeah. But anyway, I would have done it under different personal circumstances/at another time.

By the way, I just had a glimpse over the current source code. For me it looks like Matt was able to "borrow" quite a few ideas from the stuff I shared (some codeparts are simply back-translated from CAL-IL to CALPP, it is virtually identical), same as Travis did before with the CPU versions (and even the nvidia versions). Is that infringing on any license? Of course not, the code came without a license. Is that infringing on any of my copyrights. No, I posted it in the (not explicitly stated) intent that others/the project uses it/learns something from it/get the underlying ideas to improve on the project. Of course they had my implicitly given consent.
2) Message boards : News : OSX applications updated again to v0.31 (Message 40580)
Posted 22 Jun 2010 by Cluster Physik
Post:
Any news regarding an ATI GPU client for Snow Leopard?

I guess it may arrive with the OpenCL variant (I think the project is actively working on that) as the current ATI application would be very hard to port (there is simply no SDK for the programming environment I used for Macs).
3) Message boards : Number crunching : Can MW ATI app run on CPU exclusively? (Message 40579)
Posted 22 Jun 2010 by Cluster Physik
Post:
Please, look at this picture. It shows 4 MW ATI app running in task manager while only 1 MW task running on GPU as BOINC thinks. It shows other MW tasks running on CPU only! This causes out of memory state for ATI AP app running on secondary GPU on that host.
Any ideas how it could be and what could be wrong in MW setup there ?

http://img694.imageshack.us/img694/4797/17454729.png

I would guess that guy is using some modified app_info.xml which schedules the MW GPU application as CPU application. But if it is started without a --device argument, it will use the integrated backup scheduling mechanism for pre 6.10 clients (the stuff with the semaphores) and run on the GPU either way.

So my advice is to check the used app_info.xml.
4) Message boards : News : updating the stock osx/linux/windows applications (Message 40561)
Posted 21 Jun 2010 by Cluster Physik
Post:
Some update from my side:

It runs now with the newer SDK version, but unfortunately I had to recognize, that a lot of nasty bugs or "features" survived. Heck, I complained about wrong indexing when using double precision constant buffers 18 months ago, I even sent a test case to ATI's stream developer team back then! That makes it more or less impossible to write the ATI GPU code completely in a high level language, one needs to correct the code on the underlying CAL/IL level. I can only hope that the OpenCL compiler was more in the focus of ATI lately. It really looks like nobody actually tested the double precision stuff within their compilers as there are plenty of problems with it but generally it works with single precision.

@Travis:
I hope you don't want to rewrite the integration kernels from scratch (I would almost suggest looking at OpenCL if that need arises, or alternatively CAL++ for ATIs, if you want more speed). But as I said before, changes to the likelihood stuff are no problem at all.

Edit:
I've just seen you added the possibility to use another "background profile" in the MW3 0.05 code (besides quite some other changes). If used, one would need to rewrite the GPU kernels. I will see, if I can look into it tomorrow.
5) Message boards : News : updating the stock osx/linux/windows applications (Message 40556)
Posted 20 Jun 2010 by Cluster Physik
Post:
Does CP's op ap need updating as well?

Yeah, there's a bunch of updates that we need to get done so we can swap over to the assimilator/validator that doesn't generate files for each WU and for each result.

Hopefully he gets settled at his new post doc and can work with us or send us the code so we can update it.

I will start my post doc position in two weeks.

Has anything changed since this post here and your summary there?
That version from april was already compatible with parameters given in the command line and wrote the integrals and likelihood also separately to the stderr.txt. Changes to the likelihood calculation should be really easy, as it is done on the CPU, not the GPU.

I will try to update the ATI app to use the newer Stream SDK (I was still using the outdated SDK 1.3 so far) this evening. Some changes will be needed, as SDK 1.3 didn't support multiple GPUs or the CPU release during the GPU kernels, I implemented that as some kind of small hack to the old SDK (it is open source). But the newer SDKs have official support for those features (that's why I want to use it), but it works of course a bit different than my version. I will see if all fits nicely or if some more changes are needed.

I've done also some changes to the boinc_api to fix some problems there, I don't know if it is still necessary or if Berkeley has fixed those issues (like the suspend/resume problem when using critical sections) since the last time I looked at it. But I will detail it when I send the code.

And be warned already, I never had time to clean it up, so it may look a bit convoluted. After all, it still bases on the 0.07 code, I only adapted it to stay compatible with the newer versions without investing any effort to increase the readability.
6) Message boards : MilkyWay@home Science : Is it posible that the universe are colapsing at this very moment? (Message 40519)
Posted 18 Jun 2010 by Cluster Physik
Post:
It can be argued that the most interesting discovery would be that we cannot find the higgs proving practically that it isn't there. That would mean that we really haven't understood something, that's a very good scene for science. Revelations sometimes come from the fact you hit a wall and you realize that you truly haven't understood anything.

That's what the bearded dude states. I agree, that's how science works. In essence, we don't find it, we've been wrong all along? Haven't understood Quantum Mechanics?

It means, that then the Higgs mechanism isn't responsible for the masses, or at least not in it's current version. That's what he finds interesting, to look for other explanations that may reveal some new, deeper principles.

That's what I said already, in that case one has to look at another or a refined mechanism for that. But it wouldn't invalidate quantum mechanics. Not by a long shot.
7) Message boards : MilkyWay@home Science : Is it posible that the universe are colapsing at this very moment? (Message 40517)
Posted 18 Jun 2010 by Cluster Physik
Post:
Well, pardon me. Sounds more like you can't defend an incomplete theory. No Higgs, no theory.

That's kind of how it works.

No, it's not.
The Higgs mechanism is only the best bet (right now) for that missing part of the standard model. There are in fact a few other ones which one has to look at, if the Higgs would not be found.

And as food for thought, that we have now quantum mechanics, doesn't make the classical mechanics useless. The latter is simply a limiting case of the former.

Edit: Even better. Here's the link to a youtube video where the scientists say what i just told you. No Higgs, no theory.

http://www.youtube.com/watch?v=_XbKZwXK-3c&feature=related

I suggest you go trolling there for information straight from a LHC scientists mouth.

I suggest you try to understand what the people are saying there.
8) Message boards : MilkyWay@home Science : Is it posible that the universe are colapsing at this very moment? (Message 40512)
Posted 18 Jun 2010 by Cluster Physik
Post:
But quantum theory is NOT a complete theory until the higgs mechanism is found. No proof, no cigar, unworkable theory.

One simply cannot PROVE

That sounds like you are trolling. Maybe I should stop feeding you :]

Edit:
By the way, it is not possible to prove that any theory is "true" and in a rigorous view, every theory is only an abstraction of the world. All what can be done is to check if a theory consistently describes the observations and experiments and if it has predictive value for new experiments. And frankly, quantum mechanics and the standard model as a whole does a quite marvellous job so far. But it is also true that the theory currently reaches to the edges what can be checked experimentally. So there is always the possibility that the theory needs some refinement, when new experiments come up. This is called scientific progress.

To sum it up, one can work quite well with current theories.
9) Message boards : MilkyWay@home Science : Is it posible that the universe are colapsing at this very moment? (Message 40510)
Posted 18 Jun 2010 by Cluster Physik
Post:
And when you have a higgs boson and a graviton that justify and qualify the other 16 particles, one can start spouting QM as a usable, testable theory. Not a mathematical theory that produces questionable experimental evidence based on hypothetical particles.

The graviton has nothing to do with the standard model. It was only proposed to exist in analogy to the other exchange particles, but it is not part of the theory.
We have currently quantum mechanical formulations of the electromagnetic, the weak and the strong interactions, the gravitation isn't part of this. There is simply no quantum mechanical formulation of gravitation, all we have is the good old classical gravitation (which is quite good for most stuff actually) and Einstein's General Relativity (which isn't a quantum theory either).

So more or less all what was proposed for the graviton so far is something like: "if something similar to the other 3 theories exists, we shall name the gauge boson (exchange particle) of gravitation the graviton". It is not clear if a gauge invariant quantum theory of gravitation even exists. All tries for a formulation failed so far (one of it was even termed "last hope theory").

The quest for a quantum gravitation theory is still open (and highly speculative as experimental checks are extremely difficult). In the moment it looks like as it will be a bit different than what we have for the other 3 interactions (which are all gauge theories). Loop quantum gravitation is apparently something else (I don't know what they are talking about ;) where maybe no graviton is needed at all.

But back to your quote. Quantum mechanics is so well tested and proven that your quote above simply makes no sense at all. A lot of stuff around you wouldn't work without it!
10) Message boards : MilkyWay@home Science : Is it posible that the universe are colapsing at this very moment? (Message 40507)
Posted 18 Jun 2010 by Cluster Physik
Post:
That's why I said earlier that such advanced theories are currently not much more than playing around with some advanced mathematics without any factual base.


But that also encompasses the big bung theory. Alan Guth, inventor of the Inflation theory (bolted on to the big bung) freely admits that his calculations, and theory, is wrong. Yet big bungers hold on to the thought religiously. Why?

Again, you are mixing something up. There is clear evidence for the Big Bang and there are some observed properties of our universe, which may be explained by one or more inflationary phases. Those theories are being worked on and their predictions are currently checked against measurements and observations (like the cosmic background radiation data).
And yes, it is right that Alan Guth in his original work (where he came up with the inflation idea) used a too simple model. But this is not the end of it all. There are competing models, extensions to it and generally a lot of people trying to improve the theory. This is simply work in progress.

And the Casimir effect, how is that justified with 16 elementery particles, +2 hypotheticals. Don't they need their opposite spin particles to make sense? Those other 16 particles that were MADE UP i.e. NO EVIDENCE FOR except the fact that mathemeticians needed them for QM to make sense?

I know the 16 already observed elementary particles of the standard model and the sole missing one is the Higgs. What is the second hypothetical?

And by the way, the 16 known particles have of course their antiparticles (the photon and the Z0 are their own antiparticles), which were observed too. But the spin doesn't change of course. What do you mean with "opposite spin"? Spin is a quantity which can only have positive values (greather than or equal zero). So I have no idea what you are talking about.

Or are you mixing the standard model with something you heard about some proposed supersymmetry theories? That would be of the quite speculative category (and unlikely that it is correct as there are a whole bunch of competing theories). But it wouldn't change anything on the Casimir effect either way.
11) Message boards : MilkyWay@home Science : Is it posible that the universe are colapsing at this very moment? (Message 40490)
Posted 17 Jun 2010 by Cluster Physik
Post:
So, is this electromagnetism explained in another way?

No, it's the Casimir effect ;)
It was predicted in 1948 and measured 8 years later.

The vacuum fluctuations happen not only with an electromagnetic field but for everything. The textbook experiment is only designed to measure the electromagnetic part as it is the easiest (lowest energies and the longest wavelengths). But is has proven and measured implications also for the strong(*) interaction between quarks for instance.

(*):
There are 4 fundamental forces in the universe which possibly unify at very high energy scales. The electromagnetic, the weak, the strong interaction, and finally gravitation. The unification of the electromagnetic and the weak interaction can be considered theroetically understood and experimentally more or less proven up to the still pending detection of the Higgs particle. Theories for three forces (Grand Unified Theories, GUTs) are being developed, but hard experimental checks are probably far far away. The "holy grail" would be to embed some sort of quantum gravitation for a unification of all 4 forces.
That may show how far we are currently away from such stuff, as it is not really possible to check even the GUTs (there are a lot of competing ones) and we are still struggling to find the last pieces of the puzzle for the electroweak unification. That's why I said earlier that such advanced theories are currently not much more than playing around with some advanced mathematics without any factual base.
12) Message boards : MilkyWay@home Science : Is it posible that the universe are colapsing at this very moment? (Message 40489)
Posted 17 Jun 2010 by Cluster Physik
Post:
No. The universe as a whole came into existence about 13.7 billion years ago. We know that, because no light older than that had the chance to reach us so far.

Didn't you say though that there's part of the universe beyond our viewable range? Please be consistent.

There is no inconsistency.

Looks like you mix up now quite some stuff. Hawking had nothing to do with the Big Bang idea for instance and he didn't invented the singularities either.

Penrose penned (pardon the pun) the singularity, Hawking 'borrowed' it as the source of the big bang.

Uhmm, no. The origin of the idea with the Big Bang starting from a very dense state is Georges Lemaître who formulated that idea already in 1927.
Penrose and Hawking have only proven (much later) that there are no solutions of Einsteins field equations completely without singularities.
By the way, singularities are in fact only mathematical constructs which should give a strong hint to every physicist that some part of the theory is still missing. So in fact they have proven that Einstein's equations are no complete theory (which is a well known fact).

There is some concept named energy conservation which is generally fullfilled except on very short time scales. That is where the vacuum fluctuations come into the game. And by the way, the total energy of the universe may be zero ;)

Vacuum fluctuations? Theory? No facts? Not provable but invented to fill a knowledge gap? We aren't talking gravitons are we? Of course not. We're quoting Hawking again. The man that gave us the unworkable multiple universe theory. Well, he thought it worked anyway.

Again, only because Hawking has written something about it in his "Brief history of time" doesn't make him the original source of the idea. Vacuum fluctuation were known long before (they are in a sense a consequence of the Heisenberg uncertainty principle formulated also already in 1927). And the vacuum fluctuations have measurable and proven consequences (you may look up the Lamb shift), even as some details are not fully understood yet (there are for instance some problems when one tries to calculate the Casimir effect from vacuum fluctuations, there are also competing interpretations of the Casimir effect which may be a better fit).

http://www.braungardt.com/Physics/Vacuum%20Fluctuation.htm
It is possible to settle the issue by a simple calculation. Astronomers can measure the masses of galaxies, their average separation, and their speeds of recession. Putting these numbers into a formula yields a quantity which some physicists have interpreted as the total energy of the universe. The answer does indeed come out to be zero within the observational accuracy.

That's Hawking's zero energy. But that doesn't account for our dark matter or dark energy, does it? So is Hawking wrong, or wrong?

No, that's not "Hawking's" zero energy. The gravitational potential of some masses is known for some hundred years now, the same is true for the kinetic energy. Only for Einstein's E=mc² we had to wait a little bit longer. But summing all up is hardly a breakthrough. The total energy of an isolated system (as our universe) is known to be conserved and constant for ages now, one should learn this latest at College if not already in the high school. It is a common quantity to characterize a physical system.
By the way, it doesn't matter which kind of energy/matter our universe consists of, that calculation should work always.
13) Message boards : MilkyWay@home Science : Is it posible that the universe are colapsing at this very moment? (Message 40483)
Posted 17 Jun 2010 by Cluster Physik
Post:
it doesn't explain this..

http://en.wikipedia.org/wiki/Galaxy_formation_and_evolution
In 2007 the Keck telescope, a team from California Institute of Technology found six star forming galaxies about 13.2 billion light years (light travel distance) away and therefore created when the universe was only 500 million years old.
Damn, i'm using evil Wiki.

Of the oldest observable light, our universe is 13.7 billion years old. But what about the part of the universe we can't see, beyond the horizon? I assume it's still part of our 'universe' by your own definition.
So how, with any accuracy, can we predict when galaxies first formed? There could be 20 billion light years worth of creation beyond our horizon. Well, that could mean we don't really know squat about what formed and when. Correct?

No. The universe as a whole came into existence about 13.7 billion years ago. We know that, because no light older than that had the chance to reach us so far. That is simply defined by the size of the visible universe and the speed of expansion one can measure. Because this process (and the whole universe) is so isotropic, there is simply no reasonable explanation how some parts of the universe could have existed somehow earlier than other parts. One would be able to detect that through a far greater anisotropy in our universe as observed.
14) Message boards : MilkyWay@home Science : Is it posible that the universe are colapsing at this very moment? (Message 40482)
Posted 17 Jun 2010 by Cluster Physik
Post:
I find it difficult to fathom basing the current fate of the universe whilst only knowing a % of the whole picture.

That is called science. If we would know the complete picture, one wouldn't need to think about it any further ;)

The Hartle and Hawking No-Boundary Proposal

In the current state, all that stuff is mostly just some theorization without supportive evidence from observations. A nice gimmick if you want.

The same idiot that gave us singularities and big bang's. First he comes up with multiple universes, then we get 1 from a big bang.

Looks like you mix up now quite some stuff. Hawking had nothing to do with the Big Bang idea for instance and he didn't invented the singularities either.

Where did the initial big bang 'singularity' suddenly appear from? Not there 1 microsecond, expanding exponentially the next.

It does not matter, as it has no influence on our universe. Even when it may be possible to solve this scientifically (one idea would be the vacuum fluctuation I mentioned already (at the end)), I don't see the scientific value. We may want to ask this question for our own curiosity because one may see it as the the ultimate question of life, the universe, and everything, but strictly speaking the answer has no real value, just like "42" ;)

I atleast give M-Theory a rap for having a go at explaining it, whilst current science palms it off to philosophers to debate over. Puts it in the too hard basket as it interferes with their current theory.

M-theory won't explain how the universe came to existence. Furthermore, it first has to grow into a consistent theory (which it isn't currently).

Matter can't be created or destroyed? Law of some sort? ;) 'Big bang' energy came from....

There is some concept named energy conservation which is generally fullfilled except on very short time scales. That is where the vacuum fluctuations come into the game. And by the way, the total energy of the universe may be zero ;)
15) Message boards : MilkyWay@home Science : Is it posible that the universe are colapsing at this very moment? (Message 40479)
Posted 17 Jun 2010 by Cluster Physik
Post:
The universe by definition, as all that we know. Are you claiming we now know everything that there is to know?

No, the universe is all that is. It doesn't matter if we know it, it only has to be ;)

There is a reason I wrote that there is not even an outside.

So, answer the question. When i peer through the event horizon, what do i see? What do i travel into? The ocean with the fish in it?

You are not able to go through the horizon of your visible universe. The universe will always look spherical with you in the center and the horizon moves away from you with the speed of light in all directions, always. It doesn't matter how fast you travel or where you are. It also means that for a hypothetical guy at the left edge of your visible universe and another one at the right edge the universe will look different and they possibly don't see each other.
If you ask what is outside of your visible universe, the answer is all the remaining parts of the universe. We can only see an infinitesimal part of the total universe. As I said, the event horizon of the visible universe isn't material in any way. It is simply defined as moving away with the speed of light under all circumstances since the Big Bang.

And how do you come to the conclusion that gravitation is far to weak to influence the expansion? There is experimental evidence for about 27% of the mass needed to asymptotically stop the expansion. The open question is if we find the missing 73% or if those are comprised of the still hypothetical dark energy.

You answered your own question.

I wouldn't consider a factor of 4 or less significant or a major hurdle. Only 40 years ago we've known only 2% of the necessary mass. We found already a factor of 10 or so in the meantime ;)
16) Message boards : MilkyWay@home Science : Is it posible that the universe are colapsing at this very moment? (Message 40477)
Posted 17 Jun 2010 by Cluster Physik
Post:
Explain to me what the universe is expanding into...that is, the event horizon of the universe. What's on the other side of the wall?

To add something to my above post, there is no "wall" in a material sense. The "event horizon" of the universe defines only the visible part of the universe, or in another sense the part of the universe which can possibly affect us right now. Depending on the way the universe expands (or shrinks), it is allowed for instance that matter virtually "disappears" at the edges of the visible universe in case of an accelerated expansion. It simply means that some part of the universe which was formely within our visible universe (moves slower than the speed of light away from us) is now faster than light (the horizon always moves away with the speed of light from you and that since the Big Bang).
One can get picky and say that it will look like it is only approaching that limit, but the fact remains that only the light emitted up to a certain point in time (where it leaves our visible universe, but remains in our universe) will ever be able to reach us, it will be stretched over longer and longer periods.
And before someone starts with the argument that nothing can move faster than light, that is not violated. In fact, the far away galaxies are not really moving away, it is the space itself which expands (which looks like distant objects are moving away). If the space between two points expands faster than the speed of light, it only means that no information can be exchanged between those two points, i.e. they don't belong to the same visible universe anymore (but that was likely the case earlier in time).

That all may sound confusing first, but after thinking a bit, it started to make some sense.
17) Message boards : MilkyWay@home Science : Is it posible that the universe are colapsing at this very moment? (Message 40473)
Posted 17 Jun 2010 by Cluster Physik
Post:
Did God tell you there was no medium into which our universe came into existence?

There is no god. He told me! ;)

Explain to me what the universe is expanding into...that is, the event horizon of the universe. What's on the other side of the wall? Strings? Angels? Ahhh, i've got it, nothing! The universe is growing into nothing.

You are making the common mistake of trying to look at the universe from the outside. But this doesn't make any sense as a hypothetical observer outside would be completely disconnected from our spacetime inside (remember the hypothetical vaccum fluctuation which inside growed into our universe while it simply disappered in the other spacetime?). You can only look at the universe from the inside. If you see our universe, you are in our universe. Otherwise it wouldn't be a universe (hint: think what universe means).

So, it started infinitely small, surrounded by....nothing. Grew to the size of a pea, compared to what? There is no frame of reference as there is nothing.

Correct. That is why you can't measure a universe from the outside ;) See above. There is a reason I wrote that there is not even an outside.

Why is the expansion not uniform? what's stopping it from expanding uniformly? What "outside" force is opposing it? Certainly can't be gravity from the inside, it's too weak.

What do you mean with uniform?
Expansion is at least almost isotropic. One thinks that only some random fluctuations in the early universe disturbed it a very tiny amount. One needed great efforts to measure the anisotropy of the cosmic background for instance (which is a direct consequence of the expansion).
And how do you come to the conclusion that gravitation is far to weak to influence the expansion? There is experimental evidence for about 27% of the mass needed to asymptotically stop the expansion. The open question is if we find the missing 73% or if those are comprised of the still hypothetical dark energy.
18) Message boards : MilkyWay@home Science : Is it posible that the universe are colapsing at this very moment? (Message 40471)
Posted 17 Jun 2010 by Cluster Physik
Post:
And the fish in the water swims around casually believing water is the only world there is. Just keep swimming.

But the fish *could* detect that there is more. And the world outside his lake/ocean influences his world, so there is some causal connection.
It is a bit different with our universe where nothing outside can influence our universe. That is identical to say that there is nothing outside.

That's all very well to have your own opinion. As all the mathematicians must be playing a fun game with M-theory. Seems like an awful lot of funding for a mathematical game, wouldn't you say?

Yes ;)

And if Wiki is your source of info, please find a more serious, scientific one. The people who correct/quote/contribute are all on board with mainstream science and have little time for others who wish to challenge their view.

Uhmm, what would it help if I cite the original work of Andrej Linde who "invented" the buble universum. I just had a look to his publications (in real scientific journals if you mind) an he writes specifically of "causally disconnected regions of the universe". That's basically the same as I cited from Wikipedia and he even states that those bubbles are only subregions of our universe. Your point was what?

The philosophy you are invoking is the God theory i believe. In the beginning.....

I don't see where God entered the discussion. I definitely didn't throw him to the conversation ;)

What I know as "God theory" is quite rubbish in my opinion. There is nothing what can't be "explained" (it's actually not an explanation, just a stating of basic facts with very simple logic) with the (weak) anthropic principle.
19) Message boards : MilkyWay@home Science : Is it posible that the universe are colapsing at this very moment? (Message 40466)
Posted 17 Jun 2010 by Cluster Physik
Post:
Ok, i define our universe as the "bubble universe" theory. Convenient, isn't it? Nice theory also.

What's the bubble forming in?

Want to not discuss it as it doesn't fit your theory? Easier to ignore than put a hypothesis forward?

It's just as philisophical as dark energy. 'We think something is accelerating the universe, so it must be inside'. That's kind of ignoring any other opinion, as it doesn't fit yours.

Not at all!

But first, the whole "bubble universe theory" is currently nothing more than a game with some advanced mathematics, it is not substantiated by any experimental/observation data (opposed to the dark energy stuff, there is some evidence for that).

And the second point comes straight from Wikipedia:

The bubble universe model proposes that different regions of this inflationary universe (termed a multiverse) decayed to a true vacuum state at different times, with decaying regions corresponding to “sub”- universes not in causal contact with each other

The bold part simply says that it is impossible to detect, if there is anything. Occams Razor tells me that there is nothing (at it is the simpler alternative and you can't tell the difference). Actually it fits very well with my definition that everything that can have an influence on our universe belongs to our universe. Or in more physical terms: a universe is not only a closed system, it is an isolated system.

Edit:
I believe the fate of the universe depends solely upon the medium into which it was born, big-banged. Blow up a balloon real fast, a huge influx of energy. What happens to it depends upon the pressures outside it.

Important difference is that our universe didn't pop up in some place or in some environment. The whole big bang happens inside our universe.

If there is anything outside (Caution! Heavy unfounded speculation which doesn't matter anyway because it does not influence our universe follows.) it may very well be that our universe is just a vacuum fluctuation in another universe where a tiny black hole with Planck mass und Planck radius was formed just by chance and disappeared again from this other universe within the Planck time (<10^-43 seconds) to conserve energy. And within this randomly created and immediately destroyed tiny thing our own universe develops completely disconnected from its origin with its own spacetime and billions of galaxies. Isn't that a beautiful thought?
20) Message boards : MilkyWay@home Science : Is it posible that the universe are colapsing at this very moment? (Message 40464)
Posted 17 Jun 2010 by Cluster Physik
Post:
I read somewhere, that by recent long-term CMB observations and measurements, it has been concluded that after all our universe seems to be flat instead of open. So it might be that your (and mine) feeling might not be far off.

Actually there is some reasoning that the universe should have a flat geometry and I like the idea a lot. Problem is we can't see that much of matter/energy. That's were the dark energy comes into the game. It is supposed to close the gap to the flat universe. But at the same time it needs to have repulsive properties leading to an accelerated expansion even with a flat universe. And that is what I don't like.

My reasoning in support of non-open universe goes somewhat along this line: the further out we look, we see further back in time. And we see redshift. To me that redshift means nothing more than a fact that things we observe moved at such speeds relative to us at THAT time, not NOW. And since doppler effect (blue/redshift) is a function of speed, is as such invariant to distance, so, if our universe was indeed accelerating in expansion, we should see a lot more redshift closer to us than further out.

And that is exactly how the accelerated expansion was measured. They took a certain type of supernovae known to have always the same absolute brightness (so the apparent brightness we see on earth gives us the distance at some time in the past) and compared it with the redshift.
But as those measurements aren't particularly easy (and some assumptions need to be fullfilled for the method to be working), I'm still not completely convinced (even as there is some solid evidence).

And not wanting to become a victim of Dunning�Kruger effect, I am fully aware that my knowledge in this area is far from perfect, I just wanted to present my line thinking about this question.

Hey, I'm also not an expert in this field (even as I'm a physicist, but I'm doing something completely different). So a lot of my "knowledge" qualifies more as hearsay and handwaving as I heard the lectures about some of the topics years ago and forgot almost everything in the meantime ;)


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