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Profile Benjamin Wandelt
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Message 4162 - Posted: 5 Dec 2007, 17:59:03 UTC

Hi all -

Here is a question for you: did anyone look at the Pico website or paper?

Ben
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Message 4165 - Posted: 5 Dec 2007, 21:20:16 UTC

I looked at it Ben but it\'s all pretty much over my Head, I\'m just a simple retired factory worker so all that rocket science stuff is a little out of my league ... :)
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Message 4167 - Posted: 5 Dec 2007, 22:20:11 UTC - in response to Message 4162.  

Ben, I have looked at the website and the paper but the info is too technical for me to understand. I suggest that every announcement on the project website will have two identical reports. The first will be technical for those inclined and the second will be general for the public at large. I hope this is feasible!
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Message 4168 - Posted: 5 Dec 2007, 22:21:57 UTC

Ben,

The layout and the substance of the web page looks great for as much as I could understand. How much usage by scientists do you expect?

Regards-Jeff
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Message 4169 - Posted: 5 Dec 2007, 22:29:01 UTC

I had a look as well. I agree that for people who are not up to speed on the subject matter, the article is over their (I should really say *our*) head. Still, scanning through the text and jumping over formulas, I understand that the research has lead to vast improvements in calculation speed, which is great news.

I also saw the section with the references to typical participants. Congratz to those of you who got mentioned. ;)

BOINC.BE: For Belgians who love the smell of glowing red cpu's in the morning
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Message 4173 - Posted: 5 Dec 2007, 23:43:54 UTC

Is there a version in English? You know, small words and short sentences...
In the beginning, there was nothing, which exploded.
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Message 4174 - Posted: 6 Dec 2007, 0:02:25 UTC

Hi -

Some replies and further comments:

Yes, the paper itself is written for specialists. But I still thought it\'d be fun for you to see the first fruit of your contributions. Sorry about the long sentences and words! There is actually someone here at the University whose job it is to make sure all the scientists write in ways that are impossible to understand - and he was standing right next to us as we were working on the paper... :) Just kidding... but it\'s much harder to write in a way that everybody can follow and that\'s still true and precise enough...

How much usage by other scientists do we expect? The first version of Pico was downloaded by around 150 people, which is quite a large number - there aren\'t that many cosmologist in the world (unless we start counting all of you!). The Planck space project will most likely use Pico to do its parameter estimation.

The main point of the paper is that with cosmology at home we could make Pico much more accurate. The paper shows examples of that.

As I said in the news post: Pico is like speed in a bottle. Pico can extract the essence out of all the work units your computers have crunched. Then Pico can apply the knowledge gained to do the same calculation, just 250,000 times more quickly.

All the plots in the paper basically show that Pico is now the most accurate fast code in the world to match cosmological models with observations - all thanks to Cosmology@Home!

The figure on the pico website actually shows the current best representation of what we know about the cosmological parameters. The plots on the diagonal of this matrix show the ranges of these parameters that are allowed by the data.

Most of the cosmological parameters shown there are described in the short description of the cosmological parameters under \"cosmic background\" on my home page.

You can find an overview of the idea Pico that is at least intended to be accessible for non-specialists in the same place. I also put some more information on the Wikipedia article.

If you find things anywhere on the explore pages of my site that are too difficult to understand let me know. I will eventually try to make it easier to understand. Your feedback really helps!

All the best,

Ben

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Message 4175 - Posted: 6 Dec 2007, 0:09:44 UTC - in response to Message 4173.  

Is there a version in English? You know, small words and short sentences...


LOL ... :)
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Message 4176 - Posted: 6 Dec 2007, 0:23:34 UTC - in response to Message 4174.  
Last modified: 6 Dec 2007, 0:26:38 UTC

snip
How much usage by other scientists do we expect? The first version of Pico was downloaded by around 150 people, which is quite a large number - there aren\'t that many cosmologist in the world (unless we start counting all of you!). The Planck space project will most likely use Pico to do its parameter estimation.



Maybe a lot of grad students want a masters or doctorate in Cosmology :)
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Message 4179 - Posted: 6 Dec 2007, 2:49:45 UTC

I read it Ben, well most of it, and the gain is speed you will get from this application is remarkable. Most people are impressed with an increase of 5 to 10 times, but thousands of times faster is really excellent.

From what I understood, we will be able to do a huge amount of data processing in the same time frame, this will really help with getting things done faster and therefore results getting coming on line much quicker. This will make the universities happier too as they will be seeing results and know why they run the science projects that they do.
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Message 4181 - Posted: 6 Dec 2007, 5:06:47 UTC

I looked at the paper the first day you mentioned it. It was definately not for the average person (me included). What I understood was that because of our work, other work can be done much faster. That excellent. However, what exactly are we doing right now? Will the current/future WUs be able to speed things up even more or are the WUs going to change somehow and help in a different way? Will future WUs somehow use this PICO in some way?

Anyway feel free to use my name in the next paper ;)
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Message 4182 - Posted: 6 Dec 2007, 5:34:04 UTC

Acmefrog -

We are changing the WUs to explore different model classes. So far we have varied 9 parameters. This is already more detailed than some other treatments and that\'s what we have made available with Pico but we are planning to go beyond that.

In the future we could look at several more effects that add more variables/parameters to the model. For example, by comparing these models to the data we would learn more about the detailed properties of dark energy. Another way to make the models more detailed is to look for ways to distinguish the three neutrino species (electron, muon and tau neutrino) individually, rather than treating them as a single overall neutrino fluid.

Another item on our to-do list for the intermediate term is to apply C@H to new types of problems. Here we have some definite ideas but there is still some work to do to turn the existing research codes into executables that will run sensibly in C@H, e.g. using readily available libraries without licensing issues.

This probably more detail than you wanted, but your questions are a good opportunity to share my thinking with everyone here... :)

All the best,
Ben

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Message 4190 - Posted: 6 Dec 2007, 15:33:11 UTC

Hi Ben,

The science you are doing is way over my head. However, I\'m satisfied to lend my unused computer cycles to your project.
I scanned through the paper, again over my head. I was gratified to see that \"our\" contributions were acknowledged.

Frank B
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Message 4191 - Posted: 6 Dec 2007, 17:37:09 UTC

Ben-

Thanks for the glimpse into the future. It provides a good sence of what and where we are going with Cosmo.

Thanks for the info.

Cheers!
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Message 4192 - Posted: 6 Dec 2007, 21:46:35 UTC - in response to Message 4182.  



We are changing the WUs to explore different model classes. So far we have varied 9 parameters. This is already more detailed than some other treatments and that\'s what we have made available with Pico but we are planning to go beyond that.

In the future we could look at several more effects that add more variables/parameters to the model. For example, by comparing these models to the data we would learn more about the detailed properties of dark energy. Another way to make the models more detailed is to look for ways to distinguish the three neutrino species (electron, muon and tau neutrino) individually, rather than treating them as a single overall neutrino fluid.

Another item on our to-do list for the intermediate term is to apply C@H to new types of problems. Here we have some definite ideas but there is still some work to do to turn the existing research codes into executables that will run sensibly in C@H, e.g. using readily available libraries without licensing issues.



This is good news! I have a general understanding of what is going on here. The number and combination of parameters in exploring what is possible with our universe seems almost unlimited! How long will this project take in finding the one final set of parameters that matches closest to our universe? It will be very interesting to find out.
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Message 4193 - Posted: 6 Dec 2007, 22:48:49 UTC

Greetings,

An interesting paper!

Professor Wandelt would you be kind enough to provide operational definitions of the parameters listed in Table 1 of the paper that are not given at your home page: namely Omega_k, theta, and tau?

Also some working definition of the WMAP likelihood would be enlightening. I think I already understand the importance of the power spectrum from the comments at your home page.

Best regards,
EigenState
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Message 4214 - Posted: 9 Dec 2007, 0:31:21 UTC - in response to Message 4193.  

Greetings,

An interesting paper!

Professor Wandelt would you be kind enough to provide operational definitions of the parameters listed in Table 1 of the paper that are not given at your home page: namely Omega_k, theta, and tau?

Also some working definition of the WMAP likelihood would be enlightening. I think I already understand the importance of the power spectrum from the comments at your home page.

Best regards,
EigenState


Sure:

Omega_k determines the curvature of the Universe. it\'s related to Omega_total, the sum of the contributions from all forms of matter and energy.
Omega_total=1-Omega_k .
If Omega_total is 1 the Universe has flat geometry and Omega_k=0. Omega_k<0 means the Universe has positive curvature (sphere-like) and Omega_k>0 means negative curvature (saddle-shaped).

theta is basically the angle subtended by the typical distance between spots in the CMB. Technically it\'s the angle subtended by the sound horizon (the distance sound waves could travel in the primordial plasma since the Big Bang) at the time the CMB was emitted. Measuring theta and Omega_k gives us important information about the size and age of the Universe.

tau is the \"optical depth.\" This means tau measures the probability that a CMB photon scatters off of an electron on its long way from the early Universe to us. These electrons are produced by energetic ultraviolet radiation due to the first stars, so measuring tau gives us unique (if indirect) information about the first population of stars. These first stars are just too far away to be seen with any of the telescopes we have.

All the best,
Ben

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Message 4217 - Posted: 9 Dec 2007, 1:08:27 UTC

Thank you!
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Forums : Cosmology and Astronomy : Comments on Pico?