Comments on: Questions for Cosmologists http://www.math.columbia.edu/~woit/wordpress/?p=4 Tue, 24 Nov 2009 05:18:29 -0500 http://wordpress.org/?v=2.8.6 hourly 1 By: Gary http://www.math.columbia.edu/~woit/wordpress/?p=4&cpage=1#comment-41 Gary Wed, 31 Dec 1969 19:00:00 +0000 http://www.math.columbia.edu/~woit/wordpress/?p=4#comment-41 Who can really know for a certainty where future CMB research will lead (if but to answer the aforementioned question regarding the extraction of the GUT scale from CMB data.) We will just have to wait and see. But I will tell you this much, that when we do hopefully we'll be smart enough to recognize a designer involved in the greater scheme of creation, and not the theories themselves. Who can really know for a certainty where future CMB research will lead (if but to answer the aforementioned question regarding the extraction of the GUT scale from CMB data.) We will just have to wait and see. But I will tell you this much, that when we do hopefully we’ll be smart enough to recognize a designer involved in the greater scheme of creation, and not the theories themselves.

]]> By: Alexander Crawford http://www.math.columbia.edu/~woit/wordpress/?p=4&cpage=1#comment-42 Alexander Crawford Wed, 31 Dec 1969 19:00:00 +0000 http://www.math.columbia.edu/~woit/wordpress/?p=4#comment-42 However interesting the statistical/mathematical models may or may not be, the actual difficulties aren't addressed very seriously in terms of experimental problems or circuit design methods (errrr... the standard deviation measure of step rise times from step response to impulse response doesn't suggest "extra-dimensionality" in a physical sense). It'd probably be very interesting for most theoretical physicists to look into the wire spring relay developed by Western Electric and current in the mid-1960's, especially for those interested in String Theory. It might be as interesting as the M-M interferometer design as that relates to other somewhat older cosmological models. The magnetic field model is available at MIT and a couple of other sites (view source option-read comments) for a curious take on m-m data. Regarding the questions specifics... Here's a link to the NIST page for phase noise and metrology: http://www.boulder.nist.gov/timefreq/phase/ Here's the optical frequency measurement group links http://www.boulder.nist.gov/timefreq/ofm/index.html useful glossary: http://www.boulder.nist.gov/timefreq/general/glossary.htm (The USNO has a very comprehensive library of technical papers for the serious.) However interesting the statistical/mathematical models may or may not be, the actual difficulties aren’t addressed very seriously in terms of experimental problems or circuit design methods (errrr… the standard deviation measure of step rise times from step response to impulse response doesn’t suggest “extra-dimensionality” in a physical sense).

It’d probably be very interesting for most theoretical physicists to look into the wire spring relay developed by Western Electric and current in the mid-1960’s, especially for those interested in String Theory. It might be as interesting as the M-M interferometer design as that relates to other somewhat older cosmological models. The magnetic field model is available at MIT and a couple of other sites (view source option-read comments) for a curious take on m-m data.

Regarding the questions specifics…

Here’s a link to the NIST page for phase noise and metrology:

http://www.boulder.nist.gov/timefreq/phase/

Here’s the optical frequency measurement group links

http://www.boulder.nist.gov/timefreq/ofm/index.html

useful glossary:

http://www.boulder.nist.gov/timefreq/general/glossary.htm

(The USNO has a very comprehensive library of technical papers for the serious.)

]]> By: Sean http://www.math.columbia.edu/~woit/wordpress/?p=4&cpage=1#comment-43 Sean Wed, 31 Dec 1969 19:00:00 +0000 http://www.math.columbia.edu/~woit/wordpress/?p=4#comment-43 These are very good questions, so much so that I started a multi-part answer over at my blog. Basically, the energy scale of inflation is roughly equal to the Planck scale times the square root of the perturbation amplitude; this works out to be the GUT scale. It's nicely consistent, but by no means direct evidence; Witten was right to say that it's "suggestive," but not more than that. If we were able to measure gravitational-wave modes, that would give a direct measurement of the energy scale. This is only in the simplest models, of course. If you get more baroque you can do whatever you like, including inflation at the electroweak scale. But you have to work at it. Likewise with getting information about Planck-scale effects; it's unlikely, but worth thinking about. We should talk about string cosmology another time. String theory is not a completely well understood theory, but it's not vacuous, either. But string cosmology is in its infancy, to say the least. These are very good questions, so much so that I started a multi-part answer over at my blog. Basically, the energy scale of inflation is roughly equal to the Planck scale times the square root of the perturbation amplitude; this works out to be the GUT scale. It’s nicely consistent, but by no means direct evidence; Witten was right to say that it’s “suggestive,” but not more than that. If we were able to measure gravitational-wave modes, that would give a direct measurement of the energy scale.

This is only in the simplest models, of course. If you get more baroque you can do whatever you like, including inflation at the electroweak scale. But you have to work at it. Likewise with getting information about Planck-scale effects; it’s unlikely, but worth thinking about.

We should talk about string cosmology another time. String theory is not a completely well understood theory, but it’s not vacuous, either. But string cosmology is in its infancy, to say the least.

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