Re: [asa] LHC, TOE, and the limits of knowledge

From: David Clounch <david.clounch@gmail.com>
Date: Sun Sep 14 2008 - 00:40:08 EDT

Iain,

Lisa Randall, in her book on brane theory (Warped Passages) discusses at the
end her paper, the RS2 paper (written with ??Sundstrom??). The RS2
paper apparently proposes some tests which can possibly actually be tested
by the LHC. This would give us an indication of which string theory may be
correct. (Hope I'm not mischaracterizing this Randy).

Its got to do with why we need a collider that has at least 10^16 times
higher energy than (the LHC? than the Higgs boson? I don't remember) in
order to be able to test string theory. But Lisa found a possible way
around that.

I cannot claim I understand everything in the book, and its over 500 pages,
but I'd say its well worth wading through. I especially enjoyed what Lisa
said about the theory of scientific theories and the limits of knowledge.
It jived with my engineering and physics background. Which is something the
ASA discussion on such theories usually doesn't jive with hardly at all.

Best Regards,
Dave Clounch

On Wed, Sep 10, 2008 at 12:47 PM, Iain Strachan <igd.strachan@gmail.com>wrote:

> It's possible my physics is too rusty to make the following speculations
> valid, but I'd be interested to hear what folks think.
>
> Physicists have for a long time talked about the TOE (Theory Of
> Everything), and I wonder if the belief that we are somehow close to a TOE
> is based on atheistic precepts.
>
> Thinking about the LHC and what it hopes to achieve made me think about
> this - and I think it shows possibly that we are always going to run up
> against limits that we'll never be able to explore.
>
> What started me thinking was all the headline stuff about the Big Bang and
> that the LHC is the "Big Bang" experiment; and that it will create
> conditions and energies that were present in the first trillionth of a
> second after the Big Bang. That may seem an incredibly small time, but it
> occurs to me that in physics that is actually an incredibly long time.
>
> So we're talking about the first 10^-12 of a second of a universe that has
> lasted 10^18 seconds - around 30 orders of magnitude longer than this period
> of time.
>
> However, the smallest possible unit of time, as I recall, is the Planck
> time of 10^-43 seconds, which is an even more impressive 31 orders of
> magnitude shorter than a trillionth of a second. So, on a logarithmic scale
> of digging back to the Big Bang, we're not even half-way there!
>
> It's my understanding that Physics changes radically when scales change by
> many orders of magnitude (e.g. 8 orders of magnitude in velocity is required
> for Newton's laws to break down and relativistic effects to come into play).
>
> Hence it seems to me that the next step will likely only peel the next
> layer off the onion - and we have no way of knowing what unanswered
> questions are present in the layers below, or what complex and rich physics
> that we know nothing about took place hidden in those 31 orders of
> magnitude. We would only be able to theorise based on what we know of what
> happened after them.
>
> Since higher energies could only be produced by larger and larger
> accelerators, it seems to me that such knowledge, in the sense of empirical
> verification, will be forever out of our reach. We might build an
> accelerator the size of a country; hardly one the size of the planet, and
> impossible to build one the size of the Solar System, or the galaxy.
>
> Now, perhaps I'm missing some vital piece of modern physics that makes us
> sure that we're near the last layer of the onion and that we WILL have a TOE
> in the near future, but I feel sceptical about this - laws tend to break
> down when velocities, energies are pushed to previously unknown limits.
>
> Iain
>
> --
> -----------
> Non timeo sed caveo
>
> -----------
>

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Received on Sun Sep 14 00:40:49 2008

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