

Should we worry about what the LHC is not finding? - mrsebastian
http://www.newscientist.com/article/dn20729-should-we-worry-about-what-the-lhc-is-not-finding.html?DCMP=OTC-rss&nsref=online-news

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jameskilton
On the contrary, I remember a quote from some physicist before LHC went live
saying something like "if the LHC finds nothing that we've been predicting
that will be a more incredible find (than proving the Higgs or Graviton),
because that means we're completely wrong".

The LHC not finding particles in the areas we're predicting is simply telling
us that our predictions were wrong. Time will tell, the LHC is still
relatively new and is producing a metric ton of data. What we find in the next
few years will radically change our understanding of the cosmos, I'm sure.

~~~
jpallen
If the LHC finds nothing it would be interesting but I don't think it would be
a good step forward for physics. Of course any step in the right direction is
good, but we would have no where to specifically look, and have just blown a
lot of funding with no results to show off during the next round of funding.

A much better outcome would be to find something exotic that can spark
research in the right direction. At the moment we have many ideas past the
standard model but no way to know which to pursue with any seriousness.

Of course, discussion of what would be good or bad doesn't matter much. It
will find what it finds (or doesn't)

~~~
felipemnoa
>>and have just blown a lot of funding with no results to show off during the
next round of funding

On the contrary, now we can stop wasting man hours on incorrect theorems and
start looking for the right ones. This is really interesting because it means
that the universe is much different than we imagined.

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Ronkdar
Data not backing up hypothesis is not cause for worry. That's just part of
science, and the result is still valuable.

The fact that no gravitons have been found below 2 TeV is data from which
useful conclusions can be drawn about their nature, if they do exist.

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kamagmar
Standard gravitons are already constrained to be almost massless, so i'm
guessing the article is referring to Randall-Sundrum type massive gravitons in
5D.

~~~
jessriedel
Why does their detectability depend on the mass? My understanding is that both
the standard and Randall-Sundrum gravitons can only be identified through
missing energy; neither are possible to directly detect through any feasible
experiment. Does the low upper bound on the mass constrain the cross-section?

~~~
kamagmar
I believe the main RS discovery channel is looking for a p pbar -> graviton ->
e+ e- resonance, where p is a parton (i.e., quark or gluon).

~~~
jessriedel
Is the following reasoning correct? If the standard graviton is massless, it
can't decay into r rbar for any particle r (because of momentum conservation).
The standard graviton could have a tiny mass, but the low upper bounds on it
means that the cross section is too tiny to be observed. RS gets around this
because at LHC energies the RS graviton has a larger high-energy effective
mass (because of extra dimesions) while still satisfying the low-energy
experimental mass limits.

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powertower
> At the same time, there is no sign yet of gravitons particles that transmit
> gravity and are essential...

I never understood how you can explain gravity as 1) a bending of space-time
caused by mass and then 2) pretend it's a force transmited by "gravitons".

If 1) is true then it's an effect (phenomena), not a cause (force). If 2) is
true than it's a cause (force), not an effect (phenomena).

~~~
alphaBetaGamma
The way physicists understand this is that the curved space-time view of
gravity is an approximation that is only valid when you have a lot of
gravitons. In that situation you do not see individual gravitons but only the
aggregate effect of the ‘sea’ of gravitons you are in.

This is similar to e.g. fluid dynamics, which is only valid at scales much
larger than the atomic scale. But if you look close enough, you will see
effects that are not consistent with viewing a fluid as a continuum of matter
(e.g. minute specks of dust moving randomly because they are hit by individual
atoms).

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hammock
Gravitons are the kookiest theoretical particle I have ever heard of. I had an
intuition that they were kooky and contrived when I first heard of them as a
child, and now that I know more about them and gravity, I have even more
disbelief in them. Why people still believe in them I will never know.

Here's the latest thing I have seen, btw: <http://arxiv.org/abs/1001.0785> Pop
science interpretation of it:
<http://www.nytimes.com/2010/07/13/science/13gravity.html>

~~~
starwed
You know what I'll never know? Why people think they know better than the
scientific community after reading a few pop science articles.

If you have a single issue with gravitons that can be expressed
_mathematically_ , show us.

~~~
hammock
I didn't say I knew better than "the scientific community" (whomever they are,
since there is not a huge amount of consensus around gravitons), I just said I
have a lot of doubts. I could be wrong.

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stcredzero
The picture in the article is eerily reminiscent of scenes from certain
movies. (Probably because of the rule of thirds, and the left-to-right
directional bias of western audiences.)

<http://www.firsttvdrama.com/funstuff/tarkin/dsgun.jpg>

[http://www.starwars.com/img/theclonewars/guide/episode002/il...](http://www.starwars.com/img/theclonewars/guide/episode002/illo01.jpg)

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ristretto
That's actually good news; I mean, it reminds the Michelson-Morley experiment,
right?

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phyllotaxis
_EDIT_ \- WHY IS THIS STATEMENT DOWNVOTED? REALLY?

There are huge flaws in the art as it is practiced today. They aren't finding
what they're looking for because it IS NOT THERE. Go to the following site,
and understand the gap between the fantastic but invented idea-chasers that
are currently en vogue, and the scientists that are taking measurements and
fitting the results to known phenomena.

This will change your view of modern science forever, and I humbly assert that
it _should_.

<http://www.electric-cosmos.org/indexOLD.htm>

~~~
scarmig
"When confronted by observations that cast doubt on the validity of their
theories, astrophysicists have circled their wagons and conjured up pseudo-
scientific invisible entities such as neutron stars, weakly interacting
massive particles, strange energy, and black holes. When confronted by solid
evidence such as Halton Arp's photographs that contradict the Big Bang Theory,
their response is to refuse him access to any major telescope in the U.S."

Uh huh.

