

Why the Z boson had a different mass at different times of day. - jlangenauer
http://en.wikipedia.org/wiki/LEP#Results

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diiq
Theoretical science is certainly romantic --- but this sort of thing is what
makes experimental science sexy. To be able to say "Ah! I am accidentally
measuring the gravitation of the water in a nearby lake" --- and then
_compensate_ for it. Data so sharp you cut yourself.

~~~
tel
I'd love to be the guy who decided _I bet that low frequency monthly term is
the tides, let's just regress it out shall we?_

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diiq
Yeah, surely _someone_ got a free beer out of that one.

I wonder, once you've convinced yourself the idea isn't crazy, how you go
about convincing someone else --- _No, look at the tidal chart, and then look
at this variation here. See?_ And then one day you've hit critical mass and
the whole lab is looking at train tables, the passage of the moon, and how
often yo' momma brings you lunch, trying to find correspondences.

Or maybe there was already a list of possible confabulations, in decending
order, and they checked them off one by one. That would be less amusing, I
think.

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tel
Well, we are talking about the measurements of the Z boson being inaccurate
(at really, really, really high levels of precision), not that the boson
itself is somehow changing mass.

Sounds like a lot of fun to be had with super precise measurements in any
case.

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naveensundar
I think the mass actually changed. If you move, your mass increases w.r.t to
an inertial frame. The closer you travel to the speed of light the more mass
you get. I think mass also changes when the gravitational field changes. The
device picked up those small changes .

<http://en.wikipedia.org/wiki/Mass_in_special_relativity>

~~~
chris_l
According to the quote, the shape of the experiment was changing...

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naveensundar
"So the bigger lake in the Spring was making the particle heavier." I am not
sure which effect the quote describes: a slight change in the mass or a change
in the instrument. Both are different. If it is the former I should be able to
measure the change from light years away (since the lake wont affect me but
will affect the particle).

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Oompa
I wonder why the weight of the boson is affected by all these factors. Anyone
care to fill me in?

~~~
dehowell
Z bosons decay into a lepton (electron, muon, or tau particle) and its anti-
particle. Those decay products pass through a magnetic field and eventually
collide with a material that absorbs all of their energy. Measuring the path
of the leptons (in particular, the deflection caused by the magnetic field)
allows you to determine their momentum. The intensity of the collision with
the stopping material is used to determine the energy.

Knowing the energy and momentum allows one to calculate the path.
Gravitational forces are also acting on those particles, and any changes in
their paths caused will change the final calculated mass.

~~~
Oompa
So it's just the gravitational forces acting on those Z bosons that affect the
measurement of weight? If so, I'm just blown away. Physics never ceases to
make my day better.

~~~
swolchok
At least in my last physics class, weight was defined to be the gravitational
force of the earth acting on an object. Perhaps you're blown away because
you're equating weight and mass?

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TriinT
To be precise, weight is defined as the magnitude of the force one must apply
to an object in a gravitational field in order to hold it at rest.

If you're on the moon, the gravitational force of the earth acting on an
object is not what matters. It's the gravitational force of the moon that
matters.

~~~
Locke1689
They're not measuring weight anyway -- they are measuring mass. Maybe I'll
write up a blog post with a picture of how mass spectrometry works. It's a
fairly common homework problem in intro EM courses anyway.

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teeja
So it wasn't the ghost of Wolfgang Pauli flitting by after all?

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DannoHung
That would pretty much drive me nuts.

I mean, you'd end up having to worry about the migratory patterns of birds and
the pollen index while attempting to lock the actual value down.

~~~
dhughes
Before any of that would be people walking by or int he area of the
experiment, your own body and your changing (increasing?) weight.

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RK
For those interested, the train they were talking about was the French TGV
high-speed train:

<http://en.wikipedia.org/wiki/TGV>

