Muons are short-lived subatomic particles that can be produced in accelerators or when cosmic rays hit the upper atmosphere. A muon at rest has a lifetime of 2.2 microseconds. Muons produced in the upper atmosphere travel at nearly the speed of

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Muons are short-lived subatomic particles that
can be produced in accelerators or when cosmic
rays hit the upper atmosphere. A muon at rest
has a lifetime of 2.2 microseconds. Muons
produced in the upper atmosphere travel at nearly
the speed of light, so they have a much longer
lifetime. (Their clocks run slowly.)
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Muons produced in the upper atmosphere travel at
nearly the speed of light, so they have a much
longer lifetime. (Their clocks run
slowly.)Suppose we have synchronized clocks at
the top and the bottom of the atmosphere. We
start the clocks when the muon is created, and we
stop them when it decays, which happens in this
case to be at the bottom of the atmosphere.
What does the muon see?
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What does the muon see?A Since its moving and
our clocks are not, it sees our clocks running
fastB It sees our clocks running slowly, but
it disagrees with us about the reading on the
bottom clock (only) when it decaysC It sees
our clocks running slowly, but it observes that
the top clock is ahead of where it should be for
proper calibration D It sees our clocks
running slowly, but it observes that the top
clock is behind where it should be for proper
calibration. E It sees our clocks running
slowly, but disagrees with us about the readings
on both clocks as it passes/decaysF Muons
dont have eyes or brains, so it cant see or
think anything.
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Signals cant travel faster than
cCalibration Lorentz Transformation
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Two supernovas AB are equidistant from the earth
in opposite directions, and stationary wrt
earth.They explode at the same time, according
to an earth observer. (She sees the flashes of
light at the same time.)An observer in an
airplane flying toward B willA see the flash
of light from A firstB see the flash of light
from B firstC will see the flashes at the same
time
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C The observer will ALSO see the flashes at
the same time. These events all happen in the
same place and at at same time, so they are
simultaneous for all observers.To the observer
on the airplane, how do the distances (at the
moment the flashes are observed) compare?A A
is closer at this instantB B is closer at this
instantC AB are equidistant when the flashes
are seen
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The plane is flying toward B, away from A.C
The supernova are equidistant at the time the
flashes are seen. (The distance to each is less
than according to the earthbound observer,
however.)Since the flashes are seen by the
plane rider to be simultaneous, and the SN are
equidistant at the time of observation, what does
the plane rider conclude?A SN A must have
occurred earlier than SN BB SN B must have
occurred earlier than SN AC The two SN were
simultaneous.
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The plane is flying toward B, away from
A.Although the flashes are seen simultaneously,
and the SNs were equidistant when the flashes
were seen, the observer knows that, in the past,
B was farther away than A. If B was farther
away when it emitted its flash, it must have done
so earlier in time. (That light had farther to
go!)Lets draw a Minkowski diagram.