Addition of velocities in the Newtonian physics. v= speed of the train measured from the platform. w 2 =man’s speed measured from the platform. w 1 =man’s speed measured from the train. w 2 =v+w 1. V. w 1.
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v= speed of the train measured from the platform
w2=man’s speed measured from the platform
w1=man’s speed measured
from the train
If atorch is switched on on the train, from platform we should measure the speed of light as
where v is the train speed and c is light speed from the train
the man on the platform measures the same light speed from the train
the Newtonian physics laws are not valid any more
So, we need another rule to add velocities
In 1968 professor Bertozzi used the linear accelerator of the MIT to verify Einstein’s Theories.
Bertozzi used the accelerator to accelerate clusters of electrons. According to the Newtonian physics the speed of electrons should proportionally increase as we add energy without any limit
Instead of following a linear progression the experimental graphic turned out to be like this:
Speed of electrons
Electrons kinetic energy
Once again Newtonian physics is not valid
Muons are subnuclear particles which are created by interaction of cosmic rays with high atmosphere
Muon average lifetime as measured in laboratory is 2,2x10-6s, we’ll call it t.
After their creation, muons run toward the earth at 0,995 c
Since muons are created at 5000m from earth surface, with a simple
computation we find out that they can’t reach the earth:
0,995c x (2x10-5s)= 657m
But we detect them on the earth!
Einstein gives us the answer to this problem.
In Einstein’s physics time is not absolute: every time evaluation must be referred to a specific observer.
Muons lifetime is actually longer than t.
Basing on the value measured in laboratory, we obtain the muon lifetime following this equation
Now, let’s apply Einstein’s theory to the muon problem:
2.20x 10-6 s
t‘= = 2,20x10-5 s
Now muons can reach the earth
Anyway, Newtonian physics is still valid and useful in many situations in everyday life.
Relativistic effects are not measurable at everyday speed.
For example, travelling on the Space Shuttle, nowadays the fastest human vehicle, at 28000 km/h:
Time delay per second is
only 0,000000000333 s.
So, a clock positioned on the shuttle will be one second late in 100 years
Supervision: Prof. Barbara Ranco