The world around us is full of fascinating objects. But through our senses we cannot fully perceive everything in this universe. And human evolution has been founded on a strong basis of imagination and curiosity. We were always curious about things and so we could evolve to such a magnificent species (with some drawbacks too). Among the magnificent things around us, there is a tiny world, the world with which we are made of, but barely understand it~ The QUANTUM WORLD. This world is like a crazy mess and the more we dive deep into it, the more we know how little we know about ourselves. This paper of mine will be primarily focused on a particular behavior of a particle in this Quantum World, i.e. the MESONS. The said behavior is termed as MESON PARADOX.
WHAT ARE MESONS?
Mesons are subatomic particles made up of one quark and one anti-quark. Mesons are sensitive to the strong force, the fundamental interaction that binds the components of the nucleus by governing the behavior of their constituent quarks. Predicted theoretically in 1935 by the Japanese physicist Yukawa Hideki, the existence of mesons was confirmed in 1947 by a team led by the English physicist Cecil Frank Powell with the discovery of the pi-meson (pion) in cosmic-ray particle interactions. Mesons are very unstable and only a few lasts long enough to be detected by a particle detector, which in turn makes it helpful for the researchers to study the motions of quarks.
Note:- Mesons also provide a means of identifying new quarks. The J/psi particle, discovered independently in 1974, proved to be a meson made up of a charm quark and its antiquark. (Up to this time, three quark types had been postulated—up, down, and strange). It was the first manifestation of charm, a new quantum number the existence of which implies that quarks are related in pairs. The subsequent discovery of another heavy meson, called upsilon, revealed the existence of the bottom quark and its accompanying antiquark and gave rise to speculation about the existence of a companion particle, the top quark. This sixth quark type, or “flavour”, was discovered in 1995. Conclusive proof of its existence culminated the search for one of the last missing pieces in the Standard Model of particle physics, which describes the fundamental particles and their interactions.
WHERE ARE THE MESONS FOUND???
Mesons are typically formed when quarks/antiquarks are involved in collisions. If one quark is impelled away from the other particles, QCD colour confinement(Color confinement, often simply called confinement, is the phenomenon that color charged particles, such as quarks cannot be isolated singularly, and therefore cannot be directly observed, below a critical temperature known as the Hagedorn temperature. Quarks, by default, clump together to form groups, or hadrons. The two types of hadrons are the mesons and baryons) prevents its escape. As the quark tries to escape, the strength of the colour force between the quark and the remaining particles (of net opposite colour) does not decay by the inverse square law, but rather is believed to remain approximately constant. After a very short time, therefore, sufficient work will have been done against the strong attraction to enable a new quark/antiquark pair to be promoted from the vacuum. The anti-quark will have the opposite colour to the originally impelled quark so their colours now add up to zero and hence they can, finally, escape from the other particles. But the newly created quark and anti-quark may or may not be the same flavour as the original quark. Just as Bohr said, “God plays dice”.
Mesons are mostly found in almost everywhere, but due to more proton-proton collisions in upper atmosphere than in lower atmosphere, mesons are found in more concentration in about 800 meters above sea level than at sea level.
Some types of Mesons
These are a few of hundred types of mesons!
THE MESON PARADOX
INTRODUCTION
It is found that there is a far higher amount of proton-proton collisions in the upper atmosphere than at the sea level which is almost negligible. So, one expects to find more mesons in the upper atmosphere than that at the sea level. So it has been detected that at about 2000 meters above sea level, on average of 568 mesons per hour is observed generally. The half-life of mesons is 2.2 microseconds. With a speed close to light, the mesons need approximately 6.6 microseconds to reach sea level. So, at sea level it is expected that (18)th times of what found in 2000 meter above sea level i.e. 71 mesons per hour. But, unexpectedly the number of mesons measured here is 412, almost 6 times the expected number. So, this is the paradox, how did this extra mesons come from, while mathematics suggests that only 71 mesons can be detected in one hour but practically we find a lot more mesons. So, does the mesons do travel faster than light to make their way to the sea level before their time runs out, which is actually prohibited, according to the law of nature, which says “Thou shall not move faster than Light”. So probably we are approaching a wrong path of mathematics, or, perhaps we are missing some physics in it. The answer lies in EINSTEIN’S THEORY OF RELATIVITY- TIME DILATION.
TIME-DILATION
The time dilation phenomenon describes the observation that a fast moving unstable particle seems to exist longer than the same particle at rest. In simpler terms, time for a moving particle moves slow than a stationary particle.
T=t01-v2c2
Where T = Time observed in the moving frame of the reference
t0 = Time observed in the rest frame of the reference
v = The speed of moving object
c = The speed of light in a vacuum
SOLVING MESON PARADOX BY TIME-DILATION APPROACH
Mesons move at a speed that is very close to the speed of light. Now, let the speed of their motion be called ‘u’ which is almost equal to ‘c’
It is known that, from the Time Dilation formula stated above,
T= t01-u2c2
∴As, u→c
u2c2→ c2c2=1
T→infinity
Which means, as the speed of mesons grow, the time for them to reach their half life seems to increases. Due to this we now know the reason why we find so many mesons at the sea level than expected. That is because, from and observer’s frame of reference, the time for the mesons to reach their half life span has slowed down.
CONCLUSION
The Meson Paradox is a basic example of how much true Einstein’s theory of Relativity is. It is a practical proof of his work. Also it opens a new world to us. We can now imagine Quantum Physics, the physics of the small (Mesons) and Theory of Relativity, the physics of big together. This and other stuffs like this can be used as an inspiration for other things like searching for a Grand Unified Theory. Scientists have been working on it since the days of Einstein, and it might be the last chapter on physics.
ACKNOWLEDGEMENT
I would like to thank my professor Shree Shibshankar Nandy, for motivating me for reading and knowing more stuff like this. The topic was completely his idea, when I asked him earlier about a topic I was searching to write something about. Without him, I might not have known anything about Meson Paradox. I would also like to thank the following sources:
The Feynman Lectures on Physics (This always helps me out to understand concepts easier)
Soumya Sarkar
Calcutta University
Physics Department, 2nd Year
Facebook.com/Soumya.Sarkar.750