What we discussed in the last post are well known phenomenon called length contraction and time dilation.
Briefly summarized, length contraction means that object would be shorter to a person who is moving with respect to the object, when compared with the person who is stationary with the object. Similarly, a stopwatch held by a person will run slower as seen by a person who is moving with respect to the person holding the watch.
Therefore, the same object can have different lengths for different observers, and even the same time interval can be different to different observers, as long as the observers are moving with respect to each other.
As discussed previously, it really seems to indicate that everything is relative and absolute truth is only an illusion. Is that correct?
My favorite experimental fact to recall on Special Relativity is the muon experiment. Muons are particles created when cosmic rays hit the top of the Earth’s atmosphere. They have very short half-life, and they disintegrate very quickly after their formation. Even though they travel at an enormous speed, a simple calculation using the formula that "time is equal to distance divided by speed" shows that most of the muons created in the upper atmosphere cannot survive long enough to reach the ground. However, that is not what we found.
From our perspective, muons have very short half-life. However, the half-life is measured by people working in stationary labs on Earth. Because of time dilation, muons’ clock runs much slower than ours. As a result, their half-life with respect to Earth is actually several times longer than we thought.
From the muons’ perspective, they would not find their clocks running slower than normal. They find that they have the same half-life as we measured in our labs. However, they see distance much shorter than us on Earth because of length contraction. To the muons, the distance they have to travel to reach the ground is much shorter than what we thought they need to.
What is the end result? A lot more muons reach the ground than we expected. Why? From our perspective, the muons have a much longer half-life than they should because of time dilation. Therefore, they have more time to fly and so they reach further down to Earth. From the muons’ perspective, the distance to travel from the upper atmosphere to ground is much shorter than we measured. Even though they have short half-life, it is long enough to travel the short distance to the ground.
Muons and we do not agree on their half-life, neither do muons and we agree on the distance they have to travel to reach the ground. However, there is one undeniable fact that muons and we agree: a lot more of them can reach the ground than our simple calculation shows!
We may not agree on even the most basic things in life: distance and time. However, reality and truth are still there, disregard of different perspectives.
Friends, I have been discussing reality and truth with examples from our physical environment so far. Do we have absolute truth in morality and ethics? That I will discuss in later posts.
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