Understanding Uncertainty Principle

In summary, the uncertainty principle states that it is impossible to simultaneously measure both the position and momentum of a particle with arbitrary precision. This is not due to a limitation in measurement equipment, but rather a fundamental property of quantum mechanics. To measure the momentum of a particle, one can measure its energy or frequency precisely. This can be done by using an ensemble of particles with the same momentum, such as a laser beam, and measuring its frequency through methods such as passing it through a prism. However, these methods are quite technical.
  • #1
mananvpanchal
215
0
Hello All,

I want to understand uncertainty principle.

I understand that when we measure x accurately we cannot measure p with that accuracy.
The process of measuring x accurately might like this: some detector fires high energy photon to that small particle, and we can know x accurately. But the high energy photon can change momentum of the particle.
But, when we fires low energy photon to that particle we get fuzzy region of probability for that particle.

Now, I want to understand how can we get accurate momentum by getting fuzzy region of the particle? What might be the process to get it?
 
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  • #2
Hello, All

Why my question is unanswered? Please, tell me what is wrong in my understanding. Please, correct me if some thing I misunderstood.

Thanks.
 
  • #3
I can't help you with methodology for measurements, but I will point out that the UP is NOT a measurement phenomenon. That is, it is NOT a problem that we just don't have the right kind of measurement equipment, it is that it is impossible, regardless of measurement technique, to get arbitrarily precise measurements of BOTH position and momentum at the same time.

There are many threads on this forum that discuss this. I suggest a forum search.
 
  • #4
phinds said:
I can't help you with methodology for measurements, but I will point out that the UP is NOT a measurement phenomenon. That is, it is NOT a problem that we just don't have the right kind of measurement equipment, it is that it is impossible, regardless of measurement technique, to get arbitrarily precise measurements of BOTH position and momentum at the same time.

There are many threads on this forum that discuss this. I suggest a forum search.

I have searched forum, but I don't get exactly what I want.
I am not talking about measurement phenomenon, or measurement equipment.

My question is: We can determine precise position of a particle, but in this act we change its momentum.
Now, I want to measure momentum precisely, I don't care about preciseness of position now. How can I do that?
 
  • #5
If your particle is a photon, for example, you can measure its momentum precisely by measuring its energy and/or frequency precisely. There are many ways of doing this (for example, pure gases only absorb light of very specific frequencies; you could use this fact to build frequency-sensitive photodetectors).

With things like conventional photodetectors, though, they are already well-localized in space so you can't measure a precise frequency for a single photon. A way to get around this is to use an ensemble of photons, all with the same momentum (e.g. a laser beam) to get a precise frequency. A laser beam is 'smeared' out in one dimension, so a precise frequency can be calculated for it.

Frequency measurements on laser beams are done a variety of ways. One way is to pass the beam through a prism and record the deflection angle. There are more precise ways, of course, but they are a little technical.
 
  • #6
IttyBittyBit said:
If your particle is a photon, for example, you can measure its momentum precisely by measuring its energy and/or frequency precisely. There are many ways of doing this (for example, pure gases only absorb light of very specific frequencies; you could use this fact to build frequency-sensitive photodetectors).

With things like conventional photodetectors, though, they are already well-localized in space so you can't measure a precise frequency for a single photon. A way to get around this is to use an ensemble of photons, all with the same momentum (e.g. a laser beam) to get a precise frequency. A laser beam is 'smeared' out in one dimension, so a precise frequency can be calculated for it.

Frequency measurements on laser beams are done a variety of ways. One way is to pass the beam through a prism and record the deflection angle. There are more precise ways, of course, but they are a little technical.

Thanks IttyBittyBit.
 

FAQ: Understanding Uncertainty Principle

What is the Uncertainty Principle?

The Uncertainty Principle, also known as Heisenberg's Uncertainty Principle, is a fundamental principle in quantum mechanics that states that the more precisely we know the position of a particle, the less precisely we can know its momentum, and vice versa. In other words, there is a limit to how precisely we can measure both the position and momentum of a particle at the same time.

Who discovered the Uncertainty Principle?

The Uncertainty Principle was first proposed by German physicist Werner Heisenberg in 1927. He was trying to explain the behavior of subatomic particles and their dual nature as both particles and waves. Heisenberg's work revolutionized the field of quantum mechanics and has had a profound impact on our understanding of the physical world.

How does the Uncertainty Principle affect our daily lives?

The Uncertainty Principle mainly applies to the behavior of particles at the microscopic level. Therefore, in our daily lives, we do not experience the effects of the Uncertainty Principle directly. However, it has had a significant impact on technology, as it has led to the development of devices such as transistors and lasers, which are essential components in modern electronics.

Is the Uncertainty Principle a proven theory?

Yes, the Uncertainty Principle has been proven through numerous experiments and is considered a fundamental principle of quantum mechanics. However, it is important to note that it is a probabilistic principle, meaning that it describes the behavior of particles in terms of probabilities rather than definite outcomes.

How does the Uncertainty Principle relate to other principles and theories in physics?

The Uncertainty Principle is closely related to other principles and theories in physics, such as the wave-particle duality, which states that particles can exhibit both wave and particle-like behavior. It is also connected to the concept of complementarity, which suggests that some physical properties cannot be observed simultaneously. Additionally, the Uncertainty Principle has led to the development of other theories, such as the Copenhagen interpretation, which seeks to explain the fundamental nature of reality at the quantum level.

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