Reflection and the measurement, and time irreversibility

In summary, reflection is a time-reversible process similar to using lenses, and it is not considered a measurement that can erase the coherence or interference pattern. When attempting to detect the path of a photon by measuring the momentum of a mirror, the uncertainty in the mirror's position will be great enough to destroy the interference pattern. This is because the mirror, when hit by a photon, will begin to rotate slowly and its position will become uncertain over time. Therefore, measuring the mirror's position at a later time will likely result in a different interference pattern being observed.
  • #1
Dmitry67
2,567
1
Reflection is not considered to be a measurement. Reflection, like using lenses is considered to be a time-reversible process. It is not a measurement and it does not erase the coherence (interference pattern)

Here is what I don't understand

What happens to the momentum of the photon? The light pressure? If I put a mirror (flying in a zero gravity and vacuum) right behind 2 slits, mirror will start rotating very slowly in a different directions depending on the path of the photon

Where is a flaw?
 
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  • #2
If you can measure the mirror's momentum well enough to detect which slit the photon went through, the posistion will be uncertain enough to destroy the interference pattern.
 
  • #3
My mirror is flying in the empty space. If it is hit by 1 photon, it begins to rotate making 1 full rotation per 1 year. So I make an experiment and decide to check the position of a mirror 3 month later. What is going to happen to the interference pattern?
 

Related to Reflection and the measurement, and time irreversibility

1. What is reflection and how is it measured?

Reflection is the phenomenon where light bounces off a surface and is redirected in a different direction. It can be measured by using a device called a spectrophotometer, which measures the intensity of light reflected off a surface at different wavelengths.

2. How does reflection contribute to time irreversibility?

Reflection plays a role in time irreversibility because it is a process that is irreversible. Once light reflects off a surface, it cannot be reversed and go back to its original direction. This means that the direction of light is affected by time and cannot be reversed, contributing to the concept of time irreversibility.

3. Can reflection be used to determine the age of an object?

No, reflection cannot be used to determine the age of an object. While the intensity of reflected light may change over time due to factors like weathering, it cannot be used as a reliable measure of age. Other methods, such as radiometric dating, are used to determine the age of objects.

4. What are some real-life applications of reflection and time irreversibility?

Reflection and time irreversibility have numerous real-life applications, such as in optical systems like mirrors and lenses. They are also important in fields like astronomy, where the reflection of light off celestial objects provides valuable information about their composition and movement. In addition, understanding time irreversibility is crucial in fields like thermodynamics and chemical kinetics.

5. How does reflection affect our perception of the world?

Reflection plays a crucial role in our perception of the world. It allows us to see objects, as light reflected off them enters our eyes and is processed by our brains. Reflection also affects the colors we see, as objects reflect certain wavelengths of light and absorb others. Additionally, our perception of time is influenced by reflection, as light takes time to travel and reflect off objects before reaching our eyes.

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