Heisenberg's Uncertainty Principle Explained

TL;DR

When narrowing a slit through which a green laser is fired, the spot on the screen behind it initially gets narrower, but then starts to spread out due to Heisenberg's Uncertainty Principle.

Transcript

Today I am doing an experiment that demonstrates Heisenberg’s Uncertainty Principle. Sao her I have a green laser and I am firing it down towards the front of the room through a narrow slit. Now that slit can be adjusted so it can be made narrower or wider. And the laser spot is projected on to a screen behind it. So what do you think is going to h... Read More

Key Insights

• 🙃 By narrowing a slit through which a laser is fired, the spot on the screen initially becomes narrower and the sides are cut off.
• 💻 The spreading of the spot on the screen as the slit is further narrowed can be explained by Heisenberg's Uncertainty Principle.
• 🧘 Heisenberg's Uncertainty Principle states that the uncertainty in position and momentum must always be greater than or equal to a certain value.
• 🧘 Narrowing the slit decreases the uncertainty in position, causing the uncertainty in momentum to increase.
• 😁 The uncertainty in momentum being spread out results in a wider beam on the screen.
• 🛟 Heisenberg's Uncertainty Principle is not noticeable in everyday life because objects are much larger than the scale at which it becomes significant.
• 🙂 The controversy surrounding the explanation of the experiment relates to whether light should be seen as a wave or particles.

Questions & Answers

Q: What happens to the spot on the screen as the slit is narrowed?

Initially, the spot on the screen becomes narrower and the sides get cut off. However, as the slit is further narrowed, the spot starts to spread out.

Q: How does Heisenberg's Uncertainty Principle explain this phenomenon?

Heisenberg's Uncertainty Principle states that the uncertainty in position and momentum of a particle must always be greater than or equal to a certain value. When the slit is narrowed, the uncertainty in position decreases, causing the uncertainty in momentum to increase and resulting in the spread of the spot on the screen.

Q: Why don't we experience Heisenberg's Uncertainty Principle in our everyday lives?

The uncertainty in position and momentum becomes significant only at very small scales, such as the size of particles. In our everyday lives, objects are much larger, so the uncertainty is negligible.

Q: What is the controversy surrounding this explanation of the experiment?

The explanation of the experiment is controversial in the context of whether light should be seen as a wave or particles. If light is seen as a wave, then the spreading of the beam can be explained by the phenomenon of diffraction, where waves bend at corners and radiate out. However, this raises questions about the true nature of light.

Summary & Key Takeaways

• By narrowing the slit through which a green laser is fired, the spot on the screen behind it initially becomes narrower and the sides are cut off.

• However, as the slit continues to be narrowed, the spot on the screen starts to spread out, contradicting expectations.

• This phenomenon can be explained by Heisenberg's Uncertainty Principle, which states that the uncertainty in position and momentum of a particle must always be greater than or equal to a certain value.