A very good video on quantum mechanics

In summary, the video discusses the concept of quantized space and time, which means that both space and time are made up of discrete units rather than being continuous. This is a theory that is still being debated in the scientific community. The video also mentions how this concept ties into the idea of wave-particle duality in quantum mechanics. It also touches on the concept of energy levels and how they are determined by the structure of an atom or other system. The video references some other resources for learning more about quantum mechanics, including books and experiments.
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  • #2
In the fourth video of that series, he says space and time are quantized. I thought that wasn't fully accepted yet? Am I wrong or if not, where is evidence that Planck time and distance are really the shortest?
 
  • #3
Have a look at the latest B. Greene video (Quantum Leap) in NOVA it is good as well.
 
  • #4
why the wavelength would be perfect multiple, as described in this video?
 
  • #5
In the fourth video of that series, he says space and time are quantized. I thought that wasn't fully accepted yet?

correct.
You can check out "causal dynamic triangulation" as one example of a quantized view of spacetime. That's also been discussed in these forums.

In a recent discussion in these forums, a paper was referenced that presented the idea that "discrete" and "continuuous" spacetime are the same...there is no real distinction!
You can think of this concept in terms of an appropriate digital sample being able to fully replicate an analog information signal. Or even wave particle duality.
 
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  • #6
why the wavelength would be perfect multiple, as described in this video?

Think of a violin string as an analogy: the ends are constrained, so it can have only certain tones...certain vibrational patterns and associated energies. it's energy levels are constained to certain values...it's degrees of freedom are limited.

Another helpful analogy is to think of the electron as a wave...when it's in free space the wave is everywhere, it extends all over the place. But when attracted by a proton in a nucleus, for example, that wave is now localized...it's constrained and so its different from the free space case. And the constraint is also modified by the presence of other electrons and additional protons. Since the energy is contained in the wave, changing it's configuration via the presence of nearby particles changes the wave characteristic and likely energy levels. It's very unlikely for the electron to be found between allowed energy levels.

In contrast, a free electron can take on any energy level. But when it is part of an atom or a larger structure, it's constrained...it's degrees of freedom are determined and limited by the whole structure. So an electron's energy levels and degrees of freedom are determined by the numbers of protons in the nucleus as as well as the particular structure of a lattice, as examples. The Schrodinger wave equation describes these.
 
  • #7
Sarik Sadman said:
why the wavelength would be perfect multiple, as described in this video?

It has to be a perfect multiple to solve the "Ultraviolet Catastrophy" or blackbody radiation problem. See https://www.physicsforums.com/blog.php?b=584 [Broken]

This problem was solved when Max Planck proposed that that energy came in discrete packets or quanta and is the the basis of Planck units. Although it is not fully accepted that space and time is quantized an alternative solution that solves the black body problem has not been produced. Quantizizing space causes a number of its own problems, but it can be shown that if time is quantized and the speed of light is a constant, that the black body problem (and a few other problems) can be solved by only requiring that time is quantizing. There is no need to quantize space.
 
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  • #8
CK-12 Physics FlexBook has embedded videos on Quantum Mechanics which are simple and interactive. Moreover you will get theoretical detail to enhance the understanding of this concept.


Thanks
 
  • #9
Forestman said:
I don't think this is very good. The best way to learn quantum theory, imo, is to access the early papers on it. That is, learn something of the history of its development. Then get an early textbook, say, Bohm's 1950 "Quantum Theory", then access later textbooks and papers on it. Then, provided one understands all of the math presented, one should have a good grounding in the fundamentals of the quantum theory.
 
  • #11
Guys,

This video is really telling us that equilateral triangles that the national institute of standards has produced is the foundation of all mathematics, chemistry, and physics. We ought to study the index of retractions of this plastic equilateral triangle prism and understand that the line spectra is merely from sunlight bending and separating as a result of this plastic prism. However, if we use another material...perhaps we can learn more about atoms and particles... Who knows? Perhaps we can actually understand position and momentum of electrons at the same time!
 
  • #12
I like quantum mechanics
 
  • #13
Naty1 said:
correct.
You can check out "causal dynamic triangulation" as one example of a quantized view of spacetime. That's also been discussed in these forums.

In a recent discussion in these forums, a paper was referenced that presented the idea that "discrete" and "continuuous" spacetime are the same...there is no real distinction!
You can think of this concept in terms of an appropriate digital sample being able to fully replicate an analog information signal. Or even wave particle duality.

What was this paper? Sounds very interesting
 
  • #15
It is funny to think that everything in physics is theorized. However, I simply have to say that this was a good video. I don't have enough physics knowledge to make references, just ideas. Funny how they showed a string at the end. If the universe is digital right now, does that make strings analog?
 
  • #16
Okay, quantum physics is very new to me. I'm trying to grasp what's going on here. In the video, the speaker states, "The allowed orbits had to be exact multiples of the wavelengths calculated for the electrons. Other orbits produce destructive interference of the waves, and soon the electrons couldn't exist there."

I understand what's being said, but I don't understand why. What exactly is meant by 'destructive interference,' and why does it occur when the orbit of the electron isn't an exact multiple of the wavelength?
 
  • #17

1. What is quantum mechanics?

Quantum mechanics is a branch of physics that studies the behavior of particles at the subatomic level. It provides a mathematical framework to describe the behavior of particles such as atoms and molecules.

2. Why is quantum mechanics important?

Quantum mechanics is important because it helps us understand the behavior of particles at the smallest scale and has led to many technological advancements, such as transistors, lasers, and computer memory. It also plays a crucial role in many scientific fields, including chemistry, material science, and nanotechnology.

3. How does quantum mechanics differ from classical mechanics?

Quantum mechanics differs from classical mechanics in that it describes the behavior of particles on a microscopic level, while classical mechanics describes the behavior of larger objects. In classical mechanics, particles have definite positions and velocities, whereas in quantum mechanics, particles exist as probabilities and can exist in multiple states simultaneously.

4. What are some real-world applications of quantum mechanics?

Some real-world applications of quantum mechanics include transistors in electronic devices, magnetic resonance imaging (MRI), and quantum cryptography for secure communication. It also has potential applications in quantum computing, quantum teleportation, and quantum sensing.

5. How can I learn more about quantum mechanics?

There are many resources available to learn about quantum mechanics, including textbooks, online courses, and videos. You can also attend seminars and conferences on the topic or join a research group at a university. It is a complex subject, so be prepared to invest time and effort into understanding it fully.

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