Discussion in 'Physics' started by logicman112, Jan 6, 2011.

1. ### logicman112 Thread Starter Active Member

Dec 27, 2008
69
2
I want to talk about modern physic and wave function, the probability density and a particle trapped between walls. We obtain some energy levels, valid wavelengths and some valid forms of wave function which are sinusoidal.
Physics books only say that wave functions can be one of those sinusoidal with different wavelengths but can a wave function be a combination of some of those sinusoidal functions? Why a sum of those functions is never discussed in modern physics books?

The second question: Is a particle considered as a mathematical point in quantum physic? When we talk about the probability of presence of a particle (the wave function intensity), what does it really mean? Is that particle a mass which has a volume? The probability is fundamental or it is a number which the measurement gives us?

2. ### Kermit2 AAC Fanatic!

Feb 5, 2010
3,852
968
A wave function can be as complex or as simple as you want to make it.

The majority of them are merely probable, but not 'practical'.

The wave function for an electron will show it as occasionally being far outside the realm of it's atom's nucleus, or even within it. But if plotted millions of times, the different positions evolve into a 'cloud' of probability.

It is a mathematical TOOL to understand electron distribution, there is NOT any fact there supporting it is the true way things work. It just happens to describe it accurately

particles are considered as math 'points' for some calculations and as 'billiard balls' for other calculations.

distribution calculations are point based. crystal lattice Xray diffraction needs actual atomic structure sizes for calculations

3. ### logicman112 Thread Starter Active Member

Dec 27, 2008
69
2
Thank you, Kermit2.
But I have become really confused! When we talk about the probability of the presence of a particle, it means that there exists a particle with a specific mass and volume. But the game of wave function considers a particle as a mathematical point(you were right) without volume. How this mathematical tool believes in presence of a material particle(like what we see in our regular everyday experiments) but without volume?!!
It seems illogical.

4. ### Wendy Moderator

Mar 24, 2008
20,772
2,540
You aren't alone. There are a lot of basics that seem stable, but the fine print is being rewritten all the time.

The duality of the waveform and quantum particle does seem like a paradox (because it is in many ways), but it is the best we can do at the moment.