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Name: Rodrigo
Status: student
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Question:
I just read that a proton is more like a cloud of fundamental particles, that come in and out of existence (quarks). So my question is, if all the fundamental particles come in and out of existence, would that mean that although I am me, mentally and physically the same, my matter is changing particles all the time?


Replies:
Rodrigo,

You are correct. What we experience at our day-to-day level is an average effect of all the little particles within us. Everything very small (single particles, individual atoms) is always changing. The constant change within a proton is what makes it a proton. Without these constant changes, atoms would not work. Protons would fly apart and neutrons would just float around doing nothing.

A larger scale example of constant change is a steel block setting on a table. Every atom is vibrating. Electrons are flying around within the block in every direction. Still, the block isn't moving. Each piece of the block, each atom, is always moving always changing how it moves. The whole block is going nowhere.

Ken Mellendorf


Rodrigo -

Some of that particle-changing is definitely true. But maybe not as much as it sounds like to you. Quantum mechanics shows us a picture of things being a slippery mess at the smallest scale, but at large scales virtually always averaging out to the usual predictable classical behavior.

The key words are "scale" and "average". What is the average rate of change of particles large enough to matter to you body? Really really slow. Your body does not care if inside the nucleus is a squirming ghostly mess, so long as this nucleus keeps having the same number of positive charges 99.999999999% of the time after a day of watching it. Which it does. A proton hardly ever escapes from a nucleus, even though its quarks may be doing a crazy dance.

Also, the electrons around the nucleus "delocalize", making probability clouds instead of circular orbits, but often they stay right on the same atom for a fairly long time. The quantum-tunneling jumps which electrons occasionally do, from one molecule to another, are the most fundamental part of chemical reactions. The body is a chemical machine, evolved to live with chemical reactions, so it is accustomed to most of the actions that electrons do, even though explaining them is weird.

On the other hand, some of the small-percentage chaotic results might be part of our aging process (which kills us in the long run), and we just do not know all about it yet. You only get to be you for a finite time...

Another thing: to see particles coming in and out of existence usually requires looking for them in very very short time-spots, kind of like what you see when a strobe-light flashes once. Looking at one proton for a whole microsecond is too long. Averaging happens in a time that long, and then the proton proves to be present almost every time you look for it that way. Sorry I do not remember off-hand just how short the time has to be for a proton to seem temporarily absent or unpredictable. I am sure that Plank's constant and the Heisenberg uncertainty formulas are what you use to estimate that. The relevant uncertainty formula is: dE * dt < [Plank_constant] So, your dt < [Plank] / dE "dt" for "delta time", means the passage of time while you look.

It is the time duration of your looking, in seconds. "dE" for "delta-Energy", means the change of energy that can occur unpredictably. dE for this question would be the mass-energy of the proton. Physicsts say the mass of a proton is about 1 GeV (giga-electron-volt) but you need to convert that into Joules. And you would need look up the value of the Plank constant. Anyway, dt for uncertain existence of a proton is many orders of magnitude smaller than a microsecond.

Hope that helps.

Jim Swenson


Rodrigo,

A good analogy might be a crowded sporting event or concert hall. Even though individual people come and go throughout the event, if you look at the stadium is generally crowded throughout the event, and the crowd makes a lot of noise even as people come and go. Even though one person might leave, it does not make a significant impact the overall crowd and its behavior.

With your example, if you look at a single particle that is inside you, depending on how you measure it, can act in the strange ways you refer to. However, when you consider a whole bunch of particles together (e.g. "you"), those effects become insignificant. The 'bunch' of particles acts in a more -- I will say "intuitive" -- way. That is why you do not see objects "disappearing" -- and why you do not disappear either.

Hope this helps,

Burr Zimmerman



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