Temporal Dilemma

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How do you presume to judge the usefulness of QM without knowing anything about it? Hmm?

Simple - measure its kinetic energy. Then, knowing its rest mass, you can figure out its former velocity. There are other ways, too. This is the most obvious, though.

Heh - if you don't accept most of QM as valid, what theory do you think fits the facts better?
 
I did not say anything about quantum theory being incorrect. What I said was no one understands it, including myself. When are YOU going to fess-up?
 
What do you mean, "understand it"? I can use the equations and produce a result that agrees in fine detail with reality. So can thousands of others around the world. If that's not understanding it, I don't know what is.

Example: no-one can visualize 4-dimensional space, but anyone familiar with 3D math can use the equations which describe 4D and understand how they work. You can't visualize a lot of QM, but you can still understand it (well, maybe not *you*...)
 
Pfft. Visualization is overrated. For thousands of years, people could visualize the path of a rock/cannonball through the air. But they didn't understand the concept of trajectories, even though they were visualizing it. Look at some medieval/Renaissance diagrams of cannonball paths. Straight across, straight down. It took math to help people understand that projectiles follow a parabola. Math.
You don't need to visualize it to use the equ'ns to produce predictions/analyses of what happens.

A quantum is a 'wave packet', that is a particle-like collection of waves which can act sometimes as a wave (ie dispersion, interference) and sometimes as a particle (ie collisions), and which represents the smallest amount of energy which can exist by itself (ie is indivisible).

But explaining physics without math is like explaining Shakespeare without the letters E through V. Well nigh impossible. Math is the language of science, and you need it to truly understand the nature of our world.
 
Hey cool you are doing good so far. And now for the $64,000 question:

Since the the energy of an electromagnetic wave drops with frequency (Hertzs, cps), how low would the frequency have to fall before it reached the minimum energy level of Planks constant?

I really don't know the answer, I'm not pulling your leg, I really want to know. Now Planks constant is (with out looking it up) about 6.5 X10 -33 ergs or watts.....well at any rate there is minimum energy, a shortest time, a shortest length etc. but nowhere have I ever seen the longest possible frequency, Plank frequency. The frequency that corresponds to one quantum of energy.

Calculate this and show the rest of us that you really do know your stuff. Thanx in advance.
 
From what I know of physics (provided, that's some first and second year stuff, the rest self-taught), there is no lowest frequency for photons. The equation I found was E=hv where E is the energy of one photon at the given frequency (in Joules), h=6.626*10^-34 is Planck's constant, and v is the frequency of the light in s^-1 . So one photon (quantum of light) of frequency v=5.1*10^14 s^-1 (which I think is one of the sodium lines) would have energy E=hv=3.37*10^-19 Joules. For larger frequencies, the quantum of energy increases, thus explaining why short-wavelength EM radiation packs such a punch. There is (AFAIK) no absolute smallest energy, or frequency, for subatomic particles.

I do recall something about an absolute smallest length, but I have no idea how to calculate it (or if I remember correctly).

But you see how we need math to understand this stuff? Direct, inverse, exponential relations... these are the meat and potatoes of science.
 
Why do you assume that no one can visualize 4 dimensions. I think it is rather easy to do. 5 and 6 dimensions aren't too hard as well. 7 is were it gets hard. You need to understand the nature of dimensions.
 
OK Raz,

If I've got it right Planks constant is 6.626x10^-34 JOULES (watts?). So if there is an electromagnetic wave that cycles a 1 Hertz then the energy contained in one photon at this frequency is equal to the same 6.626x10^-34 Joules. (E=hv).

Now if the EM wave is cycling at 1\2 Hertz then the energy of its photon is only 1\2 of a quantum (ie. 1\2 h). But isn't any energy less than Planks Constant supposed to be impossibe? If it is less than 'h' then it is SUBQUANTAL. Does the EM wave disapear below 1 Hertz or transduce into something else?

Is the 'wave packet' you spoke of, an EM wave or is it a packet of subquantal 'probability waves'?
 
Shadow:

Planck's constant is the energy of one PHOTON or particle of electromagnetic energy. An electromagnetic wave of one hertz will have a wavelength of 3.00 x 10^8 meters. If Einstein is correct a 1\2 hertz EM wave cannot exist.
 
Planck's constant is given in J*s ; that is, Joule-seconds. Which are a unit of work, not energy, as I recall. (Or is it power? I can never remember those properly...) So h does not define a minimum energy; it's just a constant that pops up in a lot of equations, like G or c or K, etc. h is *not* the energy of a photon; it's not an energy at all.

One thing you should note is that a photon with v=1 Hz would, AFAIK, be undetectable to modern equipment. This would be far into the gamma-ray range, very, very weak (look how small the energy is).

The wave packet is, of course, an EM wave (being a photon and all...), but is also, according to the quantum model, a set of probabilities, inasmuch as everything is just a set of probabilities. Heisenburg's uncertainty principle.

kentheee, if you can really visualize 6 dimensions (not just mathematically), then I suggest you take yourself down to your local university psychology department and prove it to them. You'll fast become a celebrity, as no one in the history of humanity has ever been recorded as being able to visualize even 4 spatial dimensions. In the highly unlikely event that you can actually do this, you must be some kind of freakish super-mind.
 
Well, ain't this all clear as mud. If you want a different set of 'facts' talk to a different set of people.

Here, try this one on for size] Each and every photon has the exact same amount of energy (6.626*10^-34 JouleSECONDS) but the variable is the time over which it is delivered, aka wave length.

If this is so, then I've answered my own question. A 1\2 hertz wave (assuming an EM wave formes at so low a frequency) would consist of one quantum of energy delivered over 2 seconds.
 
*Warning... Grade 11 Physics primer below*

The Joule is a unit of energy. The only SI unit of energy. All energies given in SI units must be given in terms of joules.

The joule-second is a unit of work. It cannot be used to express an energy, as it is not the proper unit.

Wavelength is the distance between two peaks on a wave, and is measured in metres. It is not measured in seconds.

**

<sarcasm>
How convenient that you, who posed the question in the first place, miraculously gain the ability to answer it as well!
</sarcasm>
 
Picky picky. So each EM wave has one quantum of POWER when measured in units of 'h' reguardless of wave length or frequency (WHICH IS THE SAME BLESSED THING inversly related).

Mechanics do 'work'. Electricians do 'power'. Again, its the same thing, and if you better understood the math you use, you'd know that already.

But I still say, high frequency waves deliver the same amount of ENERGY in a lesser time giving more "energy per unit of time" which is technically speaking more POWER. Thank you.

Have a nice and be real carefull around things that give off sparks.
 
Razmatazz:
In 1900 Max Planck found a theoretical formula that exactly describes the intensity of LIGHT of various frequencies emitted by a hot solid at different temperatures. Earlier,
others had shown experimentally that the light of maximum intensity from a hot solid
varies in a definite way with temperature. A solid glows red at 750 degrees C, then white
as the temperature increases to 1200 degrees C. At the lower temperature ,chiefly red light is emitted. As the temperature increase, more yellow and blue light become mixed with the red, giving white light.
According to Planck, the atoms of the solid oscillate, or vibrate, with a definite frequency depending on the solid. But in order to reproduce the results of experiments on glowing solids, he found it necessary to accept a strange idea. An atom could have only certain energies of vibration, E, those allowed by the formula
E = nhf, n = 1,2,3,......, f = frequency
where h is a constant, now called Planck’s constant, a physical constant with the value
6.63 X 10^-34 j/s, ( j/s simply means ENERGY per unit of TIME. ) The value of n must
be 1 or 2 or some other whole number. Thus, the only energies a vibrating atom can have
are hf, 2hf,3hf, and so forth. The number symbolized by n are called QUANTUM numbers. The vibrational ENERGIES of the atoms are said to be quantized; that is, the possible ENERGIES are limited to certain values.
Planck himself was uneasy with the quantization assumption and tried unsuccessfully to eliminate it from his theory. Albert Einstein, on the other hand, boldly extended Planck’s work to include the structure of light itself. Einstein reasoned that if a vibrating atom changed ENERGY, say from 3hf to 2hf, it would decrease in energy by hf, and this ENERGY would be emitted as a bit ( or quantum ) of light ENERGY. He therefore postulated that light consists of quanta ( now called PHOTONS ), or particles of electromagnetic energy, with energy E proportional to the observed frequency of the light:
E = hf.. Hence, the minimum ENERGY of one photon is E=hf = (6.63x10^-34 j/s) x (1/s) = 6.63x10^-34 j of ENERGY!!
The frequency of GAMMA rays is about 10^20 hertz a lot more then 1 hertz. If you do
the math you would see that gamma photons are the highest ENERGY photons.
 
Shadow, you said:
"So each EM wave has one quantum of POWER when measured in units of 'h' reguardless of wave length or frequency."

Don't be silly. The equation's E=hv . The h has no physical reality, it's just a constant that happens to fit observation. Just because it accidentally has units of work means nothing; would you claim that the units of G (which are something like Newton-metres per square kilogram) have special physical significance in their own right? That's just silly.

Work and power and energy are three related, but seperate things. If you'd learned even grade 11 level physics you'd already know this.

The equation E=hv specifically says that photons of different frequencies DO NOT have the same energies. I thought that was pretty explicit in the equation; you do grasp the math, right?

Time~master, sorry about the gamma-ray thing. What I meant to say was that a 1 Hz photon would be well into the *radio* wave range. I just went the wrong direction on the spectrum. Oops. Nevertheless, the 'tiny energy' point still stands.

I think you need to be more careful with the math you use - the units of h are J*s , not J/s (BIG difference!). And your equations showing the 'minimum' energy of one photon are not general. You only derived the energy of a photon at 1 Hz, which is different from the energy of a photon at, say, 10^6 Hz (E=hv=6.63*10^-28 J). There's nothing I see in the theory to prevent a photon at 1/2 Hz, or 1/4 Hz, or whatever. Show that and I'll be impressed.

You did rather well at explaining why excited photons emit different wavelengths of light, though.
 
Looks to me like TimeMaster has mastered the math. Razmataz re-read his post, nice and slow this time. Is h j*s or j\s? Is there or is there not a MINIMUM energy for the photon? You seem to dive right for the details and blow right past the larger picture as if there were none.. Slow down Bud, and enjoy the view..
 
Ok I have a question, now if you were to some how go back in time would it be probaly only possible by transfer of matter. <Teleportation> Now if you could do this couldn't you just transfer the same mass from the pass to the futre and when you go bakc so dose the matter. So it would not add or subtract. Now if somehow time travel is possible couldn't teleportation?

I think I just made a cool respawnse.

P.S. Sory for spelling no spell check.
 
Um, Shadow, why don't you reread *my* post? I assure you that everything in there is true (except for one typo). Time~Master made some errors in his post, and some invalid assumptions. I simply corrected him. It doesn't seem as if you have even a Grade 11 acquaintance with physics, so who are you to judge who knows the math better? h IS in J*s (look it up in any physics text), and E=hv defines NO minimum energy for the photon; Time~Master's math only applies to a photon at 1 Hz. And I don't know what you mean by details vs. the big picture - I'm just dealing with the maths, which is what all this is about anyway.

The typo was in the last sentence - it should have read "<...> excited atoms emit <...>". Sorry.
 
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