strange shower thought about frequency and octave

[kamalmanzukie]

thought this through today and thought it seemed counter intuitive: if we live in a band limited universe (0hz - speed of light in a vacuum), and all indications point to yes, we do, that means while there is a definite maximum 'note' or frequency, there is no lowest note. frequency is bounded in the upper range by speed of light in a vacuum, but the number of octaves between middle c and 0hz is infinite, because one could always go down another octave by adding more time to the cycle. 1000 years per cycle? .00000000000000000000000000001 hz?

i mean it makes sense after thinking about it but it threw my head for a loop earlier

[BertKoor]

Sorry to say, not meaning to rain on your shower parade, but there is no limit to frequencies. Speed of light is of unit meters per second while frequency is cycles per second. A cycle is not a meter. You can double the frequency indefinitely just as you can halve it.

[kamalmanzukie]

might a suitable analogy be signals across an oscilloscope that flash across the screen faster than the speed of light but don't break the speed limit because no information is transferred? or like, say shaking a lazer pointer across the horseshoe nebula from earth, the dot moves faster but not really?

from how i understand the speed of light, it is basically the nyquist rate of the universe, if you'll forgive the metaphor. i had a hunch about the speed of light basically being equivalent to a planck distance. i guess that would be wavelength, so i'm confused, but i had a hunch about this and found some scholarly paper expressing basically the same idea

i would find the link but its friday night and i gotta go get crunk. cheers!

[BertKoor]

You are wrong. Meter <> Cycle.
Speed of light is what... 400.000.000 meters in a second? M/s. Not Hertz like in MegaHertz GigaHertz TeraHertz PetaHertz. Look up how many zeroes there are in a PetaHertz.

[vegaron]

You are wrong. Meter <> Cycle.
Speed of light is what... 400.000.000 meters in a second? M/s. Not Hertz like in MegaHertz GigaHertz TeraHertz PetaHertz. Look up how many zeroes there are in a PetaHertz.

1. Sound needs a medium to travel through.
2. Travelling sound waves are directly translatable to moving particles - atoms or molecules.
3. If those particles have an upper limit of speed, than sound waves must have an upper frequency limit.

You can raise this limit by using a medium of higher density or particles with a lower mass. But in the end, the particles have an upper speed limit.

Just my thoughts - I'm not a physicist but what I am comes quite close to that, so I hope I didn't embarrass myself by writing BS.

[Hooj]

of course there's a frequency limit.... look up The Debye Frequency!

[rifftrax]

Sorry to say, not meaning to rain on your shower parade, but there is no limit to frequencies. Speed of light is of unit meters per second while frequency is cycles per second. A cycle is not a meter. You can double the frequency indefinitely just as you can halve it.

If you're going to be an armchair physicist, at least check your claims... http://physics.stackexchange.com/questi ... an-em-wave

i.e. planck distance

[MadBrain]

The upper limit to frequency is not the speed of light (that only sets how fast waves travel, not how fast they can alternate), but rather: for photons, the required energy is proportional to frequency... eventually you hit a frequency that would take more energy to emit than the sum of all matter and energy in the universe.

Likewise, you could say that the lowest frequency that could meaningfully exist is bound by time it takes to reach the heat death of the universe.

[Aleatoriac]

Planck length.

The solution to Zeno's Paradox is that reality is quantized.

[BertKoor]

Let's put this theory to the test: can you divide a frequency more often than multiply it before you're out of the "meaningful" range?

The longest wave length must ofcourse be shorter in time than the age of our universe. Otherwise "repetition" is not feasible. How much time has passed since the big bang? The answer to that, according to Wikipedia is about 13.8 billion years; scientific notation 1.38E+10. Since there are 86400 seconds in a day and 365.25 days in a year, the age of the universe is about 4.35E+17 seconds. Say you need ten cycles in order to deduce it's cycle time, you get a frequency of about 2.3E-17 Hz, in words: 230 FemtoHertz

The shortest waves in the electromagnetic spectrum, according to Wikipedia is gamma radiation which has a frequency of 300 ExaHertz which is 3.0E+20 Hz.

Where's the middle inbetween 2.3E-17 Hz and 3.0E+20 Hz? The logarithmic middle inbetween these is 83.1 Hz with a factor 3.6E+18 (which is about 62 octaves) in either direction.

Then we need to establish what the center is of the audible spectrum of 20-20.000 Hz. You can take 640 Hz as the center because you can go 5 octaves in either direction and then hit a lower bound of 20Hz and higher bound of 20.48 kHz respectively. This is a factor 8 (3 octaves) off from the astrophysical determined "middle" frequency of 83 Hz. So if you start at 640 Hz you will hit the ceiling of 300 ExaHertz 6 octaves earlier than the bottom of 230 FemtoHertz.

Is six octaves (a factor 64) a significant figure in this perspective? Maybe it is! Or maybe not... I'd say it's close enough in either direction.

[edit] Some further research shows the OMG Particle has an energy of 3.0E+20 eV which is equivalent to 7.25E+34 Hz, adding another 47 octaves to the highest practicle frequency. That shifts the middle frequency considerably upwards, far outside off the audible spectrum.

[vegaron]

Sorry to say, not meaning to rain on your shower parade, but there is no limit to frequencies.

I'm confused. Do you believe now, that there is a frequency limit for sound waves or not?

I apologize in advance, this maybe harsh, but you obviously have no idea about physics.

• How can you convert a wave length into time, when you a) don't know anything about the propagation speed and b) don't have a medium for sound waves to travel or don't even assume one?
• As far as I remember, there is a maximum for observable wavelengths and that would be directly bound to the size of the universe. You don't need several oscillations to measure a wavelength. You won't be able to determine a wavelength with infinite precision anyway.
• Your scientific notation you seem to find necessary to write down is also false as it lacks the unit. Which is something no one can ever forget who has even the slightest affection for physics.
• I'm sure that he shortest wavelength in the EM spectrum, Wiki is talking about, does not mean the shortest wavelength possible but the shortest observed.
• You consistently mix up EM and sound waves, which you simply can not do as both are completely different physical phenomena.

I understand that the question kamalmanzukie posted is really interesting, but it has no solution you can easily derive from methods and knowledge you learned or are still learning in school. That's why I just point out some of your errors and don't even remotely try to answer this myself, because I would just end up making a lot of wrong statements.

Again, I'm sorry if this may sound harsh to you. Don't take it as an offence against you. I just want to show you, that physics is not as easy as we think it is before we begin to study it.


Cheers!

[BertKoor]

I just want to show you, that physics is not as easy as we think it is before we begin to study it.

Well thank you. This is exactly what science is about: pose a hypothesis, let others look at it critically and build a new hypothesis based on new insights. Repeat until all flaws are gone.

I'm confused. Do you believe now, that there is a frequency limit for sound waves or not?

I think there is no theoretical limit to frequencies. But surely there are practical limits, and I see no harm in exploring where these limits are. If you narrow it down to sound waves, I'm not sure where those limits exactly are. That will probably depend on where you put the goal posts of the definition of 'sound'. But that is not what we're discussing. As far as I'm concerned this is plainly about frequencies, regardless of where and how they occur. Sure EM waves are very different from sound waves, but what they have in common is that their frequencies are measured in Hertz. We're just exploring where the limits are, and which one of the upper and lower limits is furthest away.

I entered this discussion because contrary to what kamalmanzukie (the OP) stated, I don't think there's a direct relationship with the speed of light. Maybe indirectly there is though, I'm not sure.

How can you convert a wave length into time

I have not done that. I did start my second paragraph with "The longest wave length." Here 'length' does not refer to a distance but to it's length in time. If you read the full sentence carefully, you should have understood that, or maybe I should have stated that more explicitly.

You don't need several oscillations to measure a wavelength.

I disagree with that. We're exploring frequencies here, and in order to measure that you need something to reoccur periodically.

Say I slapped you in the face, just once. With what frequency did that occur? You cannot define the frequency of me slapping you in the face, because it only occurred once. So the lowest measurable frequency in this universe has a periodicy (in other words: wave length in time) that is lower than the time it has existed.

I wrote "you need ten cycles in order to deduce it's cycle time" but if it really matters to you, make that one cycle and thus the lowest frequency is then a factor ten lower: not 230 FemtoHertz but 23 FemtoHertz. Is that a significant difference? Maybe...

Your scientific notation you seem to find necessary to write down is also false as it lacks the unit.

I just checked that whole post, and there's just one occurence where I omitted the unit. Mea culpa, it slipped through. Surely this is NOT something I structurally omit! The notation itself is not wrong, unless you require it's noted as 1.23 * 10^45 instead of simply 1.23E+45.

[kamalmanzukie]

i think for the sake of my observation i was mostly referring to the electromagnet spectrum, whether its propagating through air or some mysterious 'everywhere field' what i was really trying to get at, was that i read the other day that the emf spectrum has about 80 octaves, and i said hey wait a minute...

i kinda had this idea that if you're at fifty hz, you go down an octave or two and you're at zero, having never really thought about it. i know that's not a very smart thing to think but understandable since notes get closer together going down until they stop mattering. again i realize i'm talking about sound now but really that's okay. my main point was basically hey it kinda seems like frequency has more room to go down than up, because going up you do run in to a speed limit before you'd run out of room or time.

i know wavelength and frequency are not the same, but they are related, and they are always propagating through time and space. i would make further assumptions but i really just mostly understand helium make voices funny so from here on out i make no claim of being correct about anything:

okay, i know about the harmonic series and how it converges and 'literally' keeps producing overtones into infinity, and i know not really anyone questions the universal speed limit, so is that why people are always doing sinking an axe in the planck length?

i would mourn its passing. i'm totally on board for the universe to be quantized, bandlimited, even digital. i found a book on the internet that basically said 'yeah, speed of light is the nyquist, plank distance something something wavelength. iono, maybe bit depth? anyway i tried to find it to appease the 'don't make posts about it unless you know it' but i guess it washed away on the internet

it seems to me frequency and wavelength could always increase if the other one could always decrease, and theres always more time and room? okay that makes sense, i never quite clicked with that. maybe displaying our ignorance prominently really is the best bet for meeting against the scourge of confusion

[Winstontaneous]

i think for the sake of my observation i was mostly referring to the electromagnet spectrum, whether its propagating through air or some mysterious 'everywhere field' what i was really trying to get at, was that i read the other day that the emf spectrum has about 80 octaves, and i said hey wait a minute...

i kinda had this idea that if you're at fifty hz, you go down an octave or two and you're at zero, having never really thought about it. i know that's not a very smart thing to think but understandable since notes get closer together going down until they stop mattering. again i realize i'm talking about sound now but really that's okay. my main point was basically hey it kinda seems like frequency has more room to go down than up, because going up you do run in to a speed limit before you'd run out of room or time.

i know wavelength and frequency are not the same, but they are related, and they are always propagating through time and space. i would make further assumptions but i really just mostly understand helium make voices funny so from here on out i make no claim of being correct about anything:

okay, i know about the harmonic series and how it converges and 'literally' keeps producing overtones into infinity, and i know not really anyone questions the universal speed limit, so is that why people are always doing sinking an axe in the planck length?

i would mourn its passing. i'm totally on board for the universe to be quantized, bandlimited, even digital. i found a book on the internet that basically said 'yeah, speed of light is the nyquist, plank distance something something wavelength. iono, maybe bit depth? anyway i tried to find it to appease the 'don't make posts about it unless you know it' but i guess it washed away on the internet

it seems to me frequency and wavelength could always increase if the other one could always decrease, and theres always more time and room? okay that makes sense, i never quite clicked with that. maybe displaying our ignorance prominently really is the best bet for meeting against the scourge of confusion

Check out the "Time Scales of Music" chapter in Curtis Roads' MicroSound...It's the best exploration of "temporal phenomenonology" I've ever encountered, and then the rest of the book provides ways to explore through DSP. He does seem to agree that the Planck time unit can be considered "the sampling rate of the universe". You gotta stop somewhere, or maybe it's turtles all the way down.