Let's try and get 1,000,000 replies to this post

Magnus said:
Could you please tell your colleague to tell Andrew to tell Mr. Purkis that I thank him from the bottom of my heart for the excerpts from the rehearsal tape? Thanks a lot. (To you, not Mr. Purkis.)
Click to expand...

According to the 6 degrees or separation theory there are 4 people or less between you and anyone in the planet. This is based on the hypothesis that each one of the chain knows 100 the other doesn't.

Thus in the second link (first person except you) there are already 100x100= 10,000 and 5th link (4 people except you) 100x100x100x100x100 10,000,000,000 already above planet population. Add to that one more link to compensate any common acquittances between the links and you have a whopping 1,000,000,000,000.

And that's just 4 people between you and anyone else on the planet.

6 deg.png
 
Saapanael said:
Can anybody who knows physics (@Dr. Eddies Wingman) explain to me why the Doppler effect in acoustics does not depend on distance between the travelling and observing body? Let's say a police car with sirens is driving toward you at a certain speed and you're standing still. The formula of the siren's sound frequency change only takes into account the speed of the traveller, the original sound frequency of the siren and the speed of sound in the environment. But if the soundwaves the siren produces become more and more pushed together as the distance between you and the car decreases, shouldn't the frequency increase as the wavelength shortens?
Click to expand...
I can come up with an explanation, but I'll need a bit more than five minutes so I'll have to do it tonight :) But a short hint to get your thinking started: It's not a constant number of wave peaks between you and the moving object.
 
Saapanael said:
Can anybody who knows physics (@Dr. Eddies Wingman) explain to me why the Doppler effect in acoustics does not depend on distance between the travelling and observing body? Let's say a police car with sirens is driving toward you at a certain speed and you're standing still. The formula of the siren's sound frequency change only takes into account the speed of the traveller, the original sound frequency of the siren and the speed of sound in the environment. But if the soundwaves the siren produces become more and more pushed together as the distance between you and the car decreases, shouldn't the frequency increase as the wavelength shortens?
Click to expand...
If we want to understand this, we need to remember what the doppler effect is, in the acoustic (non-relativistic) world. Or what sound is, actually. It is an object that vibrates and creates pressure waves in its surroundings (in the air, for example). For you as an observer, what you hear as sound is each wave hitting your ear. The frequency (or pitch) is the inverse of the time between each wave.

So, what is happening when the source of sound is moving towards you? Yes, each wave sent towards you has a slightly shorter way to travel than the one before it, but it travels at the same speed. This means the time between two waves reaching your ear becomes shorter.

However, the soundwave itself really isn't fixed in space, so it's not compressed more and more when the sound source approaches a certain point (like your ear).

It's easier (although of course not mathematically strictly correct) to think of each wave peak as a separate wave travelling through the air. A moving source will be "chasing" the wave that goes in the forward direction while it "runs away" from the wave that goes the other way. So when it keeps sending out new waves, they will be closer together in the direction of travel, and further away from each other in the other direction.

And of course, when the source moves through the air at supersonic speeds, the whole explanation goes in the garbage :bigsmile:
 
Dr. Eddies Wingman said:
If we want to understand this, we need to remember what the doppler effect is, in the acoustic (non-relativistic) world. Or what sound is, actually. It is an object that vibrates and creates pressure waves in its surroundings (in the air, for example). For you as an observer, what you hear as sound is each wave hitting your ear. The frequency (or pitch) is the inverse of the time between each wave.

So, what is happening when the source of sound is moving towards you? Yes, each wave sent towards you has a slightly shorter way to travel than the one before it, but it travels at the same speed. This means the time between two waves reaching your ear becomes shorter.

However, the soundwave itself really isn't fixed in space, so it's not compressed more and more when the sound source approaches a certain point (like your ear).

It's easier (although of course not mathematically strictly correct) to think of each wave peak as a separate wave travelling through the air. A moving source will be "chasing" the wave that goes in the forward direction while it "runs away" from the wave that goes the other way. So when it keeps sending out new waves, they will be closer together in the direction of travel, and further away from each other in the other direction.

And of course, when the source moves through the air at supersonic speeds, the whole explanation goes in the garbage :bigsmile:
Click to expand...
That's what I thought. The soundwaves are not fixed to you as the observer, they move onwards in space so they don't stack up between the two objects. I have an exam in acoustics tomorrow and what misled me when going through the teacher's notes was a sentence about the frequency getting higher and higher as the car approaches the standing person. It's a mistake then.
 
Black Abyss Babe said:
Now, what rehearsal tape would this be? Will Thunderstick understand what I mean by "Magnus from Maidenfans said ..." or is this something you're, er, not really supposed to have?

It's not the one of Bruce on the bog is it?!!? :blink:
Click to expand...
Some time ago he had uploaded short excerpts (30 seconds to a minute) from a rehearsal tape featuring himself, Tony Moore, Terry Wapram, Dennis Willcock and a bass player whose name I'm forgetting right now, Steve or something. I think he could have easily made the whole thing public, as long as not making any money from it, but he chose not to, having met Maiden's lawyers before (story is well known I think). Nevertheless, even those short excerpts provided a unique insight into an early epoch of Iron Maiden, and I never thought I'd live to hear anything from it, hence my gratitude.
Some people have the entire thing, together with several bootlegs from the Dennis Willcock era, and at least one with Paul Mario Day, but I'm not among them, alas.
 
Last edited:
Saapanael said:
the frequency getting higher and higher as the car approaches the standing person.
Click to expand...
Could happen, but only if the car was accellerating, or being in a turn so that it came more and more straight towards the person (i.e. the speed component towards the observer increasing).

If the car approaches at a steady speed along a straight line and passes at "zero" distance, the observer will hear a constant freqency before the car passes and another, lower frequency after.

Good luck with the exam @Saapanael :)
 
Magnus said:
Some time ago he had uploaded short excerpts (30 seconds to a minute) from a rehearsal tape featuring himself, Tony Moore, Terry Wapram, Dennis Willcock and a bass player whose name I'm forgetting right now, Steve or something. I think he could have easily made the whole thing public, as long as not making any money from it, but he chose not to, having met Maiden's lawyers before (story is well known I think). Nevertheless, even those short excerpts provided a unique insight into an early epoch of Iron Maiden, and I never thought I'd live to hear anything from it, hence my gratitude.
Some people have the entire thing, together with several bootlegs from the Dennis Willcock era, and at least one with Paul Mario Day, but I'm not among them, alas.
Click to expand...
Ah I see, so it's a Maiden rehearsal tape, not a Samson one. Interesting!

And cool B)
 
You must log in or register to reply here.
Back
Top