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Re: [Phys-l] Special Relativity



Think about how the sound information is encoded into the E&M wave that is sent. Will it be an FM signal; an AM signal; a digitally-sampled signal? Then think about how this will be decoded at the receiving end. Then ask yourself whether a red shift or blue shift of the E&M wave would affect this encoding/decoding process.

Today the message would be a string of digital numbers that represent the sound wave sampled at some rate and using a particular number of bits of resolution. Assuming the sender and receiver are using an agreed upon system (such as MP3 or AAC) using an agreed upon sampling rate, how could that affect the message?

If you download music from a source such as iTunes, depending on your bandwidth and competing traffic, you might receive a song in 15 seconds that has a playback duration of 3 minutes. One might say that the transmitted information was received extremely blue-shifted. Yet it sounds just fine when played back with the appropriate decoding method that is operating at the proper playback rate.

Michael D. Edmiston, Ph.D.
Professor of Chemistry and Physics
Chair, Division of Natural and Applied Sciences
Bluffton University
1 University Drive
Bluffton, OH 45817

419.358.3270 (office)
edmiston@bluffton.edu


--------------------------------------------------
From: "Robert Yeend" <ryeend@sbcglobal.net>
Sent: Tuesday, February 01, 2011 2:24 AM
To: "Forum for Physics Educators" <phys-l@carnot.physics.buffalo.edu>
Subject: [Phys-l] Special Relativity

Help, please!

A student asked the following question, to which I did not have a
ready answer:

"If someone on earth sent a message to a person in a spaceship
traveling at relativistic speed, would the voice on the message sound
distorted because of time dilation?"

Ideas?

Bob Yeend
Justin-Siena HS
Napa, CA
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