At the speed of sound

Anyone can post and discuss breaking science news or science-related public policy, that interests them (please respect posting guidelines and be sure to reference properly).
Forum rules
Please be sure to check our forum's Rules & Guidelines

At the speed of sound

Postby vivian maxine on June 7th, 2016, 7:11 am 

https://www.sciencedaily.com/releases/2 ... ce+News%29

We hear so much about how we cannot see the oldest stars and galaxies until their light reaches us. How about hearing the much slower sound at its speed?

A research team from University of Birmingham School of Physics and Astronomy has reported the detection of resonant acoustic oscillation of stars in M4, some of the oldest known clusters of stars in our galaxy, some 13 billions years old.
vivian maxine
Resident Member
 
Posts: 2823
Joined: 01 Aug 2014


Re: At the speed of sound

Postby Faradave on June 7th, 2016, 10:05 am 

"the team has studied the resonant oscillations of stars ... lead to minuscule changes or pulses in brightness, and are caused by sound trapped inside the stars"

The signal they're detecting is light (which comes to us at speed limit c) modulated by acoustic vibrations. Changes in that light intensity happen to be in the audible range. This is similar to an AM radio. The receiver in your home senses passing radio waves, which travel at speed c, but the amplitude modulation (AM) of that signal is controlled by the music (or other sound) source.
User avatar
Faradave
Active Member
 
Posts: 1834
Joined: 10 Oct 2012
Location: Times Square (T2)


Re: At the speed of sound

Postby vivian maxine on June 7th, 2016, 11:14 am 

Faradave » June 7th, 2016, 9:05 am wrote:"the team has studied the resonant oscillations of stars ... lead to minuscule changes or pulses in brightness, and are caused by sound trapped inside the stars"

The signal they're detecting is light (which comes to us at speed limit c) modulated by acoustic vibrations. Changes in that light intensity happen to be in the audible range. This is similar to an AM radio. The receiver in your home senses passing radio waves, which travel at speed c, but the amplitude modulation (AM) of that signal is controlled by the music (or other sound) source.


I did realize that later. It isn't the same as sound between two local points. It still puzzles me, how sound and light can be coordinated. It is hard to explain. I only know that eventually what they pick up by telescope will have to coordinate with what they pick up by radio, even if radio waves are light. Remember the early movies where you didn't watch the speakers'/singers' mouths if you wanted to listen to what they were saying/singing. Come to think of it, is there sound in outer space?

It's inspiring anyway. Another achievement.
vivian maxine
Resident Member
 
Posts: 2823
Joined: 01 Aug 2014


Re:

Postby Faradave on June 7th, 2016, 5:19 pm 

Image
User avatar
Faradave
Active Member
 
Posts: 1834
Joined: 10 Oct 2012
Location: Times Square (T2)


Re: At the speed of sound

Postby Dave_Oblad on June 7th, 2016, 7:09 pm 

Hi Viv,

We already have the technology to aim an invisible infrared laser beam at your home window glass and then read the bounced light via a telescope and amplifier to hear the conversation inside your house from blocks away. The sound vibrations of the glass modulates the laser light and the modulation can be amplified back into the sound from inside your home. The carrier medium is modulated light.

Police use a similar technology with a Radar Gun to measure the speed of a vehicle by detecting the Red or Blue Doppler shift of the radio waves beamed at your car and bounced back to the guns detector.

In space, I may not be able to hear you scream because there is no air.. but I could hear you talk if I detected light bounced off your spacesuit helmet and amplified the modulated reflected light back into local sound inside my helmet.

Hope this helped..

Regards,
Dave :^)
User avatar
Dave_Oblad
Resident Member
 
Posts: 3228
Joined: 08 Sep 2010
Location: Tucson, Arizona
Blog: View Blog (2)


Re: At the speed of sound

Postby vivian maxine on June 8th, 2016, 8:34 am 

You all have opened up a whole new puzzle for me. Wow! Just one question for now. A sound wave is not a sound wave in space; it's a light wave. Yes? So, is a sound wave a sound wave on Earth? When the fire engine deafens me, is it using simple sound waves or light waves? Or, better: When lightning strikes and thunder comes five seconds later (from five miles away), did it reach me by a sound wave or a light wave? At the point of strike, the sound and light were simultaneous. But sound travels more slowly - how?

I do hope that makes sense.
vivian maxine
Resident Member
 
Posts: 2823
Joined: 01 Aug 2014


Re: At the speed of sound

Postby Dave_Oblad on June 8th, 2016, 6:35 pm 

Hi Viv,

Sound is a compression wave of the air, such as thunder or voice. Radio is a compression wave of the electromagnetic field. Light is pretty much the same as Radio but a much higher frequency and shorter wave-length.

If I had a transmitter set at 1 million cycles per second or 1 MHz (one mega-hertz) and this frequency was maintained by application of a control voltage (say 1 volt) then if I modulated this control voltage up and down a bit.. the frequency I'm sending will increase and decrease a little bit to track my control voltage. Now if I give you a microphone and ask you to talk into it, it will produce a modulated voltage. If I apply that voice modulated voltage to the control voltage of my transmitter, the primary 1 MHz frequency will increase/decrease (modulate) based on that applied voice voltage from the microphone.

Now imagine the receiver is tuned to track the same frequency at 1 MHz using a voltage control. It is slightly different in that it will track the signal. It compares the received radio frequency of 1 MHz against an internal reference 1 MHz and if there is an error.. it will adjust the reference frequency using a controlled voltage to keep them tuned together (received and reference).

If I then take the receiver controlling voltage being used to keep the receiver tracking the frequency modulation of the transmitter, amplify it, and put that amplified voltage to a loud speaker, I get a reproduction of what ever sound is going into the transmitter's microphone (your voice).

That's FM Radio:
Voice > Microphone > Modulated Voltage > Modulated Transmitter Frequency > Received Frequency > Error corrected by Tracking Voltage > Speaker > Voice.

Voice through air travels at about 760 Miles per Hour. Radio/Light is about 186,000 Miles per Second. This is why you see the lightning sooner than hear it. The sound of an explosion will take a whole hour to be heard just 760 miles away. A radio/light signal could go all the way around the world 7 times in about one Second.

Hope this helps..

Feel free to ask any questions if I lost you.

Regards,
Dave :^)
User avatar
Dave_Oblad
Resident Member
 
Posts: 3228
Joined: 08 Sep 2010
Location: Tucson, Arizona
Blog: View Blog (2)


Re: At the speed of sound

Postby vivian maxine on June 9th, 2016, 7:28 am 

Thank you,Dave. I follow you fine. - I think. I am thinking that, with radio, we don't worry about air carrying sound. We use the scale of light waves and their vibrations. What I see - or think I see - is that we have developed the technology to bring sound to Earth by coordinating it with light. It isn't that I don't understand it in the explanations. It's that I can't imagine it - bringing in light waves and transposing them to sound by moving up and down the light wave scale. It is "magic".

I probably muddled that good. Let's just say I can accept that it is happening because everyone in the know says it happens. So, is that how an astronaut and the people in Houston talk to each other? Are their voices traveling at the speed of light?
vivian maxine
Resident Member
 
Posts: 2823
Joined: 01 Aug 2014


Re: At the speed of sound

Postby Dave_Oblad on June 9th, 2016, 4:42 pm 

Hi Viv,

Viv wrote:So, is that how an astronaut and the people in Houston talk to each other? Are their voices traveling at the speed of light?

Depends if they are in the same room or not. (lol)

Otherwise, via Radio, Yes.. Speed of Light.

BTW, Stars make all kinds of broad spectrum noise in the Electromagnetic Bands. You only need a Tuner to choose a specific band, point the antenna at the Sun/Star and listen to the information.. pops, clicks and hisses.. etc. When you mix all these signals together, you get static noise, like when you tune between stations on a Radio. That's the electromagnetic sound of the Universe.

Best wishes,
Dave :^)
User avatar
Dave_Oblad
Resident Member
 
Posts: 3228
Joined: 08 Sep 2010
Location: Tucson, Arizona
Blog: View Blog (2)


Re: At the speed of sound

Postby vivian maxine on June 9th, 2016, 4:50 pm 

Dave_Oblad » June 9th, 2016, 3:42 pm wrote:Hi Viv,

Viv wrote:So, is that how an astronaut and the people in Houston talk to each other? Are their voices traveling at the speed of light?

Depends if they are in the same room or not. (lol)

Otherwise, via Radio, Yes.. Speed of Light.

BTW, Stars make all kinds of broad spectrum noise in the Electromagnetic Bands. You only need a Tuner to choose a specific band, point the antenna at the Sun/Star and listen to the information.. pops, clicks and hisses.. etc. When you mix all these signals together, you get static noise, like when you tune between stations on a Radio. That's the electromagnetic sound of the Universe.

Best wishes,
Dave :^)


Do you suppose I got any of that when I had a radio with short wave? I did get Mexico. Even understood a bit of it. All the static and squawing came on the police band.

By the way, do you suppose all the speed-talkers we hear today are trying for the speed of light? I even suspect some may be close to making it.

Thanks much. More serious thinking tomorrow.
vivian maxine
Resident Member
 
Posts: 2823
Joined: 01 Aug 2014



Return to Science News Discussion Forum

Who is online

Users browsing this forum: Google Adsense [Bot] and 11 guests