I was having a discussion with a friend about ***supersonic flights***. 
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[![Concord][1]][1]
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It was then when he proposed an idea on an interesting experiment that can be done during a supersonic flight. 

***The experiment goes like this.***

You board a supersonic jet along with your friend. The flight is cruising at **Mach 1** above Amazon rainforests, or some other place with comparatively low air currents.

You have somehow got the permission to do the experiment which involves *getting out* of the plane. 

You both take all the safety measures and stand on both the ends of the airplane with ***yourself near the nose, your friend near the tail***. 

***Your friend yells out something at you***, but you can't hear it, because it's Mach 1.

You ask the pilot to slow down the plane, and the ***plane gradually decelerates***. 

What happens now?

***Your friend's sound catches up with you, and you hear the message!***

Now, ***you yell out something at your friend facing forward***,realising that if you had faced backwards, your message would get ultrasonic for your friend.

Now, ***you speed up the plane, and your fried catches up with the message.*** 

Now, ***something remarkable*** happens when you do this. 

***Your friend hears the message in reverse!!***

Now the most interesting part:

If you ***keep on accelerating and decelerating the plane*** about the speed of sound, you can make your message ***to be heard multiple times by your friend!!***

Isn't it wonderful? Hearing the *same message* again and again without any effort from your part! 

***It is weird, but is such an observation plausible?*** 


  [1]: https://i.sstatic.net/qJDt1.jpg