Physicists send supersonic shock waves rippling through a lab Scientists have managed to create powerful supersonic shock waves – comparable to those generated in space – under laboratory conditions. Shock waves are important in the universe. They drive cosmic rays and spread supernova particles close to the speed of light, kickstarting several physical phenomena such as the Aurora …
M12 work typically involves using shock tubes, giving such flows for less << 1 sec.
This is intriguing given the very low densities of the gases and plasma involved. In the universe these phenomena cover huge volumes of space so being able to model them in more detail, (like how they grow, what can make them shrink etc) should improve our understanding quite a lot.
First thing I noticed was the splash image.
"Artist's impression of a shock wave"
really.
Speed of sound would vary with atmospheric density - so not even the same from sea level to randomly chosen mountain top.
In terms of relevance its equivalent to cubits per lunchbreak, or double decker buses per long weekend - although that can be a measure of frequency as well as velocity - which makes it more versatile as a standard.
So using it is an arbitrary term to help explain things to idiots....
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"Artist's impression of a shock wave"
I may need to see a psychologist but that impression looks like an enflamed sphincter to me.
What was the artist thinking?
I am still wrestling with sonic boom in space, shirley that means the source of the shock wave is moving faster than the wave front?
As near as I can work out, the density of air is about 2.4 x 10e19 atoms per cubic centimeter. For comparison, an example of density in space might be that of the solar wind, at perhaps 3-6 ions per cubic centimeter (compare to an estimated "average" density of the interstellar medium of 1 atom / cc). So solar wind, and indeed the interstellar medium, are substances --- just highly rarefied ones.
Talking about Mach numbers in a plasma makes as much sense as talking about temperature of a plasma (a measure of the kinetic energy of the atoms in a material).
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Well I'm not the one who downvoted you - but I will answer your question (Knowledge after all should be shared and downvoting someone instead of explaining why they're wrong is just crass).
The speed of sound varies not only due to the medium (air, nitrogen, helium, you get the idea) but also due to the pressure and density of that medium. Near the ground on Earth for example, air is more dense meaning sound travels more slowly, 5 miles up it is less dense meaning sound travels more quickly. (the sound wave needs less energy to 'move' the less dense medium meaning it can travel more quickly). Even the temperature of the medium changes the speed of sound as a cooler medium is more dense and a hotter medium is less dense.
Given this, in space (which is not a complete vacuum) the speed of sound can be many, many times faster than the speed of sound at any height within Earths atmosphere.
Strangely the opposite is true for the speed of sound in liquids and solids, the more dense the liquid or solid, the faster sound travels.
Thanks James for that,
I appreciated about the different densities, heat and mediums.... it didn't click the opposite would happen in such an extreme with a partial (or almost complete) vacuum.
Sitting back and thinking about it does make sense. I'm a budding scientist and dabble in everything I can find and also always aware of my ignorance and always keen to correct it and form a firm(er) understanding.
So pfhhht to the Thumbs down brigade.
i did that 10 years ago with my EM drive, now BAE Systems are rocking half the speed of light with skylon 8 and the eurofighter 2
https://www.youtube.com/watch?v=IeNJ4qOZsxg
still using the general basics of ring magnets, and compress them to increase the retracting force to get alot more power while using the same amounf of power
https://www.youtube.com/watch?v=W2IKoxt16Ro
turning them off/on like a maglev train for propulsion
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