# Does a bullet have a wavefront stuck in its nose in vacuum?

## Main Question or Discussion Point

(like the wavefront that is photographed when it travels through air)

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DrClaude
Mentor
What do you think this wavefront is made of?

Nothing, I am asking for proofs with photographs, I am not supporting a theory that it is there or it is not there. Also, if nothing is seen at a photograph then I do not support the theory that it is there nor the theory that it is not there, I just want to find out.

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Physics_UG
Gold Member
The wavefront is made of AIR. If there is no air there will be no wavefront. DrClaude's question was rhetorical.

Here's a bullet with a plasma wave, but clearly it emphasizes bullet wobble if that's what you meant...

Bystander
Homework Helper
Gold Member
What do you think this wavefront is made of?
This is a hint.
Nothing,
This is your acknowledgement that you understand the hint.

russ_watters
Mentor
Nothing, I am asking for proofs with photographs, I am not supporting a theory that it is there or it is not there. Also, if nothing is seen at a photograph then I do not support the theory that it is there nor the theory that it is not there, I just want to find out.
On this forum, we require our members to put thought into their own questions. It helps them learn. That's why those questions were asked of you.

The wavefront is made of AIR. If there is no air there will be no wavefront. DrClaude's question was rhetorical.
The proof is some photographs you've seen? Where are they.

mfb
Mentor
Photographs that show the wavefront exists, and is made out of air pressure differences (or plasma, if the bullet is fast enough).

Borg
Gold Member
The proof is some photographs you've seen? Where are they.
Comet 67P. Maximum velocity of 135,000 km/h No air, no wavefront.

mfb
Mentor
Comet 67P. Maximum velocity of 135,000 km/h No air, no wavefront.
You can even say it has a velocity of 299,000 km/s - in a frame moving with roughly 299,000 km/s relative to us.
No air, not even a meaningful single velocity value.

Borg
Gold Member
You can even say it has a velocity of 299,000 km/s - in a frame moving with roughly 299,000 km/s relative to us.
No air, not even a meaningful single velocity value.
I left out the shockwave as it travels through the solar wind also.

sophiecentaur
Gold Member
The proof is some photographs you've seen? Where are they.
Your follow up to your OP is not logical. If you accept that there is no air / atmosphere then how can there be a matter wave involved? What "proof" would you need that something you don't expect in a non-existent medium is not there? In any case, what sort of photograph would you expect to show it?
You could ask about an EM wave, perhaps and you would find one if your projectile is accelerating and if it is charged but not if its velocity is constant.

"The wavefront the bullet has at its nose, is sound that cannot travel faster than the bullet, that΄s why it's stuck there, therefore I should not expect an electromagnetic wavefront stuck at the nose of the bullet unless its speed is at least the speed of light". I should not expect it to be photographed, or to exist? When a ball moves with e.g. 1metre/sec, it leaves a void behind it that air comes and fills it, therefore I expect a high density layer of air in front of the ball that is always stuck in the front of the ball, except the sound wavefront. So, instead of assuming I am all-knowing like God and know what΄s going on, I asked you of photographs of bullets in air void. Of any faster objects (not sub-atomic particles etc), also welcome.

russ_watters
Mentor
The line of questioning/reasoning still makes little sense, but Borg posted a photo of a comet -- Did you see it? Does it meet your needs?

sophiecentaur
Gold Member
"The wavefront the bullet has at its nose, is sound that cannot travel faster than the bullet, that΄s why it's stuck there, therefore I should not expect an electromagnetic wavefront stuck at the nose of the bullet unless its speed is at least the speed of light". I should not expect it to be photographed, or to exist? When a ball moves with e.g. 1metre/sec, it leaves a void behind it that air comes and fills it, therefore I expect a high density layer of air in front of the ball that is always stuck in the front of the ball, except the sound wavefront. So, instead of assuming I am all-knowing like God and know what΄s going on, I asked you of photographs of bullets in air void. Of any faster objects (not sub-atomic particles etc), also welcome.
The title of this thread says "vacuum". Now you want shock waves in air. I googled "shock wave images' (a reasonable enough phrase) and was flooded with pictures of objects moving high speed through air. Have you tried anything similar?
I can sympathise with your desire to see visual images of a physical phenomenon but examples of phenomena that can be actually photographed are very limited. Science can't only advance on the principle that 'seeing believing'; we mostly have to rely on much more subtle evidence than photographs.

Yes, I definitely think it does. If this bullet is travelling on Earth its wavefront would be consisting of air molecules and possibly other molecules in the air, but if it is travelling through a vacuum, it is completely different. It may not have a wave front, unless under specific conditions, of which it could then possibly have an extremely miniscule wavefront of space-time itself. Although, this would be a space-time warp, which we do not know to be possible yet.

The air wave photographed is this one, which is formed because the speed of the bullet is greater than the speed of sound:
http://en.wikipedia.org/wiki/Shock_wave
And I guess the corresponding eather wave is this one: