# What is the minimum volume that can be attained from crushing a car?

I had to make it unnecessarily wordy to get to the character limit. Simple question: How small can you crush a car? Any shape, doesn't have to be a cube, could be a sphere, maybe even a tetrahedron.

Say I have a Toyota Camry. What is the minimum volume I can crush this into?

• Actually there are tons of potential physics concepts. Apart from the obvious mechanical forces involved, a potential answerer could also describe the resultant nuclear forces from the application of sufficient pressure to induce fusion. I was thinking along those lines, but I was hoping there'd be an answer that incorporates calculations as well, since I don't have the necessary background to do them. Commented Oct 30, 2016 at 3:01
• There is a scene in the old 1960s movie "Goldfinger" where a Lincoln Town Car (I think it was a Lincoln) is crushed in one of those car crushing machines at junkyards. I think the crushed size was about 24 inches on a side cube. HOWEVER, I remember reading that this was far from possible. Some experts at crushing cars said that no Lincoln Town Car can be crushed into that size without it being cut up into pieces first and there fore multiple cubes of the size shown in the movie. Some of you may remember that scene. Commented Oct 30, 2016 at 3:45
• I think I owe you a beer,......
– user108787
Commented Oct 30, 2016 at 4:08

Drop it on a neutron star.

Density of a neutron star is roughly the same as an atomic nucleus, $3 *10^{17} kg/m^3$. Assuming the car weights around 1.5Ton that's $5 *10^{-15} m^{3}$ so a sphere of radius $10^{-5} m$ or $10 um$

• Or a black hole, it shrinks to Planck sizes Commented Oct 30, 2016 at 3:15
• Could you please elaborate on the black hole thing? Thank you! Commented Oct 30, 2016 at 3:20
• @BobBee but not verifiably so - you know how difficult insurance companies can be ! Commented Oct 30, 2016 at 3:20
• Martin picked a neutron star rather than a black hole, because there is a chance of wreckage surviving, proving the car is a write off and a claim being paid by his insurance company. If he had chosen the right black hole, from far away, the car could still be seen in one piece for a long time, as if it was still ok, so the insurance company would not pay out as they would say, "Mr. Beckett, you cannot prove there is the slightest damage to your vehicle and your claim is denied". You see, it's really all about money, not physics.
– user108787
Commented Oct 30, 2016 at 4:20
• So this is the part where I have to look beyond the Standard Model and GR to see if my car can go any smaller? Commented Oct 30, 2016 at 4:59

If you could heat the car and melt all its parts, then mold that into a sphere, that's the minimum volume.

In crashes, that may not happen. But, a lot of mechanical energy is converted into heat, which basically melts the parts and moulds them somehow.

If we have to go to the minimum, I think that sphere made earlier is the lowest we can go.

• Nice, didn't think of heating it
– user108787
Commented Oct 30, 2016 at 2:38
• Though do note that volume occupied would only depend on density of the melt, not shape. It could be a sphere, or a cube, or even a hollow sphere as long as we aren't counting the volume of air inside Commented Oct 30, 2016 at 3:23

At what point do you stop calling it a crushed car, and start calling it something else? (For example - a bunch of neutrons). If you do want to stop referring it to a car a some point during its destruction, and if you are adamant about crushing it, then the answers by Nawaj and Martin Beckett should help you out.

If you don't want to ever stop calling it a car, then read on! Collide the Camry with a requisite amount of antimatter. The car will survive as a burst of gamma radiation. The total energy thus released would be roughly $10^{20}$ joules. $10^{34}$ photons is what would be left of the car.

But a photon is not something you could really prescribe a volume to. They don't "Occupy space" in the same manner normal matter (fermions) do. This answer tells you why. So we could just be done with it and say that your car now has $0$ volume.

• I hadn't thought of the antimatter solution! I'm not going to mark this as the answer, because I still want a non-zero rest mass (this is the best way I can say, "I still want it to be something!"), but this is technically the best way of minimising its volume. Commented Oct 30, 2016 at 8:50