20
$\begingroup$

A small perfect sphere is suddenly gone. Everything inside is teleported somewhere -- through space or even maybe through time, we're not sure. It's a small sphere, just enough to fit a human sitting on a chair. The perfect vaporization affects everything -- most of the chair, large part of the desk, air. What's left behind is just vacuum. No flash, no explosion, no sound. (The fact that this can happen is the only part I can/want to handwave, but bonus points for a reality check here.)

But what happens to this space moments after it happens? What would a blob of empty space do when placed in the atmosphere -- precisely, in an office full of tech equipment. Would there be an explosion after all? Would it create an energy blast? Would it feel like a wind coming from it or going towards it? Could it do something to the laptops and phones nearby?

Improve this question
$\endgroup$
13
  • 12
    $\begingroup$ There is a kind of underwater crustacean that does exactly this: it retracts it's tail so fast that water can't keep up with this speed. It results in pressure explosion that kills nearby plankton creatures. $\endgroup$
    – Barafu Albino
    Sep 16, 2018 at 21:57
  • 1
    $\begingroup$ I edited the title so that "part of the world" would not imply "part of the Earth". If you disagree with it, feel free to revert the edit. $\endgroup$
    – RonJohn
    Sep 16, 2018 at 22:21
  • $\begingroup$ @BarafuAlbino yet there is a significant difference in density between water and air... $\endgroup$
    – Ister
    Sep 17, 2018 at 7:53
  • 2
    $\begingroup$ Here's a effect like this decribed $\endgroup$
    – user55267
    Sep 17, 2018 at 11:47
  • $\begingroup$ You can observe an artistic impression of this phenomenon at the conclusion of the Adama Maneuver (if I may say, an outstanding scene in my humble opinion) $\endgroup$
    – Tom W
    Sep 17, 2018 at 13:01

5 Answers 5

Reset to default
42
$\begingroup$

A very similar question was covered in What if series, applied to a glass.

Quoting from there:

We’ll imagine the vacuums appear at time $t=0$.

For the first handful of microseconds, nothing happens. On this timescale, even the air molecules are nearly stationary. For the most part, air molecules jiggle around at speeds of a few hundred meters per second. But at any given time, some happen to be moving faster than others. The fastest few are moving at over 1000 meters per second. These are the first to drift into the vacuum.

After a few hundred microseconds, the air rushing into the glass on the right fills the vacuum completely and rams into the surface of the water, sending a pressure wave through the liquid. The sides of the glass bulge slightly, but they contain the pressure and do not break. A shockwave reverberates through the water and back into the air, joining the turbulence already there.

In a few more milliseconds, it reaches the humans’ ears as a loud bang.

The bang will be pretty loud. I happened once to force open a vacuum chamber not yet fully vented, and though it was not in deep vacuum (just few millibar) it sounded like somebody had given a strong hit with a hammer.

Maybe the shockwave would be strong enough to shatter some fragile glass and damage some MEMS (like the microphones in the telephones).

Improve this answer
$\endgroup$
27
  • 5
    $\begingroup$ If you're vacuum chamber did the sound of a hammer something $5m^3$ big would probably shatter all the windows of the house and the vase of your mother-in-law $\endgroup$
    – Jean-Abdel
    Sep 16, 2018 at 17:36
  • 5
    $\begingroup$ Note - the answer to this question depends on what the OP means by "small". If it is 10cm there would be a POP. If a meter a big bang and shaking. If 10m there would surely be a hurricane-earthquake like effect. $\endgroup$
    – Fattie
    Sep 17, 2018 at 3:54
  • 2
    $\begingroup$ @Fattie, OP states "enough to fit a human sitting on a chair". That's about 80 $dm^3$, or 80 liters. $\endgroup$
    – L.Dutch ♦
    Sep 17, 2018 at 6:00
  • 9
    $\begingroup$ I'm not the asker, but I'd love a physicist to chime in about atoms splitting at the edges, too. If the volume removed has a mathematically precise edge, then aren't we inevitably splitting atoms, and even sub-atomic particles, to the extent that they can be considered to be in a specific place? $\endgroup$
    – whybird
    Sep 17, 2018 at 6:03
  • 6
    $\begingroup$ @Fattie If the removal follow a precisely defined edge, then we also have to consider the uncertainty principle. Though the volume of space being emptied might be precisely defined, the position of particles isn't. So every particle will randomly be removed or not removed, but for particles far from the edge the probability will be close to 0% or 100%. But is this going to work out in such a way that entire molecules end up on the same side with a certain probability distribution among the two sides, or will it split molecules and maybe even atoms? $\endgroup$
    – kasperd
    Sep 17, 2018 at 8:29
18
$\begingroup$

What would a blob of empty space do when placed in the atmosphere -- precisely, in an office full of tech equipment. Would there be an explosion after all? Would it create an energy blast? Would it feel like a wind coming from it or going towards it? Could it do something to the laptops and phones nearby?

The same thing that happens after a lightning strike heats up the air so much that the hot gasses expand, causing a partial vacuum where the lightning was: air rushes back in really fast because nature abhors a vacuum.

And we all know what goes with lightning: a really loud thunder clap that -- if close enough -- breaks glass and sets off car alarms when the rapidly in-rushing air bounces against other bits of in-rushing air and bounces back.

Improve this answer
$\endgroup$
12
  • 1
    $\begingroup$ Not clear how expanding gas would cause a vacuum. According to en.wikipedia.org/wiki/Thunder, a thunderclap is caused by the rapid expansion itself, not by a vacuum (unless you're going with the 19th-century theory). $\endgroup$
    – LarsH
    Sep 17, 2018 at 3:38
  • 3
    $\begingroup$ @LarsH it's the rebound after the rapid expansion. That very well might be the 19th century theory (I'm old enough to have been taught "New" Math instead of just Math...) but the Wikipedia article starts by saying "Thunder is the sound caused by clouds rubbing together" and that's more than a bit dubious... $\endgroup$
    – RonJohn
    Sep 17, 2018 at 5:41
  • 2
    $\begingroup$ For nature abhorring vacuum there is quite a lot of it around in space. The opposite appears to be rather true. ;) $\endgroup$
    – Battle
    Sep 17, 2018 at 5:50
  • 13
    $\begingroup$ I never liked the phrase ‘Nature abhors a vaccuum’. It’s objectively wrong. Nature loves vaccuum. It loves it so much that it’s doing its best to make sure all the matter is in dense lumps so it can enjoy untrammelled vaccuum for lightyears and lightyears. Even on a smaller scale: molecules love vaccuum, it briefly stops them being jostled by their neighbors!! </pointless rant> Good answer! $\endgroup$
    – Joe Bloggs
    Sep 17, 2018 at 5:53
  • 2
    $\begingroup$ @NicHartley: Nature loves human scale vacuums too much. $\endgroup$
    – Joe Bloggs
    Sep 17, 2018 at 18:46
5
$\begingroup$

This is somewhat similar to the situation in a "vacuum cannon" - one of those research/demonstration devices where they accelerate light objects like ping pong balls or meteorite models to very high speeds, way past mach 1, by

The problem is, there's always extra noise involved with those, like breaking the diaphragms and the thing they're firing hitting stuff.

My guess here is that it would be very noticeable but not very damaging=there would be a sudden wind towards the hole and a drop in pressure that would really thump your eardrums, but any kind of sonic wave from the air colliding in the middle of the hole would be almost nothing because its surrounded by a much bigger shell of rarified air, blowing directly towards it. Even if you were right at the boundary when it disappeared, I can't see it would be any different than a very very hard gust of wind.

I can't see how there could be any supersonic effects or any overpressures over 1 bar, outside a spherical void, because all the energy and air involved in the middle would have to reduce the pressure and total energy outside the void... which geometrically is going to be bigger (although that effect obviously goes away the bigger the void is, until at some huge size you could pretend the boundry was a flat plane i guess)

Now if the area that suddeny becomes vacuum had some interesting shapes, I think you could produce weird jet effects by changing the shape, but i still dont see how you can transfer much energy outside the area if the entire area disappears at one time. Those vacuum cannons work by breaking the membranes at different times.

TLDR: i think people right at the boundary would get blasted off their feet by wind or smashed by cars or buildings blowing onto them. They wouldn't have permanent hearing damage or even burst eardrums, but they'd all go OW what was that whomp noise. They would all get really cold really fast but very briefly, and there might be a wave of sudden white mist that went away in seconds.

people standing around 2 radiuses or more from the center of the void would probably just feel a strong gust of wind and hear a huge WHOMP noise, and 3 or 4 radiuses people would just hear a weird echoey whomp.

super short still TL still DR: I think it would be pretty underwhelming, there's a lot less kinetic energy involved than a small bomb or something, and less transmission of it.

Improve this answer
$\endgroup$
5
$\begingroup$

Mini sonic boom as the air rushes in to fill in the empty space. It's not really a huge volume of air but people within a meter (yard) would certainly feel both the suction as well as feel the concussion of the rebound, papers would be tossed around the room, books/binders may be pulled off of shelves. People within several meters would certainly feel the momentary pressure differential, calenders would wave as the air rushed past to fill in the space. People further away wouldn't feel much, if anything at all, but would certainly hear the bang which would sound like something like a large firecracker (but probably not as big as an M80).

A more interesting question would be: If this is the way your teleporter works, what happens at the place where the matter re-materializes?

Edit: Coincidentally I was just watching Predestination, which is a time travel movie, and I think they depict this very well. When the time traveler leaves one place everything in the room is sucked in the direction of where he was. At the place where he materializes everything is pushed back out of the way as if momentarily blown by a strong wind.

Just an added perspective.

Improve this answer
$\endgroup$
3
  • 2
    $\begingroup$ When I think about teleporters, I always want them to swap the content of two volumes rather than just removing one, to avoud as much matter-overlap at the receiving end as possible. BUT, to maintain causality, there still has to be at minimum a light-speed delay between the contents of one volume leaving and the other arriving (at both ends). Depending on the distance involved, this could easily be significant, and presumably there is a total vacuum in the meantime... and even if the delay is short, SOME atoms at the edges will have drifted in. $\endgroup$
    – whybird
    Sep 17, 2018 at 5:57
  • $\begingroup$ @whybird Thanks for chiming in -- the "distance" covered is zero because the movement happens through time planes. $\endgroup$
    – Lazar Ljubenović
    Sep 17, 2018 at 7:54
  • 3
    $\begingroup$ There is only spacetime. $\endgroup$
    – amI
    Sep 17, 2018 at 8:03
1
$\begingroup$

It's not directly answer to your question but it's based on one of comments:

the idea is that a sphere slips through time while duplicating itself -- like cell division, but through time (not space). This leads to whatever taking its place from another time plane (chances are that it's a chunk of outer space). One duplicate goes to whatever, while the other duplicate creates a new time-plane. I guess that I'll need to anchor the spheres from time-planes into same or similar Earth coordinates (something with gravity?) to avoid the sound and wind. It has to be mostly unnoticeable.

Make the sphere 4D with time as fourth dimension. This way the empty space won't be an immediate one but gradual which means the pressure just drops slightly and gradually while the 4D sphere moves out of the current time plane. You can set the timing as you please to avoid sudden rush of air and limit any other unsuitable effects.

Let's assume we have a standard open-space. In the building I currently work a single floor area is around $2100 m^2$. The height of a floor is aroung $3 m$ giving a volume of $6300 m^3$. A sitting person has height of roughly $1.4 m$ so a 3D sphere that is the intersection of 4D sphere and the current time plane has a volume of

$$ V_S = \frac{4}{3} \pi r^3 = \pi \cdot \frac{4}{3} \cdot (\frac{7}{10})^3 \approx 1.5 \space (m^3) $$

So it occupies as little as 0.24% of total space. If the original pressure was 1013 hPa (an average atmospheric pressure), with a gradual change after it completes the pressure will drop to 1012.76 hPa

For comparison, when flying on a typical airliner, the pressure drops in about 20 minutes (the ascending time) from the ground pressure (1013 hPa on average) to the pressure that exists on 7000 ft, which is approximately 782 hPa. It means the pressure drops 11.55 hPa per minute. If you've ever flown a plane you know there are no visible signs, however your body does react to some level - yet this is mainly due to significant overall change in pressure. If your process of bubble split is gradual as I suggest and takes about 1.5 second the pressure drop rate will be comparable to that in a plane but due to the extremely small pressure difference and time of it, it will go totally unnoticeable to anyone. It is also not going to affect any equipment.

The interesting side effect is that the phenomenon will cause some kind of time turbulence while moving bubble to a different time plane but there is your hand-wave area as this is something due to the mechanics of your process and you can decide on the impact of it yourself (e.g. the time might fluctuate for a moment near the bubble so you can notice a clock seconds hand stops for 2 seconds rather than 1 only to jump twice in the next second.

Some links to back this up

Improve this answer
$\endgroup$

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .