# The science of the reverse bobble **URL:** \ **Category:** Factual Questions\ **Created:** [June 20, 2021, 2:35am UTC](https://boards.straightdope.com/t/the-science-of-the-reverse-bobble/944666 "2021-06-20T02:35:41Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [June 20, 2021, 2:35am UTC](https://boards.straightdope.com/t/the-science-of-the-reverse-bobble/944666/1 "2021-06-20T02:35:41Z")
For those not familiar with it, a bobble is a thing in some Vernor Vinge books. A perfectly smooth sphere, it is impervious, indestructable, and 100% perfectly reflective to all radiation. It can be produced to last for an arbitrarily long time, and the flow of time is 100% stopped inside of it. My mind wanders occasionally towards what would happen in a “reverse bobble”, where time inside passes at an arbitrarily accelerated rate. (I know that pockets of accelerated time have been used in SF many times, but I’m not sure if any have given it deep consideration.) This object has the same 100% perfect reflectivity–nothing, including any form of radiation or kinetic energy from inside can pass to the outside environment, and vice-versa (not even neutrinos). Say that you set the bobble to last a trillion years on the inside while one second passes outside. Say that it is a bobble on a random patch of ground, half the volume soil, half air. At first thought, you might think that with no heat input from outside, the temperature inside would plunge to nearly absolute zero. But then, if the shell has absolute perfect reflectivity (and not 99.999999999%) then none of the heat originally inside can leave, so maybe the overall internal system can’t become colder? And all of the chemical reactions that can take place in a dark, closed space will continue to happen: the plants will quickly die, heterotrophic life such as fungi and bacteria will continue to metabolize until some aspect of internal conditions makes it impossible. Over the trillion years any short or long term unstable chemical bonds are going to break apart. And any radioactive atoms except for those with incredibly long half-lives will decay. Given those conditions, what should you expect to find/experience when the bobble releases. Will it be like a puff of warm air, an oven door opening, a conventional explosive, a nuclear bomb? Will a trillion years be enough for all the decay products from radioisotopes to have reached a stable, non-radioactive end stage? Including absorbing all the neutrinos bouncing around in there? Obviously different materials would produce different results–a reverse-bobble full of yellow-cake uranium would be far more deadly than one full of glacial ice, for example. But how inert would the substance need to be before the debobbling becomes excessively interesting? ---
**Author:** ![k9bfriender](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/k9bfriender/32/3283_2.png) [@k9bfriender](https://boards.straightdope.com/u/k9bfriender)\ **Post date:** [June 20, 2021, 3:16am UTC](https://boards.straightdope.com/t/the-science-of-the-reverse-bobble/944666/2 "2021-06-20T03:16:03Z")
Depends on what exactly you have in there. Let’s assume about a ton of soil, I don’t think that the air is going to matter much. Average is about 3ppm uranium and 6ppm of thorium. There’d be a bit of carbon-14, but it’s not much, and I don’t think that it would be a large contribution, less than one in a trillion carbon atoms, and carbon-14 doesn’t give off all that much in the decay. There’s not nearly enough time for any significant proton decay, so I don’t think that that needs to factor in. So, we are basically looking at a bit under a gram of uranium and thorium. I think that those will be by far the largest contributors. The math requires quite a bit of cross referencing, so I hope I got the numbers at least close to right here. You would go from uranium and thorium with a binding energy of 1800 MeV or so, to iron with a binding energy of under 500 MeV. You’d have somewhere in the 10^23ish particles, each losing around 1300 MeV, which comes to somewhere around 10^14ish joules. One kiloton of TNT is about 10^12 joules, so what you have here is a 100 kiloton bomb. There’s a few estimations in there, so I wouldn’t be surprised if I’m off by an order of magnitude or more, but suffice to say, I wouldn’t open it up near anything I cared about. ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [June 20, 2021, 3:25am UTC](https://boards.straightdope.com/t/the-science-of-the-reverse-bobble/944666/3 "2021-06-20T03:25:22Z")
Given enough time the precise nature of the elements and compounds you start with doesn’t matter. Get past the expected lifetime of protons and you will open up a bobble filed with an amorphous fog of photons. Information conservation suggests that something about the photon fog would have some tiny lack of isotropy, but not in any meaningful or recoverable way. Overall you get a mini heat death universe. But one where space didn’t expand. Well we assume it didn’t. Once we posit impossible physics we can do anything we like. Maybe the bobble encapsulates expanding space time too. ---
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [June 20, 2021, 3:29am UTC](https://boards.straightdope.com/t/the-science-of-the-reverse-bobble/944666/4 "2021-06-20T03:29:59Z")
In “The Long Arm of Gil Hamilton” by Larry Niven, the bad guy was able to murder some people by turning on his accelerated time field and shining an ordinary flashlight which got blue-shifted into some sort of death ray as it left the field, or something. But that was a slightly different impossible tech, since there was no perfect reflectivity that I can recall. ---
**Author:** ![k9bfriender](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/k9bfriender/32/3283_2.png) [@k9bfriender](https://boards.straightdope.com/u/k9bfriender)\ **Post date:** [June 20, 2021, 3:30am UTC](https://boards.straightdope.com/t/the-science-of-the-reverse-bobble/944666/5 "2021-06-20T03:30:28Z")
> [@Francis\_Vaughan](#): > > Get past the expected lifetime of protons and you will open up a bobble filed with an amorphous fog of photons. The lower bound on the half-life of protons is 10^39 years. Assuming that it’s that low, at the time difference the OP describes, it would still take 10^20 years for half of them to decay. > [@Francis\_Vaughan](#): > > Once we posit impossible physics we can do anything we like. Maybe the bobble encapsulates expanding space time too. That would be interesting as well. If you were able to speed things up to get a significant amount of spatial expansion within the field, opening it could do _interesting_ things. ---
**Author:** ![k9bfriender](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/k9bfriender/32/3283_2.png) [@k9bfriender](https://boards.straightdope.com/u/k9bfriender)\ **Post date:** [June 20, 2021, 3:31am UTC](https://boards.straightdope.com/t/the-science-of-the-reverse-bobble/944666/6 "2021-06-20T03:31:37Z")
You could also reach into it, as someone discovered when they reached in and their arm had died and decayed before they could pull it back out. Been a long time since I read those, but I think that was how he tracked down a criminal, that they had a newly grown arm, although less new than one would expect, given that the criminal spent 6 months in accelerated time to allow it to grow. BTW, that’s the first thing I thought of when I read the OP as well. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [June 21, 2021, 5:34pm UTC](https://boards.straightdope.com/t/the-science-of-the-reverse-bobble/944666/7 "2021-06-21T17:34:41Z")
In addition to the Niven device, Charles Stross’ novel “The Iron Sunrise” starts with someone aging the center of a star a few quintillion years. This has bad effects later on, when the aging field is turned off, and the rest of the star finds that its previously lively core is stone-dead. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [June 21, 2021, 7:26pm UTC](https://boards.straightdope.com/t/the-science-of-the-reverse-bobble/944666/8 "2021-06-21T19:26:15Z")
> [@Andy\_L](#): > > In addition to the Niven device, Charles Stross’ novel “The Iron Sunrise” starts with someone aging the center of a star a few quintillion years. Yes, but that wasn’t a closed system–the heat and radiatiin leaked away into the pocket universe. ---
**Author:** ![Andy\_L](https://avatars.discourse-cdn.com/v4/letter/a/c67d28/32.png) [@Andy\_L](https://boards.straightdope.com/u/Andy_L)\ **Post date:** [June 21, 2021, 8:04pm UTC](https://boards.straightdope.com/t/the-science-of-the-reverse-bobble/944666/9 "2021-06-21T20:04:33Z")
That’s right - sorry about that. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [June 21, 2021, 8:12pm UTC](https://boards.straightdope.com/t/the-science-of-the-reverse-bobble/944666/10 "2021-06-21T20:12:18Z")
But a stellar core in a reverse bobble would be interesting. No heat would escape, so it would get hotter and hotter, cooking up elements that a “naked” one wouldn’t.