# What happens in a universe with only one object as time goes to infinity?
**URL:** https://boards.straightdope.com/t/what-happens-in-a-universe-with-only-one-object-as-time-goes-to-infinity/947959
**Category:** Factual Questions
**Created:** [August 3, 2021, 11:54am UTC](https://boards.straightdope.com/t/what-happens-in-a-universe-with-only-one-object-as-time-goes-to-infinity/947959 "2021-08-03T11:54:26Z")
**Posts on this page:** 13
**Page:** 1
### Author:  [@kanicbird](https://boards.straightdope.com/u/kanicbird)
#### Post date: [August 3, 2021, 11:54am UTC](https://boards.straightdope.com/t/what-happens-in-a-universe-with-only-one-object-as-time-goes-to-infinity/947959/1 "2021-08-03T11:54:26Z")
Besides the case of that object being/becoming a blackhole. Perhaps a moon or planet sized object in a universe with nothing else in it. Assuming a universe with laws like ours. Will it somehow evaporate away over time with some sort of quantum decay or stay a frozen mass forever? Could Hawkins radiation work using another force (strong, weak, EM) other than gravity to evaporate it?
I guess it would rip itself apart if it’s the only mass, but besides the case of the expanding/changing spacetime what happens?
---
### Author:  [@am77494](https://boards.straightdope.com/u/am77494)
#### Post date: [August 3, 2021, 12:05pm UTC](https://boards.straightdope.com/t/what-happens-in-a-universe-with-only-one-object-as-time-goes-to-infinity/947959/2 "2021-08-03T12:05:31Z")
Not a physicist, but child prodigy/ Nobel Laureate Chandrasekhar worked on this problem and there is the Chandrasekhar limit : Stars with mass more than 1.4 Solar Mass will burst into Super Novae while the ones with less mass will remain white dwarfs forever
---
### Author:  [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)
#### Post date: [August 3, 2021, 1:47pm UTC](https://boards.straightdope.com/t/what-happens-in-a-universe-with-only-one-object-as-time-goes-to-infinity/947959/3 "2021-08-03T13:47:07Z")
> **[Future of an expanding universe | Matter decays into iron](https://en.wikipedia.org/wiki/Future_of_an_expanding_universe#Matter_decays_into_iron)**
>
> In 101500 years, cold fusion occurring via quantum tunneling should make the light nuclei in stellar-mass objects fuse into iron-56 nuclei (see isotopes of iron). Fission and alpha particle emission should make heavy nuclei also decay to iron, leaving stellar-mass objects as cold spheres of iron, called iron stars. Before this happens, in some black dwarfs the process is expected to lower their Chandrasekhar limit resulting in a supernova in 101100 years. Non-degenerate silicon has been calcu
I know the article says stellar-mass objects, but I don’t see why it shouldn’t apply to smaller ones.
---
### Author:  [@gnoitall](https://boards.straightdope.com/u/gnoitall)
#### Post date: [August 3, 2021, 2:30pm UTC](https://boards.straightdope.com/t/what-happens-in-a-universe-with-only-one-object-as-time-goes-to-infinity/947959/4 "2021-08-03T14:30:08Z")
It doesn’t apply to an object smaller than stellar mass because the “iron star” is the core of a dead star, which by definition is stellar-mass. The iron is produced by nuclear fusion, which requires stellar mass and its gravity to proceed.
A loaf of bread left alone in an empty universe will not spontaneously collapse into a lump of iron, no matter how long you leave it alone.
---
### Author:  [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)
#### Post date: [August 3, 2021, 2:32pm UTC](https://boards.straightdope.com/t/what-happens-in-a-universe-with-only-one-object-as-time-goes-to-infinity/947959/5 "2021-08-03T14:32:48Z")
> **[Iron Stars at Eternity’s End](http://beyondearthlyskies.blogspot.com/2013/04/iron-stars-at-eternitys-end.html?m=1)**
>
> Stars generate energy and fuse lighter elements into heavier ones through nuclear fusion. The majority of stars produce energy by fusing hy...
---
### Author:  [@gnoitall](https://boards.straightdope.com/u/gnoitall)
#### Post date: [August 3, 2021, 2:40pm UTC](https://boards.straightdope.com/t/what-happens-in-a-universe-with-only-one-object-as-time-goes-to-infinity/947959/6 "2021-08-03T14:40:14Z")
The main problem is that your cite isn’t relevant to the OP’s hypothetical, which is a single isolated object of **substantially less than stellar mass**.
> [@kanicbird](#):
>
> Perhaps a moon or planet sized object in a universe with nothing else in it.
So the grand sweeping cosmological answers don’t apply, because cosmology assumes that less-than-stellar-mass concentrations of matter will eventually be consumed by stars. In OP’s hypothetical, that can’t happen.
---
### Author:  [@RitterSport](https://boards.straightdope.com/u/RitterSport)
#### Post date: [August 3, 2021, 2:42pm UTC](https://boards.straightdope.com/t/what-happens-in-a-universe-with-only-one-object-as-time-goes-to-infinity/947959/7 "2021-08-03T14:42:01Z")
I thought, given infinite time, fusion and fission will happen to all matter that isn’t iron anyway, until it’s all iron. Does any element have a half-life approaching infinity?
---
### Author:  [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)
#### Post date: [August 3, 2021, 2:42pm UTC](https://boards.straightdope.com/t/what-happens-in-a-universe-with-only-one-object-as-time-goes-to-infinity/947959/8 "2021-08-03T14:42:18Z")
> [@gnoitall](#):
>
> The main problem is that your cite isn’t relevant to the OP’s hypothetical, which is a single isolated object of **substantially less than stellar mass**.
And _I_ am saying that ut should wirk for a planet or loaf of bread, too. Which is what I _said_.
---
### Author:  [@gnoitall](https://boards.straightdope.com/u/gnoitall)
#### Post date: [August 3, 2021, 2:58pm UTC](https://boards.straightdope.com/t/what-happens-in-a-universe-with-only-one-object-as-time-goes-to-infinity/947959/9 "2021-08-03T14:58:58Z")
The only mention of substellar masses (planet, moon, loaf of bread) in the wiki article is in the section about how it goes if protons and neutrons can decay:
> **[Future of an expanding universe | Nucleons start to decay](https://en.wikipedia.org/wiki/Future_of_an_expanding_universe#Nucleons_start_to_decay)**
>
> Neutrons bound into nuclei are also suspected to decay with a half-life comparable to that of protons. Planets (substellar objects) would decay in a simple cascade process from heavier elements to hydrogen and finally to photons and leptons while radiating energy.
> If the proton does not decay at all, then stellar objects would still disappear, but more slowly. See § Future without proton decay below.
> Shorter or longer proton half-lives will accelerate or decelerate the process. This means that ...
> [@](#):
>
> Neutrons bound into nuclei are also suspected to decay with a half-life comparable to that of protons. Planets (substellar objects) would **decay in a simple cascade process from heavier elements to pure hydrogen while radiating energy**
The other half of the wiki (if nucleons don’t decay) and the other article doesn’t address substellar objects at all.
Fusion, even quantum tunneled cold fusion, requires some force to bring nuclei into proximity for fusion to occur (to overcome repulsion). In nature, that has to be gravity, and that requires a minimum mass: stellar mass.
---
### Author:  [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)
#### Post date: [August 3, 2021, 3:12pm UTC](https://boards.straightdope.com/t/what-happens-in-a-universe-with-only-one-object-as-time-goes-to-infinity/947959/10 "2021-08-03T15:12:26Z")
It is conjectured that protons and neutrons will decay with a half-life in excess of 10^{30} years. If that is correct, then the universe will be full of electrons, quarks, and other subnuclear particles. All black holes will have long since decayed via Hawking radiation. This process is expected to take something like 10^{120} years,
---
### Author:  [@Chronos](https://boards.straightdope.com/u/Chronos)
#### Post date: [August 3, 2021, 4:41pm UTC](https://boards.straightdope.com/t/what-happens-in-a-universe-with-only-one-object-as-time-goes-to-infinity/947959/11 "2021-08-03T16:41:49Z")
What process would take 10^120 years? The largest known black holes would take “only” around 10^97 years, and I don’t know of anything that would take longer.
---
### Author:  [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)
#### Post date: [August 4, 2021, 3:38pm UTC](https://boards.straightdope.com/t/what-happens-in-a-universe-with-only-one-object-as-time-goes-to-infinity/947959/12 "2021-08-04T15:38:42Z")
For all the nucleons to decay (assuming half-lives on the order of 10^{30} years. Yes, 10^{30} is an infinitesimal fraction of 10^{97}, but there are an _awful_ lot of protons and neutrons around. And only half decay in one half-life.
---
### Author:  [@TheGunIsMightierThanThePen](https://boards.straightdope.com/u/TheGunIsMightierThanThePen)
#### Post date: [August 4, 2021, 4:46pm UTC](https://boards.straightdope.com/t/what-happens-in-a-universe-with-only-one-object-as-time-goes-to-infinity/947959/13 "2021-08-04T16:46:09Z")
Huh? The number of protons in the observable universe is around the order of 1080. The number of halvings needed to bring that number below 1 is roughly log2(1080) ≈ 266.
Then the time required is 266 x 1030 years ≈ 2.66 x 1032 years, way off from either 1097 or 10120 years.