If our universe is in a state of false vacuum, and if it tunnels into a lower energy state, the most probable scenario is that all know particles and forces would be completely transformed which would result in the total devastation of all current structures (atoms, planets, stars, galaxies, etc) and the extinction of all life forms.

But I've thought that maybe, if the new energy state is not too far away from the old energy state, it could be possible that the changes are not that enormous and that all life doesn't get entirely eradicated.

And here comes my question: If our universe nucleated into a lower and more stable energy state without completely annihilating us all, what could be the possible effects of all the physical constants getting slightly altered?

Here are a few possible effects to get you started:

  • Stars could begin to burn their fuel quicker than before and their life expectancy might be dangerously reduced.
  • The Sun's radiation spectrum could be shifted, it could begin to radiate in either infrared or ultraviolet instead of visible light which would make every living beings on Earth lose their sight.
  • Likewise, sounds frequencies might also be shifted, which would mess up the hearing sense of all living beings on Earth.
  • Bodies in orbit around stars could see their orbits become unstable, they could end up crashing in their stars or get ejected far away. Same thing for moons in orbit around planets.
  • Neutron stars and perhaps also white dwarfs could instantly collapse and become black holes.
  • Previously unstable atoms might become stable. And the half-life of radioactive atoms could get increased.
  • The temperature of all matter could be slightly altered, which could lead on Earth to a new ice age or to a dramatic rise in sea levels.
  • A slight decrease in the mass of some particles might increase the expansion rate of our universe, which could lead all galaxies to quickly break apart and dissolve.
  • A slight increase in the mass of some particles might make our universe stop expanding and instead begin to collapse in a Big Crunch.
  • $\begingroup$ This might have more specific answers if asked in physics, because you're really asking what our current models predict it will do (we've never actually done it). However, one of the general agreements is that any tiny change in the constants would have such spectacular effects on the world that the lifeforms would likely be so exotically different than ours that it'd be really hard to describe the world they live in. $\endgroup$
    – Cort Ammon
    Commented Mar 30, 2015 at 17:16
  • $\begingroup$ I think in Physics you'd get the answer that this isn't possible because it hasn't already happened. All states below the current state are filled, and you can't make the things filling those states just go away. $\endgroup$
    – Oldcat
    Commented Mar 30, 2015 at 17:48
  • $\begingroup$ And even if it is possible for the universe to go into a lower energy state, lifeforms are some of the most complex and fragile structures in existence. A change that would leave them still functioning while also having immediately noticable effects on the rest of the universe is all but inconceivable. $\endgroup$
    – Saidoro
    Commented Mar 30, 2015 at 18:18
  • $\begingroup$ I may or may not write up an answer, but I highly recommend this paper by Coleman and De Luccia. $\endgroup$
    – HDE 226868
    Commented Mar 30, 2015 at 20:37
  • 1
    $\begingroup$ While this is an interesting question, really it's just so many different questions that it will be very hard to answer well. Even the answer by HDE below only covers part of it. $\endgroup$
    – Tim B
    Commented Apr 2, 2015 at 15:35

1 Answer 1


Part of me thinks this is too broad while part of me doesn't. See, there are so many different physical constants in the universe: $c$, $\sigma$, $\alpha$, $\epsilon$ . . . You get the idea. Change any of them and something odd will happen. Mess up the fine-tuning and something bad will happen. And that's the gist of the whole thing: Change something very small - such as the mass of the top quark - and things can get very messy very quickly.

So I could choose to analyze any or all of these constants, and I would rapidly run out of room, especially given my inability to be concise. But I've done a bit of reading, and I think I know how I can narrow it down (for some interesting papers, none of which I've gotten through much of yet, see Coleman (1977)1 and Matusmoto et. al. (2010); see also this answer and this question on Physics.SE, and links therein).

The most important (in this case) paper I found was Coleman & De Luccia (1980). It investigates the effects of gravity upon a false vacuum. It seems trivial until you get to this part:

At first glance, this seems a pointless exercise. In any conceivable application, vacuum decay takes place on scales at which gravitational effects are utterly negligible. This is a valid point if we are talking about the formation of the bubble, but not if we are talking about its subsequent growth.

So what governs the global evolution of the bubble? Gravity. Let me see what I can work through to show the point.

Take a scalar field, $\phi$. There is energy associated with any location in the field. To analyze this field, we can take its action, $S$. In this case, $S$ depends on the Lagrangian, $L$. Using Coleman and De Luccia's notation, $$L=\frac{1}{2} (\partial_{\mu} \phi)^2-U(\phi) \tag{1}$$ Here, we use the convention where $\partial_x$ denotes taking the partial derivative with respect to $x$. This is a simple Lagrangian, like a particle moving in a gravitational field (with very small changes in $y$, because then $g$ would vary greatly): $$L= \frac{1}{2}mv^2-mgy$$ So we can take the action using $(1)$: $$S = \int d^4x \left(\frac{1}{2} (\partial_{\mu} \phi)^2-U(\phi)\right) \tag{2}$$ The defining feature of $\phi$ is that it has two relative minima. These correspond to a false vacuum and a real vacuum - although the "real" vacuum could also be a false vacuum, simply at a lower energy state.

The thing is, if we consider gravity, then we insert a few additional terms into the action. It becomes $$S = \int d^4x \sqrt{-g} \left(\frac{1}{2}g^{\mu \nu} \partial_{\mu} \phi \partial_{\nu} \phi - U(\phi) - \frac{R}{16 \pi G} \right) \tag{3}$$ If you're familiar with the basics of general relativity, then this should remind you of the Einstein-Hilbert action: $$S_{\text{EH}} = \int d^4x \sqrt{-g} \frac{R}{16 \pi G}$$ So our Lagrangian is really similar to a mash-up of those two. Well, not really. But close.

The point is, by modifying this action, we've introduced an additional term (well, we've done more than that). We've put in a new cosmological constant. This is crucial. We can figure out the equations of motion without making the modifications and then with modifications. The difference is that the bubble can grow or shrink in different ways.

Sections II and III aren't important at the moment, and as the authors write,

We have tried to write it in such a way that it will be intelligible to a reader who has skipped the intervening sections.

Taking that to heart, we can go to Section IV.

Take a hyperboloid defined by an expression of $\Lambda$. Starting from the metric $$ds^2 = d \tau^2- \rho (i \tau)^2 (d \Omega)^2$$ where $d \Omega$ is hyperbolic, Coleman and De Luccia show that an FLRW metric can be constructed for the universe. I won't go through the derivation, because it's not conceptually important, but the metric is $$ds^2 = d \tau^2 - \Lambda^2 \sin^2 (\tau / \Lambda)d \Omega^2 \tag{4}$$ This universe will either expand or contract. Looking at earlier relations given, it is clear that this is influenced by, among other things, $G$.

Gravity doesn't influence a lot of the processes in the false vacuum, but it influences some.

For some information on what things would be like in a normal universe with a small change in $G$, see my answer here. Other great answers to a slightly different question can be found here. In summary, the most important effect of a change in a constant would be a change in $G$, which could stabilize the false vacuum and influence (a little) its growth rate.

1 Coleman and De Luccia originally investigated false vacuum scenarios, though Coleman is considered by some to have priority.


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