The following is an extract from our Lost in Space-Time newsletter. Each month, we hand over the keyboard to a physicist or mathematician to tell you about fascinating ideas from their corner of the universe. You can sign up for Lost in Space-Time here.
As an astrophysicist, I spend a lot of time thinking about nothing. Literally. The question of why there is âsomethingâ instead of ânothingâ truly keeps me awake many nights â but I draw solace from knowing that thinkers have wrestled with this topic for perhaps as long as there have been thinkers to wrestle with it. Somehow, knowing the possible futility isnât sufficient to deter my mind from going down this rabbit hole, and I donât think Iâm alone.
Before we can get into if or how something might come from nothing, we need to take a step back and talk about ânothingâ with more precision. When I teach a course on this, we spend an entire class period talking about nothing, for which I am sure there are cynics questioning the use of tuition dollars. However, the thing is, there are different types of nothing. Many categories of nothing have been expounded on in academic discussions, but I will limit us to three main types here.
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The most trivial type of nothing in this scheme is type 1, which is what I suspect many people first picture when they think of ânothingâ. In this case, we have a turnkey universe ready for inhabitants to move in, but there just isnât anything in it â no matter, no energy and no force fields. To be clear, we canât achieve this type of nothing in a lab: even in the most extreme ultravacuum chambers, there are still fields that permeate space that we canât avoid (at least not yet).
Type 2 nothing actually turns nothingness up a notch â in this case, we no longer have the fabric of space-time. In a real estate analogy, it would be like having a permit to build a house but not yet having the land on which to build it. There are, however, a whole mess of zoning regulations that determine what can be done. This type of nothing no longer has âthingsâ in it or an arena in which there could even be things, but it does have underlying laws that inform what could possibly exist.
This type of nothing overtly raises the question: where do these laws reside if they donât have a universe to reside in? One can imagine a higher power in the context of type 2 nothing, and they might determine what is and isnât possible â in other words, the laws that govern the universe reside with them. This is, indeed, the perspective of many theologies and may well be correct for all I know. But if it is, then we have only managed to nudge the philosophical can down the road â even a higher power is âsomethingâ, so we still have something instead of nothing.
The most extreme type of nothing is type 3: no things, no fields, no arena and no underlying framework or set of laws. It is truly a complete and utter void that defies language â even calling it a âvoidâ might suggest that there is something that is empty. This type of nothing is the most challenging to reconcile with the fact that there is now (demonstrably) something for us to make for dinner. In this type of nothing, it isnât clear that there is even room for a higher power â because that wouldnât be nothing.
I want to pause here and bring up a curious feature of the observable universe, the universe full of âsomethingâ. Letâs imagine for a moment that you want to buy a car, but you have no money. A very kind and generous friend loans you the money with no interest and you buy the car. Now you have it, but you owe your friend exactly the amount of money that the car is worth. So, in some very real sense, your net worth is zero. It turns out the universe is in a similar situation.
The ânet worthâ of the observable universe appears to be effectively zero, or as close to zero as we can determine. We can estimate the entire mass and energy of the observable universe â which is positive â and we can estimate the entire gravitational potential energy of the universe â which is negative â and these two seem to cancel each other out. If the universe has a net worth of nothing, then instead of asking, âWhy do we have something instead of nothing?â, the question becomes, âWhat was the mechanism for the loan that allowed the universe to come into being?â.
The general tactic scientists have used here is to consider the physics of the universe as we understand it and try to extrapolate possibilities that could have led to such a loan. Options have included quantum fluctuations, ekpyrotic scenarios, black hole cosmologies, cyclic expansions and contractions and the âno boundaryâ model proposed by physicists Stephen Hawking and James Hartle. Notably, however, none of these options gets us to a type 3 kind of nothing. In fact, none of these even really achieves a type 2 nothing.
Of course, there is also the argument that âsomethingâ is the natural state instead of ânothingâ, and we just need to accept that. However, to me, this has a âjust because I said soâ vibe that doesnât pass muster â not to mention the questions it invites along the lines of, âWhy this particular type and amount of something and not something else?â.
We are clearly on the borderlands of science here. Not only is the physics of this uncharted and potentially un-chartable, but I end up tangled in philosophical knots. It is clear to me that my own intellect isnât up to the task â there is an inherent problem embedded in the infinite regression we encounter here that has no apparent solution that I can convince myself of. For this reason, I am often tempted to punt this issue as beyond human comprehension, and therefore into the realm of the supernatural.
Then another voice in my mind speaks up to remind me that just because I donât understand something, it doesnât mean it isnât understandable. I am reasonably sure that there is just no way I could teach my dogs to understand general relativity. Heck, even thermodynamics would be a stretch â once I brought helium-filled balloons home for a party and one of my cats at the time absolutely lost his mind in terror. It seemed obvious to my husband and me that Jinkoâs feline brain was thinking along the lines of: âThose things that float around the house violate the laws of nature.â
Here we are with our limited human brains. This is a good time to remind ourselves of the âGod of the gapsâ fallacy. Simplified, this fallacy goes: âIf I donât understand something, it must be due to a supernatural being.â Of course, it is worth keeping in mind that the inverse is also true: just because we think we understand something doesnât mean it isnât supernatural.
The late author and futurist Arthur C. Clarke had three adages that informed his thinking, now known as Clarkeâs three laws. These laws often come to mind when I am considering the something-from-nothing enigma:
- When a distinguished but elderly scientist states that something is possible, [they are] almost certainly right. When [they state] that something is impossible, [they are] very probably wrong.
- The only way of discovering the limits of the possible is to venture a little way past them into the impossible.
- Any sufficiently advanced technology is indistinguishable from magic.
I think we would be well-advised to keep these adages in mind as we consider why we have something instead of nothing, and scientists shouldnât be let off the hook just because the science of today isnât up to the task. Science itself has led us to the precipice of perhaps the greatest existential mystery, one that has impelled human thought and belief for uncounted generations.
To be sure, thinking about why we have something instead of nothing brings us to the outer limits of what is currently (and possibly ever) accessible to science. In fact, at times in the universe earlier than the Planck time of 10-43 seconds after the universe came into being â when we already have something, however strange and small â our current understanding of physics breaks down. At even earlier times, which are out of reach from empirical inquiry, our hypotheses are squarely in the realm of philosophy and theology and are, I suspect, likely to remain so for the foreseeable future.
That being said, we never know when a new breakthrough might shatter a barrier we thought we had, and there may well be aspects of the something-from-nothing mystery that will be accessible to empirical inquiry of the future.
