The Two Big Bangs (Synopsis)

“These theories were based on the hypothesis that all the matter in the universe was created in one big bang at a particular time in the remote past.” -Fred Hoyle

It's making headlines everywhere we go: the recent paper stating that quantum equations prove that there is no Big Bang.

Image credit: ESA/Hubble & NASA; Acknowledgement: Judy Schmidt. Image credit: ESA/Hubble & NASA;
Acknowledgement: Judy Schmidt.

Is that even possible? Honestly, it depends on which definition of the Big Bang you're using. As it turns out, there are two of them, and there's a good (historical) reason for that. But in the context of what we know today, one of them isn't a good definition anymore, and hasn't been for decades.

Image credit: ESA and the Planck collaboration, modified by me. Image credit: ESA and the Planck collaboration, modified by me.

Come find out what this all means, and whether it's possible that the Big Bang never happened. (Hint: it did!)


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THANK YOU. The instant I read the word "singularity" in that article red sirens started going off in my head. Of course 100% of the credit for that goes to all of the articles you've written clarifying the way-more-confusing-than-it-needs-to-be subject of the Big Bang. Can we please just rename the damn thing?

By Alex Beachum (not verified) on 10 Feb 2015 #permalink

Holy cow, Ethan, thanks again for going into this topic in more depth.

Definition (1), "The hot, dense, expanding state that our observable Universe emerged from, that expanded, slowed, cooled, and gave rise to elements, atoms, stars, molecules, planets, and eventually us," is more intuitively accessible, as it appears to assume that spacetime always existed in some way, but its contents (energy, matter) changed over time.

Definition (2) "The initial singularity that represents the birth of space and time," is one that I basically had to accept as a given or "on faith" as it were (trust in the process that led to that theory being accepted), as it was somewhat counterintuitive.

But now it turns out, if I understand you correctly, that (1) is more likely correct and is backed up with enough observations & theory to render (2) obsolete. OK, that's an "easy" adjustment in worldview to make.

I take it that (1) is also compatible with the Tegmark multiverse, by way of universes arising from infinitesimal but nonzero points in the multiverse? Would the purported mechanism be something like vacuum collapse or false vacuum collapse?, or something else?

Wild question dep't: What conditions would have obtained in the universe at an ambient temperature of about 300 Kelvin, in particular re. the formation of somewhat complex molecules? And for how long do we think the mean ambient temp was in the range of about 250 - 350 K? (What'up with this: I read somewhere, possibly in one of your columns, that there would have been a point in the development of the universe, at which ambient conditions might have been favorable to the existence of biologically-relevant molecules. If any such molecules formed and were evenly dispersed as the universe expanded, that might be a path toward greater uniformity in biology across the universe.)

Is vacuum energy (either high as it was during inflation or low as it is for dark energy today) thought to be a quantum field like those we're familiar with for "normal" matter and energy? If so, do we have any ideas about how exactly it couples to one or more of the fields we're more familiar with? (As it seems it must have at the end of inflation.) Would there be a particle that'd be a quantum of that field, and could we create and detect one with a powerful enough accelerator?
Or would vacuum energy be more akin to the energy carried by gravitational waves, requiring a more complete theory of quantum gravity to explain its coupling?


What conditions would have obtained in the universe at an ambient temperature of about 300 Kelvin, in particular re. the formation of somewhat complex molecules? And for how long do we think the mean ambient temp was in the range of about 250 – 350 K?

I tried to look this up but didn't look very deeply. This source says there was a "habitable epoch" around 10-17 my after the big bang, which I take to mean an epoch in which temperature was low enough to allow for chemical bonds to form. However, that same source says the first stars ignited 560 my after the big bang while this source says the first stars formed 100-200my after the big bang. Either way, without stars there would've been effectively no elements heavier than Li with which to form compounds. So I think the most likely answer to your question is: there were no molecules more complext than LiH and H2 during the period when the universe was that temperature, because no elements other than H, He, and Li existed in significant amounts yet.
Other folks, feel free to correct me if I'm wrong.

Anyone here old enough to remember rabbit ears for the TV?
Remember how the TV when not dial'ed in to the proper frequency was nothing but static? However, once you hit the PRECISE FREQUENCY, comprehensible information flowed?

We need a tuner on this.

By Ragtag Media (not verified) on 11 Feb 2015 #permalink

Eric @ 4: Thanks for checking. What I was after with that question, was any basis for uniformity at the starting stages of biology. But a clear No is as good as a clear Yes, and I'll look forward to humans landing on Mars and looking for any evidence of bacteria.

@6: well, it might be uniform. Lots of biology might have started at time t, where t = "about half a billion years after the formation of the first solar systems to form after the first generation of stars went supernova." But we don't have any good way to check that. At least not yet.

Actually, if you're including basic organic chemistry under the heading "biology," then it could be significantly earlier than what I described in @7. AIUI, organics probably formed in the wake of the first supernovas, before second-generation solar systems formed.

Perhaps it should be time-out; the universe has been here a long time, we don't need to solve its mystery overnight. We need a pause and ask, are we trying to measure the infinite with the finite? The question is not whether the Big Bang occurred, but whether we even have the mathematical tools necessary to explore the geometry of the universe.

"You won’t be alone, but wouldn’t you rather be right?" But then you wouldn't be a scientist.

Not a scientist here so excuse my unscientific manner, but it seems to me this whole subject is a defensive maneuvere to deal with the troubling problem of what was there before the Big Bang. The average Joe simply will never be convinced Something sprang out of Nothing. Doesn't happen ... especially randomly. Hawking recently disavowed God for the simple, and I'd say ridiculous reason the God would need time to operate out of to perform the Big Bang and time didn't exist until after it.

The Bible describes the Big Bang in Gen. 1:1 ("In the beginning God created the heavens ...") and it also gives us a peak into the scene before that in John1:1, another "In the beginning" where we see "In the beginning was the logos."

This "logos" can be described in many ways -- as word, logic, law, even ratio -- but it makes a whole heck of a lot more sense than Nothingness.

but it seems to me this whole subject is a defensive maneuvere to deal with the troubling problem of what was there before the Big Bang.

Seems to me that this is more likely caused by your

Not a scientist here

But go ahead, tell us what t<0 means in reality.

Hint: it would be as correct to use that reasoning in explaining what "minus three apples" means when you hold those minus three apples in your hand.

It's easy to explain AS AN ABSTRACT what those "real" negatives are, but much harder to explain them as realities rather than privatives, which don't exist.


(of an action or state) marked by the absence or loss of some quality or attribute that is normally present.

So lets go on in the meantime with the rest of your comment:

The Bible describes the Big Bang in Gen. 1:1 <

No it doesn't. It describes creation.But in Gen 2 it talks of a different and incompatible creation. BOTH can't be right, both CAN be wrong. Moreover, it ascribes to the creator of bats that the belief by that creator that bats are birds and not, as they are in fact, mammals with flight.

So it gets biogenesis wrong too.

The average Joe simply will never be convinced Something sprang out of Nothing.

However, you do seem convinced that Something sprang out of Nothing, since that is what happens in the tales of your bible.

Are you not an average joe?

Does the average joe not believe the bible?

the truth is "believe" is all you have. And it's only there so you can stop asking questions because "you've answered it and you're not allowed to question".

Sorry, what if the Mayans were right and EVERY SINGLE BELIEVER ALIVE TODAY is therefore necessarily wrong?After all THEY had a holy book describing a creation, just like yours, that you ascribe to "The Big Bang".

If that fact along is not enough to convince you of the Mayan's believe in the ACTUAL true god, then what convinces you of your correctness? And how should *I* believe you have it right, not the extinct Mayans?

And with that you'd be treating it like science. And so far science hasn't needed the hypothesis of "Goddidit".

It clears up the inflationary period. A two-stage big bang

is this article saying the universe pre-existed (so to speak) for an infinitely long time in an inflationary energy state until it suddenly gelled into the Big Bang ... All of which is heading toward a dark, cold, evaporated ending? In other words an infinitely ageless universe is finally at the end? (In a mere few billion billion years, that is.) just trying to understand the implications.

of course, if you look at Big Bang from the point of view of causation, since any effect depends upon a previous moment of causation, no beginning can be postulated. Any moment of events depends upon previous moments of causation.

By Wilson Hurley (not verified) on 14 Feb 2015 #permalink

What cause makes a radioactive decay happen at the time that it DOES happen? Don't say "the energy difference" because that energy difference is there for (for example) uranium for all the millions of years that it exists before decaying.

So what's the CAUSE of the decay?

Or did it have no cause, merely the opportunity to happen?

In which case, the universe didn't NEED a cause, merely the opportunity.

Its more like a Big Whoosh than a Big Bang. How does a whole universe come into existence from nothing?

That's the theory of the Big Bang, Prof.

Go read it up.

What's striking for me is that many models of inflation have been implying the absence of a singularity for well over a decade, but almost all popular accounts still use the singular Big Bang concept. Unfortunately the notion that there was an 'explosion' at a single point is the source of a huge amount of confusion among non-physicists trying to understand this (I remember as a teenager thinking the CMB light was some form of shock front, which is, of course, completely wrong).

The problem is that we don't want to say the Big Bang is wrong, because after t=ε it works very very well. And the fact is that no-one knows what happened before t=ε anyway, so it would be a bit presumptuous. But I think the message needs to get out that there's some debate as to how long ε actually was - it's either an incredibly small fraction of a second (singularity model) or an infinite amount of time (eternal inflation).

"But I think the message needs to get out that there’s some debate as to how long ε actually was"

There is. This thread is one, for example, but it's definitely not the first even on this blog.

But if you haven't read any of the earlier ones, this will appear to be the first and only one so far. But others won't be reading THIS debate on how long the inflation time was, so next time someone will say the exact same thing as you just did when the next time it's discussed comes up.

And someone will miss *that* one.

And so it continues.

Thing is your comment is phrased negatively and that creates it as meaningless, as shown above.

Phrasing it positively and it no longer falls foul of the above scenario and it can retain utility and meaning.

Prof @18:

If when you ask "how" you mean "describe the process," Ethan has done some of that. (A really good explanation would involve more math than I ever had.)

If you mean "this doesn't make sense--convince me that it's possible," our ideas of what makes sense are suited to the scale and conditions that we and our ancestors lived in. What makes sense to us involves timescales of seconds to decades, not nanoseconds or billions of years. It involves sizes like seeds, our bodies, or distances on the surface of Earth, not single atoms or a million light-years.

Mark J @11:

The average Joe simply will never be convinced Something sprang out of Nothing. Doesn’t happen … especially randomly.

It happens all the time, just on scales humans aren't aware of. IIRC, something like 90% of the mass of the proton is due to something coming from nothing (and returning to it, constantly).
Of course we can argue whether laws of QM alone, with no matter or energy, are "nothing." But given that they are strongly confirmed while other potential causa causans are not, I don't see how we could empirically prefer any other first cause to them.

Wilson @16:

if you look at Big Bang from the point of view of causation, since any effect depends upon a previous moment of causation, no beginning can be postulated.

Not necessarily. Imagine looking backward in time at a series of causes. Imagine each previous cause takes half the time of the later one. (So, at time t the cause took 1 second, at time t-1 the prior cause took 0.5 seconds, at time t-2 the prior cause took 0.25 seconds, and so on). If that were the case, then - strange as this may sound - an infinite number of preceeding causes would take place in a finite amout of time (specifically in this case, 2 seconds). And there are many many more different solutions too. Bascially, you just need a series of causes where (a) each prior cause takes less time than the one it produces, in such a way that (b) the time relationship between such causes fulfills the requirements for a convergent series. Then the total time required for that infinite series of causes is finite. Something to think about. :)

Musings like this make me wonder why, when it comes to concepts like infinity, philosophy seems to be stuck in the early 1600s. As far as I can tell, the subject hasn't yet grappled with calculus.

@Wow #21:
I honestly have no idea what you're talking about.

The notion of eternal inflation is hardly new. And neither is the debate about it. Go and read some of Guth's papers from the '90s.

Inflation has long been accepted an an element in the singular Big Bang model. But 'Inflation' is a term that covers a multitude of different models which have evolved significantly over the past 30 years. Unfortunately the article posted here glosses over the differences between these, but then that may be inescapable given the complexities involved. It ends up addressing a specific sub-type called Eternal Inflation which is looking increasingly powerful, though it has some uncomfortable aspects.

Right now we are unable to rule out any of the leading models of primordial evolution (including the presence of a singularity), and any statement to that effect is grossly naive. If you think that's 'negative' then too bad, that's the state we're in right now. But the alternative to a singularity is certainly looking very promising, and it's time for popular explanations to incorporate it in some way.

The problem is that we just don't know what happened before a certain point in the history of the universe. The real debate is whether we ever *can* know.

I honestly have no idea what you’re talking about.

There is no simpler english that can be used, Charles. Your inability must be due to you not WANTING to get it.

You whined "We should put the debate out there!". Since it HAS ALREADY, then your complaint is bollocks. For the reason that it's bloody damn well WRONG.

IF you'd said "Nice to see the debate about it", then you wouldn't be wrong (unless you're lying about how you felt about the debate being here).

Get it now, doofus?

Right now we are unable to rule out any of the leading models of primordial evolution (including the presence of a singularity), and any statement to that effect is grossly naive.

More meaningless whining.


Any model determining that there was a singularity or not a singularity will in its description NOT INCLUDE THE OBVERSE CLAIM for damn well obvious reasons.

You're just whining for the sake of telling off people far smarter than yourself for not doing things exactly like you want them to and making up what they are doing to ensure you can make the damn claim.


1.) Could "radiation" and "matter" be flipped on your curves? The expansion of the universe was more rapid during the radiation dominated epoch - (1+z)^4 as opposed to (1+z)^3 - and this is actually important to the modeling of the Baryon Acoustic Oscillations.

2.) Even back in the 1980's, I don't think that many really considered the "Big Bang" to be a singularity, rather a hand-waving "early period when the rules of quantum gravity ruled." I am not sure things have really changed very much, even with inflation (and particularly given the lack of real observational or experimental evidence for inflation).

By Marshall Eubanks (not verified) on 26 Feb 2015 #permalink

What's unclear to me about the author's diagrams is where the "inflation" (rapid, short-lived expansion) is on his size of the universe vs. time graphs. If there was inflation at some early, brief epoch, I wouldn't expect to see the size of the universe increasingly monotonically on the yellow curves.

By Chris Anderson (not verified) on 20 Apr 2015 #permalink

Hi Ethan,

As usual, great column. I do wonder, however, at the utility of trying to fine-tune the general use of an unscientific term like "the Big Bang" to fit correct scientific discourse. The goal seems to be to de-link the general use of the term Big Bang from the ultimate origin of space and time; to acknowledge that inflation is a newer segment of knowledge. Well and good. But I have a feeling that the layman will find the notion of the primal inflation of spacetime, from the energy inherent in space itself, exciting enough to still merit the label "Big Bang," which may crimp the effort to make the fine distinction. This may be frustrating to scientists who know that the original use of "the Big Bang" didn't envisage inflation, but I suspect it will be easier to let the term, which isn't really a scientific one anyway, float to where the popular imagination has it: the beginning - and then get on with fine-tuning the actual science around inflation etc. Unless there's a catchier term to popularize?

Thanks for the great writing, as always!

By John Kane (not verified) on 05 Feb 2016 #permalink

MMmmm, that was an interesting time warp from Feb 10 last year (2015).