Category: big bang

What Really Put The ‘Bang’ In The Big Bang?

So what is it that put the “bang” in the hot Big Bang? It’s the end of inflation. There is a state prior to the start of the hot Big Bang that set it up and provided it with the initial conditions of being spatially flat, the same energy density everywhere, always below a certain threshold temperature, and uniform with quantum fluctuations superimposed atop it on all scales.

When this inflationary state ended, the process of cosmic reheating transformed that energy — which had previously been inherent to the fabric of space itself — into particles, antiparticles and radiation. That transition is what put the “bang” in the hot Big Bang, and led to the birth of the observable Universe as we know it. The details of this were first worked out in the 1980s, back when inflation was just a theoretical idea, and have been confirmed by observations taken in the 1990s, 2000s, and 2010s. For decades, scientists have known what put the “bang” in the Big Bang. At last, now the general public can share in that knowledge, too.

Last week, a story came out that claimed to discover what put the “bang” in the Big Bang. Only, the actual study talked about what occurs in a conflagration or an explosion, which is completely unrelated to anything that occurs in the earliest moments of the hot, dense state that kicked off our Universe as we know it. Fortunately, we don’t have to wonder about what put the “bang” in the Big Bang; this is something scientists have known for decades.

The answer? It’s the cosmic reheating that occurs at the end of inflation that gives rise to the first moments of the hot Big Bang. Come get the real, hype-free story today.

What Came First: Inflation Or The Big Bang?

“In fact, our entire observable Universe contains no signatures at all from almost all of its pre-hot-Big-Bang history; only the final 10^-32 seconds (or so) of inflation even leave observably imprinted signatures on our Universe. We do not know where the inflationary state came from, however. It might arise from a pre-existing state that does have a singularity, it might have existed in its inflationary form forever, or the Universe itself might even be cyclical in nature.

There are a lot of people who mean “the initial singularity” when they say “the Big Bang,” and to those people, I say it’s long past due for you to get with the times. The hot Big Bang cannot be extrapolated back to a singularity, but only to the end of an inflationary state that preceded it. We cannot state with any confidence, because there are no signatures of it even in principle, what preceded the very end-stages of inflation. Was there a singularity? Maybe, but even if so, it doesn’t have anything to do with the Big Bang.”

Have you heard that our Universe began some 13.8 billion years ago with the start of the Big Bang? There’s a good chance that some version of that story has made it to you, but it unfortunately has probably gotten to you the same way it got to me: with an error that’s many decades out of date. 

What if I told you that you couldn’t extrapolate the Universe back to a singularity, where all the matter and energy was consolidated into a space so tiny that the laws of physics break down?

What if I told you that we have a verified, validated theory of what happened before the Big Bang, and it has (for decades, now) superseded and replaced the idea of an initial singularity as the earliest stages of the Universe?

Meet cosmic inflation, the pre-origin of our Universe that set up and gave rise to the Big Bang, and learn why the naysayers are out of legs to stand on.

Was Dark Matter Really Created Before The Big Bang?

“So if that’s what the observational data points towards, what can we say about where dark matter comes from? A recent headline that made quite a splash claimed that dark matter may have originated before the Big Bang, and many people were confused by this assertion.

It might seem counterintuitive, because the way most people conceive of the Big Bang is as a singular point of infinite density. If you say the Universe is expanding and cooling today, then you can extrapolate it back to a state where all the matter and energy was compressed into a single point in space: a singularity. This corresponds to an initial start time for our Universe — the beginning of our Universe — and that’s the Big Bang.

So how could something that exists in our Universe, like dark matter, have originated before the Big Bang? Because the Big Bang wasn’t actually the beginning of space and time.”

Last month, a paper came out claiming that dark matter may have been created before the Big Bang. Although it might sound implausible, it’s absolutely a possibility that we cannot rule out, although it might be an idea that’s extraordinarily difficult to test when we compare it up against the other options. We have to keep every scenario that hasn’t been ruled out in mind, and understand that despite all we don’t know about dark matter, there’s a ton of indirect evidence brought to us by the full suite of observations at our disposal.

Could dark matter have been created before the Big Bang? Yes, but three other possibilities are maybe even more viable. Come find out why today.

Ask Ethan: Where Is The Center Of The Universe?

“I am wondering how there isn’t a center of the universe and how the cosmic background radiation is [equally] far away everywhere we look. It seems to me that when the universe expands… there should be a place where it started expanding.”

Ah, the old center of the Universe question. If the Big Bang happened a long time ago, and we see galaxies moving away from us faster and faster the farther away they are, then where did the Big Bang happen? Where did the expansion start?

It seems like such a simple question, but it turns out this is the wrong question to be asking. The way space and the expanding Universe works is very different from the picture most of us have in our heads, which is much more like an explosion than like an expansion. Yet there’s a very large suite of evidence that points us away from an explosion.

Instead of asking *where* the Big Bang occurred, we should be asking *when* the Big Bang occurred. It makes a lot more sense when you think about it in those terms. Come and find out why.

Ask Ethan: How Well Has Cosmic Inflation Been Verified?

“To what margin of error or what level of statistical significance would you say you say inflation has been verified?”

So, you’ve got an alternative theory to our best mainstream scientific ideas? Well, guess what: those are the same shoes that every scientific idea we accept today were wearing at one point in the distant past. The thing that separates them from the ideas that fell by the wayside were three remarkable feats:

1. They reproduced all the earlier successes of the previous prevailing model.
2. They resolved or explained puzzles or problems that the previous model had no sufficient answer for.
3. And, perhaps most importantly, they made new predictions that we could go out and test about the Universe, and those predictions were proven correct by the appropriate experimental or observational test.

Although most people don’t appreciate it, inflation has hurdled all three bars, and has no fewer than four spectacular predictions that have since been confirmed. Come learn how well cosmic inflation has been verified today!

Could All Our Scientific Knowledge Come Tumbling Down Like A House Of Cards?

“Now, think about what would be required to do today to tear down one of our leading scientific theories. It’s not as complicated as you might imagine: all it would take is a single observation of any phenomenon that contradicted the Big Bang’s predictions. Within the context of General Relativity, if you could find a theoretical consequence of the Big Bang that didn’t match up with our observations, we’d truly be in store for a revolution.

But here’s the important part: that won’t mean that everything about the Big Bang is wrong. General Relativity didn’t mean everything about Newtonian gravity was wrong; it simply exposed the limit of where and how Newtonian gravity was successful. It will still be accurate to describe the Universe as having originated from a hot, dense, expanding state; it will still be accurate to describe our observable Universe as being many billions of years old (but not infinite in age); it will still be accurate to talk about the first stars and galaxies, the first neutral atoms, and the first stable atomic nuclei.”

There are a great many people out there who absolutely cannot wait for the day where one of our greatest scientific theories is demonstrated to be wrong. Where an experiment or observation comes in that cannot be reconciled with our leading ideas of how the Universe works. At last, perhaps an unintuitive part of our existence, like relativity or quantum mechanics, might be replaced with something that’s a closer approximation of our actual reality. But that won’t invalidate what we already know; it will merely extend it. 

Scientific revolutions aren’t what most people think, but they are going to come, eventually. Here’s what the revolution will actually look like.

Could All Our Scientific Knowledge Come Tumbling Down Like A House Of Cards?

“Now, think about what would be required to do today to tear down one of our leading scientific theories. It’s not as complicated as you might imagine: all it would take is a single observation of any phenomenon that contradicted the Big Bang’s predictions. Within the context of General Relativity, if you could find a theoretical consequence of the Big Bang that didn’t match up with our observations, we’d truly be in store for a revolution.

But here’s the important part: that won’t mean that everything about the Big Bang is wrong. General Relativity didn’t mean everything about Newtonian gravity was wrong; it simply exposed the limit of where and how Newtonian gravity was successful. It will still be accurate to describe the Universe as having originated from a hot, dense, expanding state; it will still be accurate to describe our observable Universe as being many billions of years old (but not infinite in age); it will still be accurate to talk about the first stars and galaxies, the first neutral atoms, and the first stable atomic nuclei.”

There are a great many people out there who absolutely cannot wait for the day where one of our greatest scientific theories is demonstrated to be wrong. Where an experiment or observation comes in that cannot be reconciled with our leading ideas of how the Universe works. At last, perhaps an unintuitive part of our existence, like relativity or quantum mechanics, might be replaced with something that’s a closer approximation of our actual reality. But that won’t invalidate what we already know; it will merely extend it. 

Scientific revolutions aren’t what most people think, but they are going to come, eventually. Here’s what the revolution will actually look like.

Earliest Signal Ever: Scientists Find Relic Neutrinos From 1 Second After The Big Bang

“This cosmic neutrino background (CNB) has been theorized to exist for practically as long as the Big Bang has been around, but has never been directly detected. Because neutrinos have such a tiny cross-section with other particles, we generally need them to be at very high energies in order to see them. The energy imparted to each neutrino leftover from the Big Bang corresponds to only 168 micro-electron-volts (μeV) today, while the neutrinos we can measure have many billions of times as much energy. No proposed experiments are theoretically capable of seeing them.

But there are two ways to see them indirectly: from their effects on the CMB and on the large-scale structure of the Universe.”

When we look at the Universe, one of our great cosmic quests is to go earlier than ever before. To the first galaxies, the first stars, the first atoms, and even earlier, if possible. That’s how we put the best theories of our cosmic origins, like the Big Bang, to the ultimate test. The earliest observable signal from the classical Big Bang is a bath of neutrinos and antineutrinos, which froze-out when the Universe was just 1 second old. For generations, this was regarded as an undetectable prediction, but there are two ways that they might affect observable features of the Universe.

It’s 2019, and we’ve now seen them both. The results? The cosmic neutrino background looks exactly like the Big Bang predicts. Come get the incredible scoop!

The Five Ways The Universe Might End

4.) Dark energy could transition into another form of energy, rejuvenating the Universe. If dark energy doesn’t decay, but instead remains constant or even strengthens, there’s another possibility that arises. This energy, inherent to the fabric of space today, may not remain in that form forever. Instead, it could get converted into matter-and-radiation, similar to what occurred when cosmic inflation ended and the hot Big Bang began.

If dark energy remains constant until that point, it will create a very, very cold and diffuse version of the hot Big Bang, where only neutrinos and photons can self-create. But if dark energy increases in strength, it could lead to an inflation-like state followed by a new, truly hot Big Bang once again. This is the most straightforward way to rejuvenate the Universe, and create a cyclic-like set of parameters, where the Universe gets another chance to behave like ours did.”

Based on the best knowledge and data that we have today, it’s clear that the Universe isn’t just expansion, but the expansion is accelerating. Does this determine the fate of our Universe unambiguously? If we extrapolate what the data indicates about dark energy into the future, we fully expect that structures (like our local group) that are gravitationally bound today will remain so into the future, but that larger-scale structures which are unbound (like our supercluster, Laniakea) will eventually dissociate. But extrapolation is tricky, and assumes that dark energy doesn’t change over time.

If we allow the possibility of change, though, many more possibilities arise. Here are the five most likely, and how we’ll distinguish between them!

Ask Ethan: Are We Deceiving Ourselves By Searching For B-Modes From Inflation?

“I have a question about B-Modes. I’ve read Dr. Keating’s book, Losing the Nobel Prize. In the book, he details his team’s search for B-modes, and claims this would be smoking gun for inflation. Dr. Hossenfelder, in a blog post, says this isn’t true and there are other ways to produce B-modes. What is the correct view?”

Perhaps the greatest danger in science is to go out, look for a predicted effect, find it, and declare victory. Why is that such a danger? Because your idea for how the effect was generated might not be the only possibility, or even the most accurate one. If I have a wild new theory that predicts some far-distant star will have a habitable planet around it, the detection of that planet does not necessarily mean the wild new theory is correct. When it comes to the origin of the Universe, our leading theory is cosmic inflation, which predicts a B-mode polarization signature in the cosmic microwave background. Are there other ways to generate those B-mode signatures, though? And if we find them, does that mean that inflation is correct, or might that be a premature conclusion?

This is a key problem, and a hard problem, in theoretical physics. But we can say a whole lot that’s intelligent on this topic, and still be correct. Let’s find out.