What triggered the Big Bang?
Hi, I have a question for you.
What's in your Spotify playlist? One of my favourite songs was written
and played by Dream Theather. It goes like this:
“Where do we come from? Why are we here?
Where do we go when we die?”
While we have no idea how to answer the last two questions, we do know something
about where we come from: the Big Bang. Scientists theorized that we all come
from the same place, even if the term “place” it's ambiguous in this case.
We should say we all come from the same..singularity.
According to the Big Bang model, the matter in your body is billions of years old,
because nothing existed before it, and all that exist come from it. Even us.
But what triggered the Big Bang? Follow me on this video to get to
know more about the Big Bang model and the origin of the Universe.
First, saying that the Big Bang it's a “theory”, could be misleading.
Because of the ones who are not used to a scientific language, the word “theory” recall
something a little far-fetched. Well, this ain't the case.
The word "theory", in the scientific field, does not have the same meaning
as it has in the expression "in theory". In science, the word “theory” means "system
of hypotheses capable of coherently explaining a large number of observations". Theories are
taught because they represent the state of the art of our knowledge on a given set of
phenomena. They are always open to improvement, but they are the best we have at the moment.
If you hear someone saying “It's just a theory”, it doesn't mean anything.
It would be like asking “why do we teach basketball since it's just a set of
movements?”. We teach it precisely because it is a set of movements, to which we attribute
a corporal, social and cultural value. In fact, the Big Bang is the predominant
model in the scientific community based on astronomical evidence and observations.
It is a cosmological model based on the idea that the universe began to expand
at very high speed in a finite time in the past starting from a condition of
extreme curvature, temperature and density, and that this process continues to this day.
According to most astrophysicists, all the matter found in the universe today -- including
the matter in people, plants, animals, the earth, stars, and galaxies -- was
created at the very first moment of time, thought to be about 13 billion years ago.
The universe began, scientists believe, with every speck of its energy jammed into a very tiny point:
everything in the known universe was compressed into a dot smaller than an atom.
This extremely dense point exploded with unimaginable force,
creating matter and propelling it outward to make the billions of galaxies of our
vast universe. Astrophysicists dubbed this titanic explosion “the Big Bang”.
The Big Bang was like no explosion you might witness on earth today. For instance,
a hydrogen bomb explosion, whose centre registers approximately 100 million degrees Celsius,
moves through the air at about 300 meters per second. In contrast, cosmologists believe the
Big Bang flung energy in all directions at the speed of light (300,000,000 meters per second, a
million times faster than the H-bomb) and estimate that the temperature of the entire universe was
1000 trillion degrees Celsius at just a tiny fraction of a second after the
explosion. Even the cores of the hottest stars in today's universe are much cooler than that.
So the Big Bang is the observed truth, but some details haven't been quite worked out.
There are a lot of things that may have happened, and we may need different
explanations to explain those, or maybe we don't have an explanation at all.
In fact, science isn't about being right all the time: it's about being wrong.
If everything was perfectly known, science would lose his intrinsic meaning.
There's another important quality of the Big Bang that makes it unique.
While an explosion of a man-made bomb expands through the air, the Big Bang did not expand
through anything. That's because there was no space to expand through at the beginning of time.
This means that if I and you were sitting on the singularity when it happened,
we would have been incinerated, but we wouldn't have heard any BANG.
But now the point is: every explosion has an
ignition point and a centre of the explosion. What about the Big Bang?
Let's suppose you're on a date and you go out and look at the sky.
Suddenly he/she asks you to point where the Big Bang happened.
Well, my suggestion, in this case, would be to immediately leave!
Because there is no central point, there is nowhere in the sky you can
point and say “that's where the Big Bang was”. Because the Big Bang was everything, and it
happened on the Moon, it happened on the Sun, it happened in your bedroom, it happened everywhere!
Also, at the "peach epoch," the universe was only a tiny fraction of a second old. In fact,
it was even tinier than a tiny fraction — 10^-36 seconds old, or thereabouts.
From there on out, we have a roughly decent picture of how the universe works. Some questions
are still open, of course, but in general, we have at least a vague understanding.
At even earlier times, though, our understanding of the universe gets … fuzzy. The forces,
energies, densities and temperatures become too high, and the knowledge of physics we've cobbled
together over the centuries just isn't up to the task. In the extremely early universe gravity
starts to get very important at small scales, and this is the realm of quantum gravity, the
yet-to-be-solved grand riddle of modern physics. We just flat-out don't have an understanding of
strong gravity at small scales. We. Just. Don't.
Earlier than 10^-36 seconds, we simply don't understand the nature of the universe.
The Big Bang theory is fantastic at describing everything after that, but before it, we're a
bit lost. Get this: At small enough scales, we don't even know if the word "before" even makes
sense! At incredibly tiny scales (and I'm talking tinier than the tiniest thing you could possibly
imagine), the quantum nature of reality rears its ugly head at full strength, rendering our neat,
orderly, friendly spacetime into a broken jungle gym of loops and tangles and rusty spikes. Notions
of intervals in time or space don't really apply at those scales. Who knows what's going on?
The only thing we can do is try to make suppositions.
For example, in a new paper that appeared in November 2019,
researchers detailed the mechanisms that could cause the explosion,
which is key for the models that scientists use to understand the origin of the universe.
In particular, they defined the critical criteria where we can drive a flame to
self-generate its own turbulence, spontaneously accelerate, and transition into detonation.
Actually, they were exploring the supersonic reactions for propulsion, and as a result of
that, they came across this mechanism. The key is applying the right amount of
turbulence and mixing to an unconfined flame until it becomes self-perpetuating, at which
point the flame begins to burn the ingested energy leading to a hypersonic supernova explosion.
There are, of course, some other ideas out there — models that attempt to describe
what "ignited" the Big Bang, but at this stage, they're pure speculation.
If these ideas can provide observational clues — then hooray — we can do science!
But what kind of observations lead to the Big Bang model?
During the 1920s and '30s, Edwin Hubble discovered that the Universe is expanding, with galaxies
moving away from each other at a velocity given by an expression known as Hubble's Law:
v = H*r. Here v represent's the galaxy's recessional velocity, r is its distance
away from Earth, and H is a constant of proportionality called Hubble's constant.
The exact value of the Hubble constant is somewhat uncertain but is generally believed
to be around 70 kilometres per second for every megaparsec in distance, km/sec/Mpc. A megaparsec
is given by 1 Mpc = 3 x 10^6 light-years. This means that a galaxy 1 megaparsec away
will be moving away from us at a speed of about 70 km/sec, while another galaxy 100 megaparsecs
away will be receding at 100 times this speed. So essentially, the Hubble constant sets the rate at
which the Universe is expanding. Since the universe is expanding,
we can intuitively observe that, at a certain point in the past, everything
must have been squeezed into a tiny volume! If we manipulate the Hubble's law, we can see
that the age of the universe can be assessed vis-a-vis the Hubble constant: the inverse
of the Hubble constant has units of time. By substituting in kilometres for Mpc in the
Hubble constant, we find that upon inverting H we get a quantity with units of seconds
(kilometres cancelling out in the denominator and numerator). For a Hubble constant of 100
kilometres per second per Mpc, we get 3 x 10^17 seconds or about 10 billion years.
This is how we determine the age of the universe...more or less!
This is pretty much what we do know about the Big Bang model, and what caused the Big Bang.
Anyway, trying to explain the birth of our Universe is all but simple.
But we have to thank our curiosity that, with a healthy dose of optimism, will lead us to
a deeper understanding of the mechanisms that underlie the birth of the universe.
We would like to end this video with a piece of the lyrics from “The spirit carries on”,
the song we recalled in the intro:
“I may never find all the answers I may never understand why
I may never prove What I know to be true
But I know that I still have to try. “
"This video ends here! Sending love from our team! Are you a fan of the
Big Bang model? Do you think we will ever find out what really caused the Big Bang?
Drop a line below and let us know what you think.