The universe can be defined as anything that is, was or will ever be.
So far as we know, it encompasses everything, and through that as a whole remains the most
mysterious phenomenon we can ever know.
It may even be that we are destined to never have a complete understanding of it, it’s
simply too hard, and the experiments needed to glean more information become impossible
to perform.
We are just too small in the face of the great expanse around us.
But there is hope that at least some of the mysteries of the universe may yet be solved,
so here are ten mystery-filled aspects of the lifetime of the universe that in time,
just maybe, we might answer.
Number 10.
Time Zero.
The Birth of the Universe
We live in a universe that exhibits a number of lines of evidence that point squarely to
the big bang, the start of it all, the commencement of all time, matter, distance, and everything
within the universe.
Throughout, there have been challenges to the big bang model, and new ones continue
to appear but none really hold up in the face of observational evidence ranging from the
discovery of the cosmic microwave background radiation, the afterglow of the big bang,
to the expansion of the universe many decades ago.
Any alternative models must account for this mounting evidence, if not a big bang, then
what created these attributes of our universe?
But the Big Bang is not really a seamless idea either, and the biggest reason for that
is that while you can trace it back to a few hundred million years after the event, it
all becomes opaque and we simply can’t see further back in time than this brick wall.
But we can gather clues in a completely different observational way, that of the particle accelerator.
Megamachine accelerators such as the large hadron collider can give us insights on the
creation of particles that would have been a part of the big bang process so long ago
and allow us to get at least some clues as to what was going on behind the great brick
wall.
What we do know is that the earliest moments of the universe were hot and dense, far more
than anywhere in the galaxy today.
That means a lot of particle collisions and honestly a complete mess of changing energies
and transformations between particle types into other particle types.
Chaos.
It’s hard to make sense out of the ultimate chaos that has ever occurred in our universe,
and that’s the challenge scientists face.
But within this are some of the most fundamental mysteries of all.
What set this whole process off?
Unknown.
From what we can tell, there had to be slightly more matter in the universe than anti-matter,
but there seems to have had to be an imbalance between the two.
What caused that?
When and how did dark matter first appear in the universe?
A total unknown.
And no doubt the more we unravel, if we ever truly unravel all of it, it seems likely that
new mysteries will appear.
Number 9.
10 -36 Seconds.
Inflation
While just why the big bang happened, and what, if anything was before it remain serious
mysteries within cosmology, there are some hints.
As Stephen Hawking once pointed out, pondering what might have happened before the big bang
is pointless because it’s also the beginning point of time as we know it.
We think of everything in terms of causality, one thing leads to the next, giving us a perception
of time moving forward but in reality that’s an inherent property of the universe.
It does not speak to what, if anything, is before it, or outside it.
Naturally this has led to interesting ideas being advanced, not the least of which is
the question of Roger Penrose’s cyclic big bangs, where this is just one iteration of
a perhaps infinite occurrences of big bangs and universes.
Or Neil Turok’s two sided universe, reaching in opposite directions out of the big bang,
one in forward, the other perhaps in reverse.
We may never know the answers to these questions, because they may never be testable but one
aspect of the big bang represents a truly weird mystery.
That of cosmic inflation.
In a nutshell, there appears to have been a time period very very early in the big bang
where the universe expanded at a rate much faster than it does at any other period.
Think of it like this, you can have a bomb sitting in a storage facility.
It has the capacity to explode, but chances are it’s not going to unless the exact conditions
needed for it to detonate are satisfied.
The universe may work this way, it’s expansion can be predicted and a certain rate, which
is accelerating, another mystery, but under special circumstances such as those present
in the very earliest moments of the universe it can behave differently.
There is evidence for this in the uniformity of temperature of the cosmic microwave background
radiation.
For it to be as homogenous as it is, all of it had to be in relative close proximity before
inflation.
But for us to see it as it is today, inflation must have happened.
At the same time though, inflation isn’t settled, and there are other models.
This is really a case where there are simply still too many mysteries cumulatively confounding
attempts at truly understanding inflation, and if it happened at all.
Number 8.
20 Minutes to 100 Million Years.
Matter and the First Stars
All material that we interact with in our lives is ultimately matter.
Barring going to space, and even then you must take some of it with you, we will spend
our entire lives bathed in an atmosphere made up ultimately of atoms.
From our life giving water, H20 to the materials that make up our cellphones it all ultimately
comes down to the members of the periodic table.
And this process of the creation of matter began in the early universe, big bang nucleosynthesis,
and while only the simplest atoms were first synthesized, through the action of stars the
universe became populated with the materials that make up everything, including ourselves.
Within a few millionths of a second, the soup of subatomic particles created in the big
bang formed protons and neutrons as it cooled and expanded.
This was the advent of hydrogen, followed shortly after by a few heavier elements.
Most of this happened only within the first 20 minutes of the life of the universe, before
cooling down too much.
The interesting part of this however is in the abundance of helium that was formed during
this time, it puts serious constraints on just how the big bang could have unfolded,
or we’d have more helium than we do.
Interestingly, abundances measured in pristine areas of the universe line up perfectly with
the big bang model.
And this would have paved the way for the formation of the first stars in the universe,
known as population III stars.
We have yet to directly observe a star like this, you’re looking back to the earliest
days of galaxies, but they very likely existed and their supernovas were responsible for
populating the universe with elements heavier than lithium, hydrogen and helium, creating
the building blocks for eventual planets.
But there are still many questions within the topic of the formation of the first stars,
and again, we have yet to directly see them though there are hints and within this leaves
another open question, just when was it possible for the first planets to form.
Number 7.
10-17 Million Years.The First Epoch of Habitability
If you go with certain models that predict the absolute earliest time it was possible
for stars to form, go supernova and populate at least some areas of the universe with heavier
elements you end up reaching back to a time where the entire universe was at a temperature
that was habitable, regardless of a planet, if such things could exist that early, was
near a star or not.
The Cosmic Background radiation itself during this period was warm enough to allow for liquid
water on most bodies in the universe.
While it’s unlikely for planets to have existed during this period, a mere 10-17 million
years after the big bang, if they did it’s also possible for them to have spawned life
unbelievably early in the history of the universe.
More if certain conditions were present, such as a hydrogen envelope on these exoplanets
or heating through radioactive decay, that initial life might have survived far longer
than the period where the CMB was at the right temperature.
But the chances of such early life still existing are very low.
So that leaves us with a rather odd mystery, was there an earlier epoch of life in the
universe?
And if there was, it’s very unlikely that any indications of it still survive and could
be an unanswered question forever.
Number 6.
900 Million Years.
The Second Epoch of Habitability
Regardless of an earlier epoch of habitability in the universe, we know for a fact there
has been a second.
We are a part of that, with life on earth having arisen over 3.8 billion years ago.
But this later epoch of habitability extends much further back from there.
Currently the oldest known planet in the Milky way, known as the Methuselah or Genesis planet,
comes in at about 12.7 billion years old.
While it’s not earth like, it’s a gas giant about 2 and a half times the mass of
Jupiter, and it orbits a pulsar and white dwarf binary system, it shows that planets
began appearing very early in the history of the universe.
This could mean that earth-like planets may have existed billions of years before Earth
formed, and ostensibly might have hosted life and civilizations that could be many times
older than our own civilization.
This of course leads to one of the greatest mysteries of all, the Fermi Paradox, in that
given the age of the universe and the availability of planets, there should be evidence of alien
civilizations everywhere, near and far.
Yet we see no evidence of that.
So where is everyone?
Number 5.
9.2 Billion Years.
The Age of the Earth
One of the more popular solutions to the Fermi Paradox is that for all the age of the universe,
intelligent life hasn’t really been possible until now due to various factors.
In other words, we are simply early in the game and there are few others out there right
now.
What goes with this is the notion that as the universe ages further, we should see an
intelligence explosion, where an increasing number of technological civilizations arise
and join us.
But that’s just speculative, it may be that we are either so rare, though never likely
to be alone, that we will never contact or verify the existence of alien life.
This opens a whole can of mysteries that we have yet to confront.
Today we expect, perhaps half-heartedly, to detect alien life.
A majority of people believe it’s out there somewhere, and some believe it’s here.
But the proof is lacking.
But say after another 10,000 years, we still have found nothing.
Then we have to confront the mystery of why we’re here, and apparently no one else is.
One instance of intelligence in a universe so vast we can only ever see a small part
of it, the observable universe.
The rest is uselessly disconnected from what one can only presume is the entire point of
its existence.
We are, after all, the universe observing itself.
Number 4.
Distant Future Stars that No One has Seen
One interesting mystery in astrophysic lies in the exercise of envisioning the future
of the universe and what becomes possible only through age.
A question here is if there will someday be entire classes of stars that do not currently
exist in the universe based on what we know of physics and then run stellar physics in
fast forward to see what happens.
The reason this is thought to be possible is that the universe is simply too young for
certain types of stars to come into being.
It’s been this way before, there was a time in the universe’s history where stars like
the sun could’t yet exist due to a lack of raw materials to produce the chemical makeup
they have.
One such theoretical future star is that of the blue dwarf.
As it stands right now, the most common type of star in the universe are the red dwarfs,
tiny reddened cool stars that are set to live for trillions of years, far longer than our
sun.
But when the red dwarfs do begin to reach their ends and have consumed much of their
hydrogen fuel, like other classes of star, they must change.
A star like the sun will simply change it’s equilibrium and become a red giant, but not
so for the red dwarfs.
Rather than expanding, very small red dwarfs, about a quarter the mass of the sun or less,
end up becoming hotter on their surfaces, and become bluer.
At least in a sense.
They won’t actually become blue colored stars, it’s more a matter of the light they
emit, and most extreme of the simulations of these future stars creates a kind of blue-white
former red dwarf.
This only lasts for a time before these stars simply become stellar remnants, white dwarfs,
and then they will go through a long very slow cooling stage to eventually become yet
another hypothetical object, a black dwarf.
Essentially a cinder left over from where a star used to be.
But this whole thing is dependent on our currently models to be correct, and given that we have
a partial understanding of the universe, until one of these objects appears in the universe
it may be a mystery for the entire run of humanity because it’s unlikely we will last
long enough to actually observe and of these hypothetical stars.
Number 3.
The Big Freeze
In the history of cosmology there have been a number of theories about what happens at
the end of the universe, or if it even has an end.
Over time however, a consensus has developed based on observation that one aspect of the
universe that we know exists will come to define what happens in the future.
It’s the expansion of the universe, and observation strongly suggests that it will
continue to expand forever.
This means that the universe overall will continue to cool through it’s process of
expansion until ultimately it becomes impossible for the universe to sustain life.
And the expansion of the universe through the action of dark energy is accelerating.
Eventually the cold and the dark take over, where red shift becomes so stretched that
light from other areas of the universe will be stretched to undetectable wavelengths.
Star formation stops due to a lack of hydrogen needed for them to coalesce.
Eventually, all that are left are the red dwarfs, and then they begin to blink out.
So in this vision of the practical end of the universe, at least as we know, the mystery
is in if anyone out there, ourselves included, could somehow devise ways to survive, or if
advanced science will let them create a new universe to escape to.
And there is also the question of late life in the universe, under these conditions, they
could do very little cosmology under a completely black sky and just before their extinction,
they might realize that they have little understanding of the universe, and what once was will forever
be a mystery to them.
Number 2.
Proton Decay
One of the biggest mysteries in particle physics is the question of whether the proton is truly
stable, or will in the very far future decay.
As best as we can tell, the proton seems to be the very definition of stable.
But in the 1960’s, it was suggested that over immeasurable amounts of time, the proton
might decay into two light subatomic particles, a pion and a positron.
One of the uncertainties here involves thing like quantum tunneling, which may be a mechanism
for the decay to happen, but within a more complete understanding of quantum mechanics
and gravity, it’s anyone’s guess whether the major component of matter itself will
in the very far future begin to dissolve.
This will be a strange time for the universe indeed, where matter as we know is beginning
to disappear leaving in its wake a soup of subatomic particles existing in a very cold
universe forever and the nature of the universe is a big bang, a short age of stars and galaxies,
and an end as an infinity of almost nothing.
Number 1.
Iron Stars and Evaporating Black Holes
One of the last objects in the universe will be the black holes.
Stellar remnants will mostly make their way to supermassive black holes, and much of the
universe will even be devoid of cinders.
But even the black holes themselves aren’t permanent, but will slowly evaporate over
enormous amounts of time through Hawking Radiation.
But, if the proton does not decay, there is one last option for objects in the universe,
iron stars, that may form in the distant far future through quantum tunneling, on the level
of 10 to the 1500ths years.
If these remnants ever exist their fate may well be another round of black holes, which
then will also evaporate, and other than the infinitely existing soup of sub atomic particles
doing not much of anything, the universe will have ended and become a remnant in itself
subject to infinite time.
Thanks for listening!
I am futurist and science fiction author John Michael Godier and be sure to check out my
books at your favorite online book retailer and subscribe to my channels for regular,
in-depth explorations into the interesting, weird and unknown aspects of this amazing
universe in which we live.