Have you ever tried to unscramble an
egg? To take a whisk and stir it
backwards through your breakfast and
somehow end up with a perfectly whole
yolk in an egg white. Probably not, as
such a thing would be impossible.
Now, imagine for a moment that you had
never even seen an uncooked egg, but had
only ever seen them scrambled.
Just by looking at that mass of
yellowish mush, do you think you could
envision what it had once been?
We exist in a universe that has been
churned, refined, mixed, and beaten. Our
brightest minds try to piece together
the scramble to figure out what the
universe used to be before that first
whisk. And luckily for us, thanks to
telescopes like the James Web Space
Telescope, we can see the cooking
process in progress, captured in light
emitted from stars millions, if not
billions of years ago. By looking at
ever more distant stars, we are seeing
ever earlier in the process. But the
further we go back, the harder things
are to unscramble. We are finding things
that throw out our expectations and
seemingly don't make sense, leaving us
to wonder what do we really know about
the early universe? How did it form? And
why is what we're seeing not lining up
with our models?
I'm Alex Mccoan and you're watching Astramm. Join with me today in this
supercut about cooking an egg. I mean,
the origins of the universe. We'll look
over scientists effort to answer those
most fundamental questions and examine
some of the strangest evidence that
seemingly contradicts our answers. It
seems universes, much like eggs, are
very difficult to unscramble.
When scientists revealed the James Webb
Space Telescope's first images back in
July 2022,
it was a source of great excitement in
the astronomical community. The
telescope is a 6,500
kg monster with a sunshield whose 14x 21
m dimensions are around the size of a
tennis court. Its mirror for capturing
light is six times larger by area than
Hubble's lens, which allows it to pick
up more photons from further away to
create crisp images. It boasts numerous
cameras and scientific instruments which
allow it to see across the infrared
spectrum. This is a feature that is
vital to its unique mission. That
mission is wide in scope. However, one
of the things scientists were most
excited about was the James Webb Space
Telescope's ability to see the most
distant galaxies possible. It takes time
for light to travel. So, if you can see
an object in the distance, you are
actually seeing it in the past as it was
rather than how it is. In this way, the
James Webb Space Telescope was designed
to see the earliest moments possible,
collecting light emitted by the first
ever stars and galaxies right at the
dawn of the universe.
Here is an image known as Web's first
deep field. This image is taken from an
area so small a single grain of sand
held out at arms length would block it
from your view in the night sky. At this
scale, individual stars are almost
completely absent. Most of what you can
see here are not stars, which would be
too small to detect on their own, but
galaxies.
Here you can see the fish lens effects
being created by gravitational warping
as relatively nearer objects bend light
around them, distorting what lies
beyond. And here we can start to see the
edges of the universe.
In this image is one of the oldest
galaxies we have ever cited. It is so
far away the light from it when it was
born at the beginning of the universe
has only just reached us. Do you see it?
It's admittedly quite small. By
evaluating markers within the light
given off by this tiny red galaxy,
scientists are able to identify how far
it has redshifted and thus how long the
light from it has been traveling by
comparing it to normal visible light
from similar sources. This tiny dot was
found to be 13.1 billion lighty years
away. No wonder scientists were excited.
By piecing together data from galaxies
like this one, we could begin to
investigate what conditions were like
back then and thus how our universe came
to be. But it wasn't like we were going
into this blind. Long before the James
Webb Space Telescope was launched, we
had already started formulating ideas
about the origins of our universe. Let's
start with a question. How old is our
universe?
You have probably heard that modern-day
science believes the universe to be 13.8
billion years old. It seems rather
unfathomable how anyone can come to that
conclusion. But actually the how is not
too difficult to understand. People just
don't generally ask the question. Either
they scoff at it or they accept it as
truth. So how did we come to that
figure? It starts with the fact that we
currently see the universe is expanding
and cooling. Everything is moving away
from everything excluding forces like
gravity keeping things together. The
speed of this expansion is known as the
Hubble constant. And currently the
universe is expanding at a rate of
80,000 km/h per million lightyear. So
the obvious conclusion from an expanding
universe is that matter is becoming
diluted. There's more space in between
things. This led to an observation after
the discovery in the 1920s that our
universe was expanding. A Belgian
cosmologist, Gor Lmetra, theorized that
if the universe was getting larger and
cooler, it used to be smaller and hotter
with all that energy being squeezed into
a smaller and smaller area. The logical
conclusion to this was that if you
rewound the universe back to its very
beginning, all of the universe's energy
would exist in a single point in space.
This singularity would be infinitely hot
and dense which makes sense. It would
then explode outward in a rapid
expansion which would eventually give
rise to all the galaxies we see around
us. Based on that heat and explosive
expansion, this idea is known as the hot
big bang model. So when did this big
bang take place?
Well, to answer that, we do need to
assume a few things about the universe
first. One, the universe is uniformly
dense on the largest scales. This seems
wrong. It's clearly not uniform. There
are superclusters full of densely packed
galaxies and supervoids containing not
much at all. However, like stars in a
galaxy, zoom out far enough and suddenly
everywhere looks the same.
So we assume the universe is
homogeneous. As a result of that, not
only is matter distributed evenly, but
two, we also assume the universe's laws
and properties are the same throughout
in any direction. And three, we assume
the big bang occurred in all locations
everywhere at once. But why do we
believe that last one? The current value
of Hubble's constant implies that the
entire universe is expanding faster than
the speed of light. Meaning there is a
sphere around us that we will not be
able to see beyond. Past this sphere,
galaxies are moving away from us faster
than the speed of light. Meaning light
emitted by them can never reach us.
Everything within this sphere is the
observable universe. A term you've
probably heard before. We can't see or
detect anything beyond the observable
universe. Which is why we don't know if
the universe is infinite or finite. Even
if it is finite, it couldn't have an
edge and would have to loop around
because, well, the universe is just
that, everything that exists, what would
be beyond the edge of the universe
otherwise.
So, where in the night sky do
astronomers look to see where the
universe started?
Well, the answer is everywhere. Because
the universe always has been the whole
universe. It has just changed in size
from being very small to very big. It
doesn't have specific coordinates
because it is an explosion of the
coordinate system itself.
Under the laws of general relativity, if
these three things, uniform
distribution, universal laws of physics,
an expansion that occurs everywhere at
once, are true, then there is a
connection between how old the universe
is, and how it has expanded throughout
its history.
With these assumptions, we can get
distance and brightness measurements
between objects like stars, supernova,
and galaxies. For instance, white dwarf
supernova always appear about the same
brightness. If an observed supernova is
dim compared to what we expect, it is
because it is further away. Finding out
how dim tells us how far away it is and
thus how far back in time we are
looking. We can also look for
fluctuations in the cosmic microwave
background radiation or CMBBR.
This is what shortly after the Big Bang
looked like, albeit in microwaves. You
can see the CNBR anywhere you look into
space, assuming you have a space
telescope that can detect microwaves,
because Earth's atmosphere is really
good at blocking microwave radiation.
380,000 years after the Big Bang, the
entire universe was hot, around 2,000°.
Even though this heat would have emitted
visible light, we can't see it because
the expansion of the universe has
stretched the wavelengths of
electromagnetic radiation by a factor of
1,000. Meaning the photons no longer
arrive at Earth as visible light, but
rather as microwaves.
So, just like seeing those distant
galaxies billions of light years away
using visible light, we can see what the
universe looked like before galaxies
even existed by observing these
microwaves.
This makes this image effectively the
oldest thing we have ever seen.
Fascinatingly, the slight variations in
the image are the precursors to the
filamentary structure of the universe.
We are quite lucky in that there are not
really any bright sources of microwaves
in the universe apart from the cosmic
microwave background radiation. Which
means this view is a relatively
uncontaminated view of the universe
380,000
years after the big bang. Can we see
beyond that? No, not really. Before
that, atoms were just becoming a thing
and light couldn't travel through the
soup of fundamental particles.
But the CNBR is still very useful.
Comparing it to galaxy clusters we see
today, there is a correlation. So we can
examine the CNBR's fluctuations and use
it as a basis to track the universe's
evolution.
Based on the expansion of the universe
today and how it did expand, we now know
the universe is 68% dark energy, 27%
dark matter, and 5% observable matter.
But what is dark matter and dark energy?
We really don't have much of an idea.
However, we can see their effects. Dark
energy is believed to be the driving
force behind the universe's expansion as
the expansion would have slowed down by
now without it. And dark matter is
gravitational force we can't account
for. Galaxies and galaxy clusters in
particular seem to have a lot more mass
than they should, meaning the
gravitational pull is stronger. Dark
matter is what must keep galaxy
filaments together.
We can observe its influence. In fact,
we can even map out its mass
distribution like in this image. But we
don't know what it is. We can't observe
it. But for our current purposes, we
don't need to know what it is, only what
it does to be able to work out the
universe's age. So, we know the current
rate of the universe's expansion or the
Hubble constant. We know how that
redshifts light. We know the composition
of the universe, and we know its
properties. We can see how galaxies have
evolved over time. We look for
fluctuations in the cosmic microwave
background radiation. We can use all of
this together to extrapolate back to the
earliest stages of the Big Bang. Using
three different instruments, all looking
at different aspects of the universe,
all the answers have come back roughly
the same, 13.8 billion years, with an
estimated 99% accuracy.
But there's another method which has
thrown a bit of a spanner in the works.
While our models of the universe
correlated with the evidence to a
satisfying degree, over the last few
decades, we've increasingly realized
there are things out of place, too. Here
is our first example of where what we
think happened in the early universe and
what actually did happen don't quite
line up. What happens when we measure
the age of stars?
Certain types of stars are very
short-lived, going supernova in a matter
of a few million years. Others could
last for trillions of years. Not that
we've seen one that old for obvious
reasons. In fact, following the
evolution of stars, we haven't really
seen any older than about 13.2 billion
years old. But this does mean that long
live stars that formed as matter was
coalescing shortly after the big bang
would certainly still be around today.
The issue came through the discovery of
Methusela. Methusela is a metal pore
star, meaning it is very old and
incredibly rare. And most special of
all, it is only about 200 light years
away from us, which means we can examine
it relatively closely. Based on its
evolution, it is an estimated 14.5
billion years old, give or take about
800 million years. This means it might
have disproved the 13.8 billion figure.
The JWST has also been placing tension
on our assumptions about the age of the
universe, or at least how quickly things
can form within it. In early 2025, WEB
spotted its most distant galaxy yet. MOM
Z14,
which formed a mere 280 million years
after the Big Bang, is thought to have
happened. While this does not contradict
the 13.8 billionyear estimate, it does
introduce a mystery. Scientists did not
believe galaxies could form in that time
frame, especially one so bright and
large as m14.
It should have taken a lot longer.
So, do we really know how old the
universe is? Roughly, it wouldn't be
surprising to see this figure change as
our technology improves and we will have
a lot more data coming in from web in
the future. Although I don't think we'll
see this figure vary by more than 1
billion years in either direction. At
the end of the day, even with these
other factors challenging our
assumptions, the other evidence that
gave us those assumptions in the first
place still exist all have to be
accounted for in our final model of the
early universe. But there are other
challenges spotted by James Webb out at
the furthest edges of the universe. In
fact, when the James Webb Space
Telescope finally saw the edges of the
universe, we knew we had a problem. Once
Web's data started coming in, as it
resolved light emitted from stars 13
billion years ago, what we saw was not a
sparsely populated proto universe where
matter was only just starting to
coalesce into the first tiny
intermittent galaxies here and there.
The early universe was a bustling place.
It had galaxies,
too many of them. They were too bright.
And the black holes we start to spot in
their hearts had grown too big too
quickly.
As I mentioned earlier, it takes time to
cook up a galaxy. Interstellar gas and
dust need time to subtly come together
under gravity until a critical mass is
reached and stars begin to ignite. These
stars live and die and from their
deaths, new stars are formed. This too
takes time. Cosmologists have observed
our universe and based on what they saw
created models for how old our universe
is and how quickly galaxies form. which
is why the James Web Space Telescope
data caused such a crisis. Things were
not as the models predicted.
Fortunately, some of those problems
proved solvable in the months after the
data was released. For example, the
brightness of the galaxies we could see
through web. This brightness implied
that there were far too many stars
present in those galaxies. So many stars
should have taken much longer to form.
And yet there they were, fuzzy red dots
at the edge of Web's resolution.
However, scientists at the University of
Texas studying Web's cosmic evolution
early release survey realized there
could be another explanation for all
that excess light. And
counterintuitively,
that explanation was black holes.
If we work under the assumption that
there were massive black holes in these
galaxies rapidly consuming cosmic gas,
then the intense friction given off by
these hungry leviathans as they ate
created an excess of light in their
accretion discs. This explains why
galaxies overall seemed brighter and
were throwing off our estimates. Once
you add these shining black holes, you
don't need so many stars. The mass of
each problematic galaxy dropped and
everything fell back into line with the
cosmological model. Problem solved.
This reinforced how important black
holes are to our understanding of the
early universe, which was in and of
itself a problem because the black holes
themselves broke our models, too. In
particular, cosmologists struggled with
the thorny question of how they'd come
to be.
For small black holes known as stellar
black holes, there was no issue. Stella
black holes have masses a few to 100
times that of our sun. And we understand
very well how they are formed. They are
the collapsed remnants of a sufficiently
massive star and there would have been
time for such black holes to form in the
early universe. But scientists were
struggling with the super massive black
holes with masses tens of thousands to
billions of times that of our sun which
tend to lurk at the central point of
galaxies and due to something called the
Edington limit. There just shouldn't
have been time for these kinds of black
holes to have formed where and when webb
saw them. And yet there they were and
they were numerous.
Stella black holes can grow as time goes
on, provided you funnel more mass into
them. But how quickly?
In 1920, an English astronomer and
physicist called Arthur Edington
formulated the idea that there was a
limit to how quickly either a star or a
black hole could grow. This was because
photons carry momentum. A tiny amount,
true, but enough to exert a push. This
is what pushes solar sails on certain
hypothetical spaceship designs. That
tiny amount of momentum imparted by
photons. For mass to enter into a star,
it has to push against a constant stream
of photons that are radiating outward.
And at a certain level of brightness,
not even gravity is strong enough to
pull against the flow. This is called
the Edington limit. And stars that brush
against its boundaries, such as Volraier
stars, bright stars at least 20 times
more massive than the sun, emanating
powerful stellar winds, are just the
slightest nudge away from blowing
themselves apart. For black holes, you
might think this would be less of a
problem. Isn't the whole point of black
holes that they don't radiate any light?
But their accretion discs are a
different story. As we discussed
earlier, accretion discs around black
holes can be incredibly bright,
particularly around super massive black
holes, sometimes dwarfing the brightness
of the stars in the galaxy they reside
in. With brightness comes resistance to
gravity, and black holes have to obey
the Edington limit, too.
So even though given enough time and
mass, stellar black holes could
theoretically grow into super massive
black holes, it doesn't seem plausible
that this actually explains all the
super massive black holes we see in the
early universe. simulations have been
run and although it is technically
possible to grow a stellar black hole
into a super massive black hole in that
time frame, it would require those black
holes to be feeding at near the Edington
limit nonstop since their birth, which
just doesn't happen. Black holes in real
life often run out of mass nearby and
need to wait to run into more or for
more to come to them. To further
complicate the matter, we're not
completely sure that super massive black
holes are the grown-up version of
stellar black holes in the first place.
Although it seems like common sense to
assume so, scientists have been confused
at the lack of the intermediate stage of
black holes observable in our universe.
To be frank, they've not cited any, at
least none for sure.
Super massive black holes are common at
the center of galaxies. And there are
thought to be 100 million stellar black
holes in our Milky Way alone based on
the number we've seen. But intermediate
black holes are suspiciously lacking
with only a handful of potential
candidates. You would think we'd see a
lot more.
Struggling for certainty, scientists
began to hypothesize that super massive
black holes were instead born in some
other way. Many cosmologists have been
exploring the idea that because
everything was much closer together in
the early universe, things might have
been dense enough that interstellar dust
itself could conceivably have collapsed
to form a black hole directly, skipping
the star step altogether. If this is
true, and there is some evidence to
support the theory, then perhaps super
massive black holes were once capable of
simply being born that size or near it
right from the offset, even if such a
thing is no longer possible in our more
spread out universe today. But this is
by no means certain. But then a black
hole called LID 568 came onto the scene.
and the pendulum swung the other way
again.
Lid 568 is a very distant black hole
between 12.1 and 12.3 billion lighty
years away. It's so far away from us
that we can't see it at all using
visible light. The expansion of the
universe has redshifted it all into
infrared ranges. But even its infrared
emissions were too dim to be picked up
by heavy hitters like Hubble alone. It
took the Chandra Cosmos Legacy Surveys
combined telescopes and the incredible
resolution of the James Web Space
Telescope to see it at all. Even then,
LID 568's whole galaxy is a little more
than a faint red and compact dot. But
the light emissions from this red dot
are revealing.
X-rays given off by lid 568's accretion
disc reveal that it was actively
consuming matter in its galaxy's heart
in a way that no one expected.
You see, LID 568 crucially appeared to
break the Edington limit. And not just
by a little, it was 40 times over the
accretion speed limit, well on its way
to having its license revoked. How is
this possible?
At the time, multiple explanations were
given. It turns out that breaking the
Edington limit is in fact possible, but
only for short bursts or in sneaky ways.
For example, jets can help you get
around the Edington limit. If all your
photons are being blasted off in a
single concentrated direction, all the
other directions can eat to their
heart's content. with no photon feedback
getting in the way of a good meal. There
are other possibilities. While
Edington's limit says that once the
brightness of the accretion disc becomes
too high, all the black holes food will
be blown away, there is a period of time
before this happens where a greedy black
hole can snatch at the escaping matter
and potentially enter super Edington
territory. like an overeager diner, it
might pay for it later. But for a short
burst, that level of accretion can
occur.
If this is true, it might just explain
how super massive black holes in the
early universe came to exist. And if lid
568 is accreing matter past the Edington
limit, it would prove such a path to
super massive status is possible.
However, there is some doubt on that
point. Now, in a paper published in the
Astrophysical Journal, two researchers
Diong Kim and Yongqin Im revisited the
James Webb data and realized upon closer
scrutiny that dust may have been
obscuring the black hole more than
anticipated. This would have a knock-on
effect on the black hole's Edington
limit mass, as not knowing the true
brightness of the black hole makes it
hard to estimate how much mass it is
eating. Once they applied their new
values to the equations, after looking
at more infrared data, lid 568 started
eating mass at a much more normal rate,
well within the Edington limits
guidelines, which means our mystery
endures. If lid 568 does not break the
Edington limit, then that explanation
cannot be used to account for the super
massive black holes exceptionally rapid
formation. And what of the other strange
things James Webb saw? Where are the
intermediate black holes that stellar
black holes ought to grow into on their
way to becoming super massive? Why are
there so many galaxies in the early
universe more than our models should
allow? Do direct collapse black holes,
ones formed from the cosmic dust itself
with no stellar intervening step, really
exist?
Our models might be on the right track,
but something is missing or incomplete.
And this is not the first time we've
noticed this. Let's explore one final
example. An element we use every day in
medicines, alloys, and most importantly,
the batteries in our phones. One that is
strangely missing from the universe, at
least in the amounts we would expect.
So, here's the big question. Where is
all the lithium?
Let's cover some of the basics about
lithium. Lithium is a relatively simple
element. It's one of the alkaline metals
and for a metal is surprisingly soft,
capable of being cut with just an
ordinary steel knife. You might have
seen it used in science experiments in
school as it reacts quite satisfyingly
when mixed with water producing lithium
hydroxide and hydrogen gas. More
commonly is used in phone batteries,
laptop batteries, and in other
electronic devices due to its high
electrochemical potential. But the
feature of lithium that makes it so
important for our discussion is its
internal structure. It's made with just
three protons in the nucleus, meaning
it's one of only a handful of very
lightweight elements that could be
created in the early moments of the
universe. But it's the expected presence
of lithium in the universe's beginning
that causes our problem with the big
bang model. So, what do we think was
going on back then? How exactly does
lithium prove it's wrong?
The universe's origin is murky to us.
But based on what we know, at the very
moment of the big bang, there would have
been no lithium or any other atom. The
very start of the universe would have
been simply too hot.
After that though, even just 1 second
after the universe begins to expand, the
picture becomes much clearer.
1 second after the universe's expansion
began, the temperature of the universe
dropped down to a mere 10 billion° C,
which is actually only 1,000 times the
temperature at the center of our sun.
This was still hot enough that matter
couldn't form yet. The fundamental force
that holds together the nuclei of atoms
would have been overwhelmed by this
intense energy. So everything would have
existed in the form of radiation
instead. our cosmic background radiation
which we mentioned earlier.
The universe didn't remain as just
radiation for long. Just 99 seconds
later, it would have cooled to 1
billion° C and the strong force would
have kicked in. The universe's first
protons by then had started forming and
began binding with neutrons, creating
hydrogen. and the one proton one neutron
isotope of hydrogen known as dutyium.
Hydrogen and its isotopes or versions of
hydrogen that had the same number of
protons but more or less neutrons were
the most common element in the universe.
But hydrogen wasn't the only one.
Everything was still filled with so much
energy that the hydrogen protons
frequently smashed into each other,
underwent nuclear fusion, and soon
created the larger, more complex element
helium with two protons. Once you run
the equations, in the primeval universe,
matter was nearly 76% hydrogen and
nearly 24% helium. But sometimes, very
rarely, another proton would merge with
the other two and would form isotopes of
lithium, bringing the number of protons
up to three in these atoms. By mass,
this made up only 0.0000 000 0 0
07%
of matter in the early universe. But
here is where the mystery comes in. By
examining the spectroscopic data from
stars or by evaluating that same light
as it passes through clouds of matter,
we can evaluate the distributions of
elements in the universe today. And what
we see roughly matches this prediction.
Our own sun is by mass 71% hydrogen, 27%
helium, and 2% other heavy elements,
which makes sense as the sun would have
had time to undergo more nuclear fusion
in its lifetime, slightly altering the
ratios of these elements. These ratios
are mirrored throughout the universe as
a whole. Another strong proof that the
hot big bang model and our equations are
right and that the universe did evolve
in this way. And yet our predictions
about lithium are wrong.
Although the prediction for the amount
of lithium in the early universe is
really low, the prediction is actually
still too high compared to what we see.
Three times too high. Or to put it
another way, as we study the
spectroscopy of primordial stars, the
further away the star, the earlier in
time the light would have left it. We
don't see anywhere near the amount of
lithium we ought to be seeing if our
prediction was correct. There are
further mysteries surrounding lithium.
Lithium 7 is the isotope that we tend to
see in the early universe. This means
that a lithium atom has three protons
and four neutrons in its nucleus. But
there is another isotope of lithium
known as lithium 6 with one fewer
neutron that is meant to be much less
stable and much less common than its
counterpart. Supposedly making up only
two out of every 100,000 lithium nuclei.
While the amount of lithium in the
universe is too low, the ratio of
lithium 6 to lithium 7 is much too high.
Lithium 6 is a staggering 1,000 times
more prevalent in the early universe
than it should be. So, what does this
mean for the hot big bang model? Is it
really back to the drawing board for our
most trusted theory about the universe's
origins? Not necessarily. Two
possibilities exist. One that involves
rewriting the Big Bang theory as we know
it. But there is another explanation
that might just hold the answer to it
all.
When faced with something like these
mysteries, whether that's Methusela
stars or an overabundance of early
galaxies, super massive black holes, or
lithium, one of two things must be true.
Either our observations are wrong or our
models are wrong. Let's consider each
possibility.
It's difficult to throw out the hot big
bang model completely. Nothing else does
as good a job at explaining the
existence of the cosmic background
radiation or the amounts of hydrogen and
helium that we see in our universe. The
quantities of those elements check out
almost exactly with the hot big bangs
predictions which seems to be too
perfect to be a coincidence. That said,
scientists are becoming less certain
about the model as it stands. Steven
Hawking, who was once one of the leading
advocates of the idea that our universe
began with a singularity, later went off
the idea. In his book, A Brief History
of Time, he stated, "Roger Penrose's and
my work became generally accepted and
nowadays nearly everyone assumes that
the universe started with a big bang
singularity. It is perhaps ironic that
having changed my mind, I am now trying
to convince other physicists that there
was in fact no singularity at the
beginning of the universe. As we shall
see later, it can disappear once quantum
effects are taken into account. Those
quantum effects are too complicated to
go into for this video. And this doesn't
necessarily solve the lithium problem or
the others, even if true. But it does
highlight that the origin of the
universe is an evolving branch of
physics and cosmology where the full
explanation of it has not yet been
found. Perhaps our models will one day
adjust in such a way that the lithium
problem falls away even as the broad
brush strokes of the theory remain in
place, letting the jigsaw piece of the
lithium numbers fit nicely with hydrogen
and helium.
The other option is that there is
something wrong with our observations
and there may well be some grounds to
this as there was with lid 568.
Because of the small amounts of lithium
being discussed, it is quite difficult
to see the exact amounts of it that
exist in the interstellar medium until
you look far back enough. The only way
to probe the interstellar medium's
makeup is to shine a light through it
and then see which lines in your
spectrograph get blocked out. This can
tell scientists what elements might make
up a particular nebula or dust cloud.
But this gets harder and harder to do
the further away the target is.
Eventually, it becomes completely
impossible to get an exact estimate.
Instead, scientists are left looking at
the spectrographs of primordial stars
which are not necessarily representative
of the universe as a whole at that time.
A star is a special case. Something
going on inside there might be altering
the amount of lithium present within,
converting the lithium into something
else while boosting the amount of
lithium 6. Although it's difficult to
guess what that process might be. If our
observations could improve and we could
better measure the amount of lithium in
the early universe as a whole, perhaps
the numbers would come back into line on
their own. Maybe the lithium problem
never existed in the first place.
Ultimately, no answer to how the
universe came to be will ever be
complete until all the available data
matches the theory's predictions,
whether that's lithium or other
problematic elements in the universe.