By JOHN PRYTZ
Mysterious Universe: scientists are confident that only 4% of the Universe is made up from normal 'baryonic' matter, the type that interacts with light etc. The other 96% made up of mysterious Dark Matter and Dark Energy.
If you toss a ball into the air, there are two
basic forces at work acting on the ball (ignoring atmospheric friction or drag
of course but one can pretend there's no atmosphere). There's the oomph
(kinetic) energy you give the ball in the upwards direction; there's the
gravitational force that pulls on the ball in the opposite direction. There are
two outcomes.
If you toss a ball up into the air, you expect
just one thing to happen - the ball will go up; the ball will slow down; the
ball will stop; the ball will fall back to the ground. Why? Earth's gravity,
that's why.
If your name is Hercules and you really toss
that ball up into the air, maybe, just maybe, the ball won't fall back down to
the ground. You have given the ball enough oomph energy to overcome, though not
avoid, Earth's gravitational pull. But, even if it doesn't fall back to ground
level, even if it keeps on going up, up and away for all time, it will still be
forever slowing down. Why? Earth's gravity, that's why.
In both scenarios the oomph you give the ball
can never be enough to enable the ball to escape Earth's gravity entirely. The
ball must slow down. That's because the gravitational pull of the Earth on the
ball (and also the ball on the Earth) extends to infinity. At no point does gravity
cut out. You can't escape gravity though your energy oomph can be enough to
prevent its domination - the ball doesn't have to fall back to Earth.
Now, the absolutely one scenario you would never
expect, is that if you toss the ball into the air, even if the ball didn't fall
back down to ground level if it was given really lots and lots of oomph, that
the ball would somehow not only fail to slow down but would in fact speed up.
If you witnessed that you'd suspect that your mind or vision was faulty. The only
way the ball could accelerate away from you is if it had some sort of
additional, internal energy supply (like a rocket). Since it doesn't, it can't.
Now apply that logic to the Universe as a whole.
In the beginning the Big Bang (the explosive event of the creation) gave a
certain finite amount of oomph to all the bits and pieces that make up the
Universe. And thus the Universe is expanding - a standard scenario when you
have an explosion. When a bomb explodes, the result is an expansion of bomb-stuff.
Now all those bits and pieces have a certain finite amount of gravity. The
Universe as a whole therefore has a certain finite amount of gravity.
And so we have a similar contest as per the
ball's oomph and Earth's gravity. Now, either the combined universal gravity of
all those bits and pieces will be enough to overcome the finite amount of oomph
provided by the Big Bang, and the Universe, like the ball, will slow down, stop
and reverse direction (becoming a contracting Universe) or the oomph will prove
greater than all those combined bits and pieces gravity and the Universe will
expand forever, though that expansion rate will slow down over time. The
expansion rate may never reach zero, but the gravity of the bits and pieces
must drag forever and ever on the overall initial oomph. The Universal
expansion will slow down, albeit never to zero. Okay, like the ball and the
Earth, it's pretty much one or the other. You, as per the ball and the Earth,
wouldn't expect the expansion rate of the overall Universe to increase. That
defies logic, everyday experience and basic physics.
For the Universe to accelerate, it would have to
be supplied with extra energy from outside, but the Universe is everything and
contains everything, there is no outside, so where can additional energy come
from? It can't, not without violating one of the most basic of all basic
fundamental physical principles - you can change one form of energy into
another form, but you can't create energy from nothing. Wouldn't it be nice to
just snap your fingers; wave a magic wand, and presto, your empty gas tank is
now full or your cold house is now snug and warm! You don't get something from
nothing! The common phrase is that "there's no such thing as a free
lunch!"
So the fundamental question cosmologists
(astronomers who study the Universe as a whole) were interested in finding out
was whether the Universe's expansion rate was slowing down enough to cause the
Universe to grind to a halt and then reverse; or not. There was never any
question that the expansion rate was slowing down. It was just a question to
what order of magnitude and was it enough to ultimately cause a Big Crunch.
And so it came to pass that two competing teams
of astronomers embarked on a study to crunch the deceleration rate numbers;
answer that question of whether the Universe will eventually cease expanding
and undergo a contraction (like that ball falling back down to Earth) or not
(like the ball that Hercules tossed). Nobody on either team would have bet a
nickel, far less the family farm, that the answer would be none of the above.
Somehow or other, the bits and pieces that make up the Universe gave the middle
finger to gravity. The unthinkable became thinkable, in fact, it became fact.
The Universe's expansion rate was accelerating; therefore energy must be being
created out of nothing to provide that extra gravity-defying oomph; there was
such a thing as a free lunch after all! The mysterious and unknown energy
source behind this unexpected phenomenon was termed 'dark energy'.
There's little to dispute in terms of
observational evidence for the existence of 'dark energy', or rather the fact
that the expansion rate of the Universe is accelerating. Evidence has gone from
strength to strength.
This discovery was so great, and so totally
unexpected, that the team leaders were awarded the Nobel Prize in Physics
(2011) for it. But, it must be pointed out that the recognition was for the
discovery, not for the explanation. There is no explanation. You can't
adequately explain a free lunch! You need extra energy oomph to power up the
acceleration rate of the Universe just like you need an extra surge of gasoline
to accelerate your car. Where does that extra energy come from and keep on
keeping on coming on from? Just calling that addition source 'dark energy'
provides no explanation for the free lunch it is. There is a fundamental
problem here.
How so a free lunch? Well if I have my facts
right, the way 'dark energy' works is this. Dark energy is an intrinsic
property of space that exerts a pressure that causes that space to expand,
which in turn creates new space which has 'dark energy' as an intrinsic
property which results in that space expanding thus creating more space and
thus more 'dark energy' and so on and so on. More space means more 'dark
energy' which means more space, etc. It's creation out of nothing, or, it's a
free lunch. Now this notion of an expanding space alone puts me at odds with
the establishment of modern cosmology. We part company here since I remain
convinced the Universe is expanding through existing space. But that still
leaves the acceleration rate to the expanding Universe, even if through
existing space, as an anomaly.
From the Oxford Companion to Cosmology (2008) we
have this snippet: "The simplest dark energy model is the cosmological
constant*, which maintains a fixed density as the Universe expands... Thus far
the cosmological constant has proven capable of explaining all relevant
observational data, and thus is the chosen ingredient of the standard
cosmological model."
What's wrong with this statement? It postulates
a free lunch, that's what.
Let's drop down a notch in scale and look at
something more familiar.
To illustrate, take a pure ice cube which has a
density slightly less than the pure fresh water from which it came (which is
why ice cubes float in water). Say the ice cube is one inch by one inch by one
inch or one cubic inch in volume. Now double the dimensions to two inches by
two inches by two inches. The ice cube is now eight cubic inches in volume. The
ice cube has expanded in volume -so far so good. The density of the ice cube
hasn't changed, so you have to account for the creation of the extra seven
cubic inches of ice. If you can't account for the additional seven cubic inches
then something is amiss. The alternative is that the original ice cube has
expanded, but no additional ice has been added, so the density of the ice cube
has decreased - same amount of ice but spread over a greater volume. But that's
equally screwy. You can't change the density of ice and still have ice. Density
is a fixed parameter of the substance we call ice.
Now change the ice to water vapour and you can
alter the parameters. One cubic inch of water vapour can expand to eight cubic
inches of water vapour. If you don't add extra water vapour then the density of
your original cubic inch of water vapour obviously decreases in the expansion.
You have less water molecules per unit of volume than you had originally. Now
the Universe is like water vapour. The Universe is not one solid lump like our
ice cube; rather it's zillions of bits and pieces (like water molecules) that
occupy and spread throughout an ever expanding volume. The same amount of stuff
expanded into a greater volume means of necessity less density. Any high school
student knows that.
You cannot have the concept of density without
also talking about the density of a something (like the cosmological constant).
It's meaningless to talk about the density of nothing. That something could be
matter, energy or more likely a mixture of both since it's hard to conceive of
energy-less matter or matter in an energy-less state. In fact it's physically
impossible.
But note the Oxford phrase above: "the
cosmological constant, which maintains a fixed density as the Universe
expands" - something's screwy somewhere.
If we can't accept creation of this mysterious
cosmological constant 'dark energy' out of nothing, whatever is driving the
accelerating expansion of the Universe (call it 'dark energy' if you must) must
also be getting thinner and thinner on the ground, but that would be like
easing your foot off the accelerator pedal of your car. Your car would cease to
accelerate and ease back to a constant velocity (in Universe terms a steady
expansion rate) or a deceleration (which is what our two teams of cosmologists
were trying to measure in the first place). So it's a Catch-22. We can't have
creation out of nothing (a free lunch) - that is just not acceptable - but
without it you can't have an expanding and ever accelerating Universe which has
been experimentally observed.
I used to think that 'dark energy' must be a
variation on the theme of the vacuum energy, but I couldn't figure out how to
get a free lunch out of the vacuum energy. For the perplexed, the vacuum energy
just means that even when you seemingly have nothing, a vacuum, you still have
some energy present. Translated, you can't have an absolute state of
nothingness which would be a theoretical temperature of absolute zero. At the
micro or quantum scale, since energy and mass are equivalent (Einstein's famous
equation), energy can be converted to mass - usually a pair of
matter-antimatter particles, which annihilate each other quick-smart returning
the energy back to the environment that created them in the first place. Mass
can be converted to energy. There's no free lunch. Conservation laws and
principles rule the vacuum energy roost.
Has the Universe always been expanding at an
ever accelerating rate? No. There are two competing forces at work. Gravity, a
pull force, and this 'dark energy', a kind of antigravity or push force. Over
time, so the story goes, the amount of 'dark energy' increases as space
expands. But gravity doesn't increase. The amount of gravity the Universe has
now is the amount the Universe had way back when. At the start gravity was king
of the hill because there wasn't that much space, therefore that much 'dark
energy'. However, with every passing second the amount of 'dark energy'
increased until it finally overran gravity which was standing still or
constant. At that point of intersection the acceleration began in earnest.
Apparently that was some five or so billion years ago. Prior to that, the
Universe was expanding but at a decelerating rate.
There are two related offshoots to this 'dark
energy' puzzlement. One is the Big Bang itself. Now the standard cosmological
model has it that the Big Bang took place in a small space; a very, very, very
small space. In fact the space available was something atomic sized. You
couldn't even see our Universe with the unaided eye a micro-second prior to the
Big Bang Ka-Boom it was that tiny, yet anything and everything that exists
today, existed then in that tiny volume. Now the problem is that when you try
to figure out the state of play with the mass of the Universe (gravity) crushed
down to the size of an atom, (the realm of the quantum), the equations break
down. You have no idea what the state of play was. In a broader context, the
physics of gravity (general relativity) cannot be reconciled with the physics
of the quantum. Thousand have tried over many decades. They were just banging
their heads against a brick wall. To this day, nobody can fit the hand of
gravity into the glove of quantum physics. The way I like to put it is that you
apparently have two different and incompatible sets of physics software running
the cosmos. That's nuts! That too needs an explanation.
The other - well there's an awful lot of
Universe for just little old us, and an awful lot more was created (that
accelerating Universe) in the time it took you to read that. It's like having a
flea housed in Buckingham Palace that's adding additional rooms on at a rapid
rate of knots. For the flea, it's a lot of wasted space. There's an awful lot of
just about empty space between the planets; between the stars; between the
galaxies; between clusters of galaxies, etc. Why do we, and any other extra-terrestrial
life forms that may exist, need with so much empty space and pretty much
worthless real estate, nearly all of which we can't even reach? That's nuts.
That needs an explanation, like maybe most of the Universe is just visual
holographic wallpaper and has no more reality than the images on your bedroom
wallpaper. Is the Universe in fact just a simulation; a virtual reality?
The way to befuddle an artificially (simulated)
intelligent 'life' form is to give it an unsolvable problem like dividing a
number by zero; calculating the square root of a negative number; coming up
with the definitive final value of Pi; or solving an unsolvable paradox like
something that both is and is not at the same time; how many angels can dance
on the head of a pin; or create a spherical cube. The possibilities are
numerous and it's been used many a time in sci-fi plots to demonstrate the
superiority of wetware (brains) over software (silicon chips).
But what if we weren't wetware (any more than
the characters in your dreams are), but in reality software - say a simulated
being - an artificial intelligence being given unsolvable puzzles to solve like
quantum gravity; why is there so much Universe; why are all electrons
identical; why ghosts; and how come crop circles; how can dragons and griffins
be real creatures without any fossil remains; and how can a viable breeding
herd of lake 'monsters' exist in Loch Ness for so long without absolute
verification, along with other anomalies that make no apparent sense, like why
the expansion rate of the Universe is accelerating.
Conclusion: There's no disputing the
observations that the expansion rate of the Universe is accelerating. While
that appears to be wildly improbable, a violation of natural law, that is
creation from nothing - a free lunch in other words - it's not difficult to do
as a simulation. So, do we live in a simulated Universe as virtual beings?
*The cosmological constant was a concept
invented by Einstein. He knew that the Universe should be contracting under its
mutual gravity yet he and nearly everyone else knew (or assumed) that the
Universe was static. So he needed a constant outward pressure (the cosmological
constant) to balance gravity just-so to enable the Universe to be static -
unchanging. So, when Einstein learned, along with the rest of the world later
on down the track that the Universe wasn't static but expanding, he called his ad
hoc cosmological constant mechanism the greatest blunder of his career in
science. However, the concept, though dormant post-Einstein, has never been too
far from the minds of those who could resurrect it in a flash if it served
their purpose, like explaining the accelerating expansion rate.
Science librarian; retired.
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