Science is full of surprising discoveries. One that recently won the Nobel Prize in Physics was the discovery that the Universe is not just expanding, but that expansion rate is accelerating. The cause is a mysterious and unexplained ‘dark energy’ which is ever increasing right along with the accelerating Universe. But if the Universe contains all that is and ever will be, where is this extra ‘dark energy’ coming from and is this creation out of nothing a gross violation of the basic laws and principles of physics? If yes, perhaps there’s an even more surprising alternative.
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
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. You 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
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.
No comments:
Post a Comment