Fringe Dream of Virtual Particles

Last night I had a vividly strange science fiction dream. Like with most of my dreams, and dreams in general, I guess, it was hard to recall all the details in the morning, and this one was no exception, but in a nutshell, the scene started with me in some science lab, describing the idea of how to effectively make a tiny hole in the universe. It was pretty simple—I was using four Tesla coils, perfectly positioned in the corners of the large square with edges of about a couple of meters long and with two small, battery-sized metal plates positioned in the center of the square. The experiment was that at the precise moment, Tesla coils fired four filaments of thunder, reaching the center point exactly between two metal plates at the same time, initiating a process that in the end created a tiny breach in the universe that I was describing in the dream as a brane between dimensions and within the void between multiverses. Anyway, in the process, one plate goes from metallic through dark and eventually invisible, while the other started immediately to glow and emit light and other sorts of radiation.

I was explaining in my dream that the breach positioned one plate just outside of our universe while the other stood here. Most of the pairs of virtual particles that were popping between two plates all the time out of vacuum are torn apart by the invisible plate, making them real particles from that point and attracting one toward itself, while the second particle is always attracted by the other plate, creating radiation and the glow in the process. Very similar to the Hawking radiation emitting from the event horizon of the black hole. Even though those two plates were positioned very near to each other, after the Tesla coils did the job by breaching the universe, they stayed in different realms from that point, keeping a relatively close distance between them and finding new equilibrium even when the coils were shut down.

Our plate was then taken out of the square center, wrapped in the bigger case, and used as a battery that never drains. Or, to be precise, not until the invisible plate in the system that is always outside of our universe depletes itself by doing its job of separating the particles, but it was explained in the dream to be an extremely slow process that takes centuries, even if the battery is used to generate lots of power, like empowering entire city blocks.

I know, having a geeky or nerdy dream can be weird for most people, but it's not that we can choose what to dream, can we? It is surely a product of my daydreams, so to speak, and definitely an outcome from my daily interests in astrophysics by watching various documentaries and reading articles online. The novel-like storyline was definitely the consequence of all of my science fiction fascination in both movies and books, which I enjoy from time to time as well. In this very case, the background of the entire story from the last night and today's post is all about the most intriguing feature of the universe. The one that might change everything one day. Virtual particles. They are one of those scientific theories that has extraordinary potential for the future. If we find a way to capture and control them. Hopefully not by poking our universe with bolts of lightning. :-)

But seriously, and sci-fi aside, let's see why virtual particles are one of those quantum properties I think we still wait to understand fully. First of all, they are not really virtual per se; they differ from real particles only by their short existence in time. Aside from that, they can have some or even all properties of the real particles, including mass, but so far it is not really possible to observe virtual particles due to their short lives. However, in the subatomic world, virtual particles are often found in diagrams invented by Richard Feynman that revolutionized theoretical physics by their simplicity to explain what was really happening during the quantum events.

For example, take the Feynman diagram above. It shows how two electrons collide. The internal line is a virtual photon, which is in this case a representation of the excitation of the electromagnetic field caused by electrons and their interaction. We can observe both electrons, their velocities, and paths, but we are helpless to spot the virtual particle. In this very case, whether this virtual photon is really a particle, lasting only a tiny fraction of time during collision, which would give it the title of an actual mediator of the force, just like what its counterpart, the real photon, is, or it is used just as a calculation aid, it is not really certain, but in the end any particle, real or virtual, is only a representation of the excitations of the underlying quantum fields. However, even though they are called "virtual" because of their unobservability, and even though we can't see how they "look" and "act," in one experiment we are definitely able to observe what they do. Experiment proposed by Hendrick Casimir in 1948 and confirmed by Steven Lamoreaux in 1996. The experiment is probably responsible for my dream in the first place. The Casimir effect of the virtual particle-powered machine is just by using two metal plates positioned very near each other. But to understand the Casimir effect, we need to understand one simple thing. Timespace itself. I am not kidding. This is mandatory and a requirement for further reading. Easy. ;-)

Well, I am not pretending that I understand what really happens in the universe, but mainstream science of the current date says, and I am trying to paraphrase it, that all that is around us and within us and at any point in time is just one soup of various fields. Like the Higgs field I talked about once earlier on the blog. Or gravitational field. Or in this post's story and this particular case, electromagnetic field. Any field, by definition, is a region in space (and time?) that is affected by some force. At any point in the field. It also means that a field is a region in space that contains energy. Now, an electromagnetic field is not something that can occupy a certain part of space. It is literally everywhere. It is a fundamental field that is actually in the background of the entire universe and not just in places with matter. Everywhere. Even in the vacuum, where nothing tangible exists. Some places contain more energy than others, with a vacuum being a place with the electromagnetic field in its lowest energy state. Not zero. Now, keep with me; it gets interesting—let's compare this field with actual soup that is always boiling.

If you are looking at the surface of the boiling soup, you will see bubbles and fluid filaments all over the surface, but at some places they are heavier and more powerful, and at other places they are calmer and more peaceful, but always boiling and moving. If we were able to glimpse a closer look and magnify the surface to see it on an even smaller scale, we would see that the entire surface is in a chaotic state of constant wibbling, wabbling, wobbling, blooping, and bubbling*. The same is with electromagnetic fields. The stronger wabbles are what we identify as electromagnetic radiation that propagates forward (and in the case of our soup, outside the pot to the kitchen floor), while the tiny wibbles are just a short-lived emission of photons or failed radiation, if you will.

That tiny failed radiation is possible thanks to quantum mechanics that allows temporary violations of conservation of energy, so one smaller particle can become a pair of heavier particles, and in the case of a photon, it goes from changes of being a wave, a mediator particle with no mass, or a pair of heavier particles—a couple of electrons and positrons (or a pair of quarks and antiquarks with radiation of one gluon). What exactly it is and when it happens is dependent on the ongoing process and energy levels of the system, but in the case of the lowest energy state of vacuum, we know that heavier particles are popping all the time, and due to the uncertainty principle, those virtual particles always appear in pairs. They are borrowing the energy from the vacuum and immediately collide and annihilate themselves, repaying the energy in order not to violate the laws of thermodynamics. These streams of virtual particles "coming out of vacuum and diving back" are well-known quantum features known as quantum fluctuations of the electromagnetic field.

Now, those virtual particles popping out into short existence are coming pretty randomly—and in all possible wavelengths—which brings to "the surface" a vast amount of energy due to their short life, normally invisible to us. If we position two uncharged metal plates very near to each other (less than a micrometer), only those virtual particles whose wavelengths fit a whole number of times into the gap emerge between the plates, while outside, without limitations, all possible wavelengths are accounted for. The result is that energy density between the plates is way less than the energy density of the surrounding space, and immediately a tiny force appears and starts pulling the plates toward each other. This force is named the "Casimir force", and the entire system the "Casimir effect". On first glance, it doesn't look strange—the same effect can be made with two plates in water that, with small waves created by a sonic generator**, are pulling toward each other as well—but keep in mind that the actual Casimir experiment is performed in a vacuum with no single atom of matter between or outside the monitoring system, and the plates are uncharged. So the "only effort" we need to make is to put them very near to each other, and they will start moving. The force is tiny, though; for example, for the one-square-meter plates apart by just one micron, the force is 1.3 mN*** (the weight of 1 kg is about 10N). The force is stronger for bigger plates and with shorter distances in between.

However, one potential propulsion engine, built on the principles of the Casimir effect with even a tiny but constant push like this one, is comparable with ion engines that create thrust by accelerating ions with electricity. For example, in "Dawn", the spacecraft that recently arrived in the asteroid belt was propelled by three xenon-ion thrusters, each with a force of only 90 mN. Eventually, after more than 8 years of travel, it accumulated acceleration over the mission to more than 10 km/s (41,260 km/h), which is pretty fast for a tiny push (even though it used other means of acceleration like gravity boost while transiting Mars). It carried almost 400 kg of xenon for the ion thrust engine, but the potential Casimir engine of the future would need none of such a payload. Its propellant would be the very vacuum of spacetime and its pairs of virtual particles.

Of course, the real application would come with separating virtual particles like in my dream or what black holes seem to do**** on a daily basis. If there is a way to make virtual particles real, the millinewtons will instantly lose that 'milli' prefix and be equipped with one more powerful (perhaps 'kilo' or 'mega'), and that will be something extraordinary. Something that in science fiction has a cool acronym. ZPE. Zero Point Energy. Surely, we must find other means to deal with this than by creating tiny black holes to do the job for us, but thankfully, the quantum world is always full of surprises, and perhaps one day we will build a machine that is capable of taking the energy out of a vacuum safely and is small in size, relatively speaking. Perhaps another quantum effect will be helpful for this job, the one that uses interactions between hydrogen electrons and virtual particles called the Lamb shift. But that is a story for another time.

Image refs:
https://www.nasa.gov/mission_pages/dawn/main/index.html
http://www.livescience.com/50119-superconductors-physicists-gravity-particles.html
http://pics-about-space.com/black-hole-hawking-radiation-diagram?p=3

Refs:
http://math.ucr.edu/home/baez/physics/Quantum/virtual_particles.html
* https://www.youtube.com/watch?v=Kn5PMa5xRq4
https://en.wikipedia.org/wiki/Zero-energy_universe
https://briankoberlein.com/2015/03/06/nothing-but-net/
** https://www.youtube.com/watch?v=PS8Lbq2VYIk
https://www.scientificamerican.com/article/are-virtual-particles-rea/
http://physics.stackexchange.com/questions/147096/are-virtual-particles-tool
***http://math.ucr.edu/home/baez/physics/Quantum/casimir.html
https://en.wikipedia.org/wiki/Virtual_particle
****https://en.wikipedia.org/wiki/Hawking_radiation

Gravis Gravity by Gravitons

Don't take this title too seriously. It's wrong on multiple levels. Grammatically and scientifically. Nonetheless, it fits perfectly for this post. As for grammar amiss, I used the Latin root word 'Gravis', which means heavy, and it is actually the perfect adjective for gravity as we perceive it here on Earth. As for the scientific issue, the rest of the title might be all wrong. If we glimpse into the features of the three main natural forces of the universe, it is obvious that they work in more or less the same fashion—they use carriers or elementary particles to mediate the force through the force field. The photon is one of them, and it carries electromagnetism, while strong and weak forces in the nucleus, respectively, are mediated by gluons and W/Z bosons, and they are all confirmed in experiments. Gravitons are supposed to be the same thing as gravitational force, but they are never found and confirmed either directly or consequently. Ever since Einstein, we have had second thoughts about whether or not gravity is acting as a 'normal' force at all or if it is something entirely different.

Think about this: you are located in the spacecraft far in space outside of the big, heavy planets and stars and truly experience microgravity. You start the engine, and your fancy spaceboat starts accelerating with about 10 m/s, and each second increases the speed with 10 m/s more. Actually, the right number is 9.806 m/s per second, which is the measurable 1 g force of the planet Earth. In our thought experiment, a spacecraft that works in a fashion that always uses constant acceleration and half the journey from, i.e., Earth to Mars, pushes with 1g, and the other half turns around and uses backthrust with the same 1 g, could not only provide a normal human environment inside the craft, but it would also be very fast and reach the red planet in just three days*. If you can't imagine how this would be working in real space travel, I will only state the name of one fictional spaceship from the sci-fi literature. Its name is Rocinante**, and it is one great piece of interplanetary Corvette from the amazing franchise "The Expanse".

Well, science fiction aside, the point here is that gravity and acceleration seem to be one thing. The obvious conclusion in this chain of thoughts is that Earth and Rocinante are both capable of creating gravity of one steady g. At least it looks the same from the observer's point of view. However, we know for sure that Earth is round and rotates, and no matter where you are standing, it will pull you toward its center without accelerating anything. It's just enormously big and does something to the very fabric of spacetime itself, which is actually pulling you by invoking some mechanism we don't understand yet. Perhaps by using gravitons—our friendly force carriers from the title? Actually, both particle and string theories predict gravitons as real things. In the former case, it is a massless boson with spin-2, while in one of the string theories, it is sort of a closed string with a low-energy vibrational state. I will not go into further scientific details in both theories, but it is evident that a massless particle or low-energy string is very hard to observe, as it either never or extremely rarely interacts with other particles on subatomic levels. Let's compare it with neutrinos for a moment—an elementary particle with no charge and the tiniest mass we can detect. Their large, super-awesome underground detectors, like the Super-Kamiokande Neutrino Detector in Japan, detect only a handful of neutrino interactions with regular matter over a long period of time. For example, when light from the Big Kaboom from supernova SN1987A reached the Earth, Kamiokande detected the sum of only 19 neutrinos from this super explosion. And to use Carl Sagan terminology, there were billions and billions of neutrinos only from that event. Detection of a single graviton, even if we consider some theories that suggest gravitons with non-zero mass, would be extremely hard.

Ever since Einstein's general theory of relativity, scientists have been struggling to find the best description for gravity. If we are looking at it as a fourth natural fundamental force, compared to the other three, it is the weakest by far; for example, gravity is about 36 orders of magnitude weaker than electromagnetic force, and it probably has a trivial influence on subatomic particles. However, it is cumulative and always attractive and therefore plays the major role in the macroscopic realm, making it possible for planets to orbit their stars, and it is behind the recently experimentally confirmed gravitational waves by the LIGO (Laser Interferometer Gravitational-Wave Observatory) experiment. Einstein himself first noticed the difference in behavior of four fundamental forces and spoke of gravity as not a 'normal' force per se but more as a fictitious (or apparent) force that is observed only as a consequence of the curvature of spacetime caused by the presence of large masses or energy throughout the universe. A very nice example of one apparent force is the Coriolis force, or Coriolis effect. It is observed as a force, but in reality it is just an apparent deflection of an object that is moving in the spherical system, such as Earth, that rotates. Deflection is caused by the fact that the rotating speed of the Earth is faster for a moving object located near the Equator than for one near the pole. In simple words, the system you are moving in is also in its own motion that must be included when you want to calculate the actual path of yours; otherwise, you will never reach your intended target. And in the universe, everything is in motion. Gravity could be just that—an apparent force that is caused by the interaction of large moving masses with the fabric of the universe itself that might be in its own motion as well. Or perhaps gravity could be the outcome of the interactions of mass with the potential energy of that fabric itself. In science fiction and also in the quantum science realm, this is known as zero-point energy, quantum vacuum zero-point energy, or simply vacuum energy. If I understand this correctly, by applying Heisenberg's uncertainty principle (we can only know the position or velocity of a moving particle, but never both), every quantum system to sustain this principle must have minimum non-zero energy. In the case of a vacuum, this is the minimum energy of all fields in the universe, including the necessary Higgs field needed to provide the existence of every mass everywhere in the cosmos in the first place.

In the conclusion of the scientific part of this post, I am hoping that whether the future will confirm gravitons and 'pronounce' gravity as a real fundamental force or we finally find how big masses influence the tiny quantum world of the universe's fundamental ingredients, in the end we will have our answers, which might bring more challenges and questions for future generations. Maybe even ways of mastering it by applying some ingeniously clever engineering of future gravity-related devices and tools. Of course, how exactly the world would be changed with full understanding of gravity and gravity-based appliances; perhaps the best vision is in the science fiction of the amazing futuristic thriller "Influx", written by Daniel Suarez.

I am always eagerly acquiring novels with gravity premises in the background if the plot teaser is interesting enough, so I bought 'Influx' a while ago and stored it in my Kindle's queue for future reading. I was a little busy with my work and reading a couple of other novels, but now I have this regret of why I didn't read it sooner. It was really amazing! Just exactly as comprehensive and entertaining as I was hoping for when I saw the book cover in the first place. The science behind the gravity mirror or deflector invention in the book is perfect and just in the realm of sci-fi plausibility I am always looking for. It was explained perfectly well in both the science behind the invention and also in the workflow of all engineering vehicles, armor, satellites, and other appliances that were built on it. If you add to the main 'gravity' twist all 'regular' sci-fi inventions such as AIs, robots, cold fusion, quantum computers, futuristic weapons, immortality, and other non-sci-fi thriller stuff, please believe me that my additional regret after reading this book was that it had only 500+ pages. I wouldn't mind if Daniel added more stories to it and created a sequel. I read somewhere that FOX is interested in the movie, and hopefully this will see the daylight in the end. It perfectly fits for a motion picture, not just because of the science and story but also because of the potential artistic and visual aspect of gravitational falls in all directions that was extraordinary.

Image refs:
https://www.artstation.com/artist/deningart
http://www.thethoughtarchitects.com/2014/04/14/detecting-neutrinos-neil-degrasse-tyson/
http://www.thedaemon.com/

In-text refs:
* http://www.johndcook.com/blog/2012/08/30/flying-to-mars-in-three-days/
** http://expanse.wikia.com/wiki/Rocinante

Refs:
https://en.wikipedia.org/wiki/Graviton
http://www.japantimes.co.jp/news/2012/01/08/national/science-health/japans-super-k
http://rationalwiki.org/wiki/Zero-point_energy
http://abyss.uoregon.edu/~js/glossary/coriolis_effect.html
https://www.youtube.com/watch?v=i2mec3vgeaI

Science of Life in Solar System

There will come one day in the future. Relatively and astronomically speaking, it might come sooner than we think. It could happen way before we realize that there is no turning back. The day when Mother Earth will simply say, Sorry guys, I have no more energy to sustain this kind of life anymore, and when most of the biodiversity cocoons on Earth will reach the ultimate hazard and start imploding back into themselves. Air and water pollution will help a lot, and not even the planet's regular motions will be able to take us into another interglacial cycle. It is as much inevitable as what we are going to do next. We will take a long look toward the stars and say, "Well, we have to do this sooner or later. It's time to leave the Earth. Time to jump into Christopher Columbus's shoes again. And find the new home."

But we will not get far. There will be no warp drives, "phasers on stun", robots, AIs, or artificial gravity like in sci-fi blockbusters, and there will be no scientific breakthroughs that will bring Moon or Mars gravity to the comfortable number of 1. No, we will be completely helpless in all our efforts to terraform other planets and gas giants' moons. Not at first. Or fast. Or to make large asteroids rotate. Or to initiate Mars' core to fire its lost magnet. Or to make Venus act a little less than hell.

Artificial biodomes of Eden in Cornwall, England^*