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

Streets of Corfu

Long ago I started to experience that one extremely memorable dream. One of those that doesn't fade out with the first morning sunshine. Instead, it was regularly popping to the surface of my mind, making me wonder if these vivid images, haunting me every now and again, were just a product of my imagination or perhaps there was something more hidden beneath. In the dream I wander the narrow streets of an unknown city, one after another, and after a while I stumble to the big square with large monumental buildings decorated with dark reddish bricks with no signs or any familiar markings I can recognize. I was always wondering where all these colorful images originated from and somehow always had that feeling that I am probably missing an important link to fully understand the whole picture.

Recently this final link suddenly appeared, and during our vacation last week I accidentally found my dream site, and all missing pieces finally placed together, forming a memory almost 40 years old. Somehow, subconsciously, I have always known that it wasn't the dream at all and all the streets and buildings were very real and instead represent one of those almost forgotten recollections hidden deeply in my memory banks. What I saw in my night vision was the lost memory of the city of Corfu.

It all happened when I was the age of my son today. I was about 7 years old when my parents chose to spend vacation on the island of Corfu in the northern part of the Ionian Sea, just about 100 km away from the southern cape of the famous heel of the Italian peninsula. While waiting for the ferry in the early morning, we took a walk to the empty streets of Corfu (Greek: Κέρκυρα), the main city named after the island itself, and what was once one small walk under the morning sunshine now is just one almost faded memory for some reason refusing to die and from time to time reminding me of a beautiful site I experienced so long ago.

A couple of days ago, almost four decades after my last encounter with the island, I decided to take my wife and son on the tourist cruise to Corfu. The ship was medium-sized and filled with approximately 300 people of different nationalities and a not-so-small group of Serbian tourists. During the final two years of World War I, the island of Corfu served as a refuge for the Serbian army that retreated there on Allied forces' ships. More than 150,000 soldiers, royal government officials, and civilians established Serbian administration in exile during 1916-1918, while in Serbia under occupation of Austrian and Bulgarian armies, only women, children, and old men stayed. We started browsing the city in the street of Moustoxidou, where next to the French Consular Agency lies the honorary Consulate of Serbia, or simply the Serbian House, the museum completely dedicated to the WWI events that happened on the island and the island of Vido (Greek: Βίδο) across the harbor (first three images above).

The center of the city is a labyrinth of narrow streets, and it requires great orientation skills to remember where you are or where you were in order to find the place of interest. While we waited in front of Sorbonne's office of the French consular building, I got the idea to use the extremely elongated portrait size of the 16:9 aspect ratio of the digital format and start taking photos of small stone alleys. Generally I don't like this format compared to its landscape counterpart just because the image looks too narrow in the vertical direction, but in the case of the streets of Corfu, I could say this is an ideal combination. We didn't have much time until the ship departure time, so I chose the "Scene Selector" feature on my Coolpix camera (which is a somewhat improved automated mode in Nikon's software for digital cameras) and started clicking at the beginning of each street we crossed. After little post-processing (mostly minor changes in brightness, contrast, and sharpness), this blog post is the result. I included on this page 36 images of beautiful small and narrow streets, all taken in the center of Corfu.

When I was 7ish years old, I was a lot smaller, streets were empty, and everything looked large to me. This is probably why I remembered the whole site and its mystical appearance in the early hours. Especially when we stumbled upon big city hall with loud church bells echoing through the streets. Today tourism changed the scenery a lot, and streets are full of various stores, coffee shops, and restaurants. Compared to the 70s, now walking the colorful streets full of people and friendly salesmen brought a familiar environment of other Greek towns. However, the unusual city's topography, with up and downhill streets oriented in all directions, provides Corfu with little authentic feeling and a small glimpse of the old times when civilization was still knocking on the doors of all Greek coastal towns. My wife chose some small, authentic Greek tavern run by an old couple where we experienced even further travel to the past, where traditional Greek hospitality was still not influenced by modern times and Wi-Fi hotspots and where time flowed much slower.

Our free time in Corfu was between 2 and 4 PM, and photographing empty streets or scenery was mission impossible. Still, I managed to find a couple of empty streets and alleys or ones with not too many people inside. These photos (in the above last segments) ended probably the best, showing Corfu's special mixture of Venetian, British, Italian, Greek, and Byzantine architecture that mainly originated in the 18th and 19th centuries.

At the very end of this special photo story, I can only recommend this part of the Balkans highly, along with Parga—a small town where we settled for 10 days in a family villa next to an amazing olive-tree forest. I am sure this part of western Greece hides many more interesting places to visit and photograph. If you add the crystal-clear waters of the Ionian Sea and friendly faces wherever you look, I am sure spending just one vacation on the island is way too little time. I will definitely come here again in the future, and this time I am not going to let new memories fade again to the point of haunting dreams like before. I have to say, though, that when I was walking the same streets again after a long time, I didn't experience the typical déjà vu feeling like I described in the blog post last year. Even though there were some glimpses that looked familiar, too much time passed, and I guess I wasn't able to recognize exact spots and views, probably due to the fact that children and adults experience events and scenery differently, and not just because of different points of view but also because a child's mind is a lot emptier, and they simply don't have much data to compare with, especially if they are experiencing something for the first time. Nevertheless, the whole experience with my lost memory was at least unusually unique, and I doubt I would encounter many more like it.

Streets of Corfu (Full Photo Album):
https://photos.app.goo.gl/TLw83qgV8ZmMe1Gi8

Parga:
https://www.mpj.one/2013/08/parga.html
https://photos.app.goo.gl/vSM1DFFafrfvMxU96

Corfu (Wiki and Web):
https://en.wikipedia.org/wiki/Corfu
http://en.wikipedia.org/wiki/Vido
http://en.wikipedia.org/wiki/Serbian_Campaign_(World_War_I)
http://en.wikipedia.org/wiki/File:Serbs_Corfu1916-1918.jpg
http://www.greeka.com/ionian/corfu/corfu-architecture.htm
http://www.pargagreece.co.uk/