Category Archives: Physics

General articles on physics.

How a Physicist redesigned the Ghostbuster’s Proton Pack

It can take a lot of effort to create a world where a film’s audience believes the world they see is (somewhat) real. To help make this possible, writers and directors turn to real-world experts. In the case of the Ghostbusters reboot, they turned to Jefferson Laboratories particle physicist, James Maxwell, to get the science behind their props right. In this article, Maxwell was asked what it was like to work on the Ghostbusters set. Here are some of the things he said.

Jefferson Particle Physicist and Ghostbusters Science Consultant James Maxwell

Jefferson Particle Physicist and Ghostbusters Science Consultant James Maxwell

It was an accident

Initially, he thought his involvement would be minor. In fact, when asked by his colleague, Lindley Winslow, to show some film makers around his lab, he thought it was an indie film project. He was very surprised when it turned out the film-makers were from Sony and were working on Ghostbusters. After the team from Sony had seen Maxwell’s lab, they asked him to help them out with some of their prop designs.

He redesigned the Iconic Ghostbusters Proton Pack

The original Proton Pack used a cyclotron as the particle accelerator. You can see read all about it in a previous article on the science behind the device. Maxwell decided to take the idea, flesh it out, and modernize it. This meant an upgrade from the cyclotron to a synchrotron, a more sophisticated particle accelerator. Essentially, Maxwell broke down how the science would work if one wanted to build a miniature particle accelerator, and this is what we see in the movie.

He got asked other science Questions

Feig and Dippold seem to have been keen on getting the science “right” according to Maxwell. Maxwell said he would often be asked specific questions and whether something would work. This might include the use of certain materials in the Ghostbusters arsenal.

He thinks the Movie is Important


The new Ghostbusters with Proton Packs

Maxwell thinks the movie is important. As a child, the original movies helped sparked his interest in science, and he thinks this movie can do the same of kids today. He says:

So having role-models is very important and I am happy with Paul Feig sticking with the idea to not only have scientists, but female scientists as role models.

Most hated Trailer

This has been the most hated movie trailer of all time! To be fair, there are issues with the trailer itself but, can we really judge a movie by its trailer?

Read the article here to find out more about a perticle physicist’s contributions to the movie Ghostbusters.

Explore the Science behind the Ghostbuster’s Proton Pack

The new Ghostbusters (2016) features a major upgrade to an iconic device: The Proton Pack. In the original movie, the Proton Pack was a portable particle accelerator that emitted a stream of positively-charged protons to ensnare negatively charged spiritual entities. This device was based on one of the earliest particle accelerators: the cyclotron.

Ghostbusters Science Consultant

Jefferson Particle Physicist and Ghostbusters Science Consultant James Maxwell

The Cyclotron

Ghostbusters Cyclotron

Basic model of the Proton Pack showing as cyclotron.

The cyclotron was one of the earliest types of particle accelerators ever developed. Invented by Ernest O. Lawrence in 1932, it works by accelerating charged particles along a spiral path. Inside the cyclotron, a charged particle is injected into the middle of the chamber where it is accelerated between two D-shaped electrodes or “dees.” In the case of the Ghostbusters’ Proton Pack, that charged particle is a positron or positively charged electron. The magnetic field passing through the dees bends the particle’s path, making it travel in a circle, while the electric field between the dees accelerates the particle, giving it a “kick” to make it go faster. When the positron beam has enough energy, it strikes a metal target to release a beam of protons.

The Synchrotron

Ghostbusters Synchrotron Proton Pack

The upgraded Ghostbusters’ Proton Pack features a more advanced particle accelerator: the Proton Pack

The upgraded Proton Pack is based on the synchrotron. Like the synchrotrons that make up many of the modern-day particle accelerators, this allows for higher energy particle streams. The idea behind the upgrade was due to the movie’s science consultant, and Thomas Jefferson National Accelerator Facility particle physicist, James Maxwell.

Crossing the Proton Pack’s Beams

Fighting ghosts on the Ghostbusters

Fighting ghosts on the Ghostbusters

The movie’s writers, Paul Feig and Katie Dippold have put considerable effort into getting the science right. It is definitely worth a look at the science behind the Proton Pack.

Article: The Science of The Ghostbuster’s Proton Pack.

Science of the Space Elevator A Bruntouchables Case

Space Elevator

Brian Finch (Jake McDorman) explains the space elevator to Rebecca Harris (Jennifer Carpenter).

Building an elevator to space is not entirely new–the idea has been proposed as far back as 1895. Russian rocket scientist, Konstantin Tsiolkovsky, first came up with the idea in his manuscript Speculations about Earth and Sky and on Vesta. But why would anyone want to build such a structure? Not only would it extend all the way into space, it will be the tallest structure on the planet. To say there are technical challenges is an understatement.

To put somethings in perspective, Mt. Everest’s height is 8.8 km (5.5 mi) above sea-level, and a Boeing 747 can cruise at an altitude of 12.2 km (7.6 mi). A space elevator is expected to reach an altitude of 35,790 kilometers (22,239 miles), the height of geostationary orbit. Finding the right material to build a space elevator is going to be difficult.

There are many advantages to building a space elevator. The present way of using rockets is very inefficient. Rockets ascent by expelling hot gases at high speeds to leave the Earth’s atmosphere. While travelling at high speeds, the rocket loses kinetic energy to atmospheric drag. If we could lift a payload slowly, it would encounter less drag and lose less kinetic energy as it ascends the Earth’s atmosphere. It costs NASA more than $10,000 per kilogram to send payload into low Earth orbit, altitudes of about 200-2,000 km. A space elevator will do this cheaper, safer, and more efficiently.

Space Elevator

Artist depiction of a space elevator.

In the Limitless episode, “Headquarters!” Brian Finch tracks down one of the criminals on the FBI’s Most Wanted List. The alleged criminal, Lawrence Drake (Isiah Withlock, Jr.), is also the inventor of an inflatable space elevator. So how much of this is science fiction, and how much did the show get right? Read my article on Science vs. Hollywood to find out.

Metamaterials and the Science of Invisibility

Invisibility is just one of the many features of Kiera Cameron‘s (Rachel Nichols) City Protective Services (CPS) uniform. A cloaking device, such as the one used by CPS officers, deflects light around it rendering it invisible. Such a device would be based on metamaterials; an artificial material specifically engineered to have properties not be found in nature.


Prof. Sir John Pendry, the father of metamaterials.

The idea for such a material was first proposed by English physicist, Sir John Pendry in 2006 in a paper published in Science, “Controlling Electromagnetic Fields”. In this paper, Pendry describes how electromagnetic fields can be redirected around an object thereby rendering it invisible.

The way a material affects light is largely determined by its chemical composition. A metamaterial is different because its properties are derived from its physical structure; there are repeating microscopic patterns on the surface. Scientists can engineer this structure to bend light around an object thereby rendering it invisible.

Radar Absorbing Materials

HMS Argus using dazzle camouflage in 1918

HMS Argus using dazzle camouflage in 1918

Becoming invisible has always been an important part of military strategy since the 18th century and the emergence of the long-range rifle. Soldiers would camouflage themselves by either dressing in forest green or field grey. During World War I, troops started to experiment with “dazzle camouflage”.

The striped pattern of the dazzle camouflage is a poor choice to hide something as it draws attention to a person or an object. The pattern does have one advantage–it makes it difficult to estimate an enemy’s range. This concept was soon used on ships as it made it difficult for an observer to know exactly whether the stern or the bow was or whether the ship was moving towards or away from an observer’s position.

Dazzle camouflage continued to be used until World War II but its effectiveness was severely limited with the introduction of radar. The Germans sought to hide their craft with the use of radar-absorbing materials, the earliest of which was used on submarine periscopes and consisted of a layered coating of graphite particles and other semiconducting materials embedded in a rubber matrix. This material was effective at reducing reflections in the 20 cm radar band range used by the Allies.


The Horten Ho’s flying wing design made it the first stealth aircraft.

The Germans went further by incorporating carbon-impregnated plywood in the Horten Ho 229–the first ever pure flying wing powered by jet engines. It was believed that the carbon powder in the glue would shield the aircraft from detection by the British early warning ground-based radar, known as Chain Home.

Carbon is a cheap material with low conductivity. This makes it possible tailor conductivity from synthetic materials made from the element. Conductivity can be very poor (if made from insulated grains of carbon black or soot) or very high (if made from connected chains of graphite). When an electric field encounters a carbon-based absorber, it induces electrical currents in the material which are then dissipated as heat.

Structure Dependent Properties

The hint that a material’s shape and structure at the nanoscale could affect its properties came in the 1990s. The British company, Marconi Materials Technology manufactured a carbon material capable of hiding battleships from radar but had no idea how it worked. They approached John Pendry to find the answer. Pendry discovered the electrical properties that allowed the material to absorb radiation didn’t come from the carbon itself but from the shape of its long thin fibers.

This was a significant discovery. Instead of changing a material’s chemistry to alter its behavior, scientists could alter the internal structure at very fine scales–smaller than a wavelength of light–to get the same effect.

All electromagnetic radiation has two components: a magnetic field and an electric field. As an electromagnetic wave strikes a material the atoms respond like a tiny magnet–its electrons move in a circle in response to the magnetic component and back and forth in response to the electrical component.

Each split-ring is designed to respond to the electromagnetic field in a certain way. When put together in an array with other split-rings, the periodic construction of many of these cells interacts with the electromagnetic wave as if these were homogeneous materials. This is similar to how light interacts with everyday materials, e.g. glass.

Each split-ring is designed to respond to the electromagnetic field in a certain way. When put together in an array with other split-rings, the periodic construction of many of these cells interacts with the electromagnetic wave as if these were homogeneous materials. This is similar to how light interacts with everyday materials, e.g. glass.

We can also create a magnetic field by looping a current around a circle. This magnetic field is more concentrated in the center of the loop than outside. Pendry hypothesized that by creating loops of a non-magnetic material, such as copper, he could create a similar magnetic response typically found in magnetic materials. Scientists would be able to tune how electrons move by tuning the size and shape of these loops. This controls how incoming radiation is bent when it encounters an object.

Pendry wondered how far this new insight could go. Would it be possible to change the magnetic properties of a material by simply changing its fine structure alone and not its chemistry? If so, then a theoretical non-magnetic metamaterial could mimic some of the properties of a magnetic substance like iron.

A split-ring resonator array constructed using copper split-ring resonatorss and wires mounted sheets of fiberglass circuit boards. The copper rings respond to the magnetic component while the mounted wires respond to the electroc field of an EM wave.

A split-ring resonator array constructed using copper split-ring resonatorss and wires mounted sheets of fiberglass circuit boards. The copper rings respond to the magnetic component while the mounted wires respond to the electroc field of an EM wave.

Pendry thought of taking this a step further. By cutting the loops, he created what is known as a magnetic resonator that acts like a switch. This switch would allow him to change a metamaterial’s magnetic properties on command. In so doing, by combining what he learned from Marconi’s radar absorbing material he figured a way to manipulate electromagnetic radiation. This makes invisibility possible for Continuum’s CPS officers.

Bending Light around Objects


An example how an object appears invisible using mirrors.

Invisibility can be considered the supreme form of camouflage as it does not reveal anything about an object to an observer. We can accomplish this using a plane mirror and two parabolic mirrors to reflect light around an object. The object becomes invisible from two sides.

Metamaterials make an object invisible by bending light around it.

Metamaterials make an object invisible by bending light around it. (Image from Pendry et.. al. Science (2006): 1780-1782).

A metamaterials invisibility cloak will work in almost the same way as the parabolic mirrors by steering radiation around an object. The many tiny elements of a metamaterial–the fine scale structures–pick up rays or light from the far side of an observer and relay that ray around the material. When the ray arrives at the side facing the observer, it is re-emitted in the direction it would have taken as if the object was not there at all. Unlike the parabolic mirror trick, a metamaterial cloak will have to do so in all directions. To do this, we need a three-dimensional array of metamaterials

The fishnet metamaterial could one day become the invisibility cloak of the future.

The fishnet metamaterial could one day become the invisibility cloak of the future.

One way of accomplishing this is to create a “fishnet”. In this case the metamaterial is made of alternating sheets of glass and silver containing rectangular holes. This design was developed in 2008 at the University of California Berkeley. As light travels through the fishnet, the alternating layers bend light in unusual ways. The research group at Berkeley hope that this array will eventually be able to guide visible light around an object.

Other uses of Metamaterials

The use of metamaterials extend beyond manipulating the electromagnetic spectrum. It can also be used to create acoustic and tactile cloaks, preventing a user from being heard or felt. The acoustic cloak is made from perforated plastic sheets arranged in a pyramid. When it is placed over an object, sound waves act as if nothing is there, as if there was only a flat surface in their path.

The sound cloak is made of perforated plastic sheets in a periodic pattern.

The sound cloak is made of perforated plastic sheets in a periodic pattern.

The acoustic cloak alters a sound’s path in the same way the invisibility cloak does. Sound doesn’t penetrate into the pyramid but is rerouted in a way to create the impression that noting is there.

While it may one day be possible to completely hide future CPS officers in the visible spectrum and from being detected by sonar, what happens when they bump into something or, per chance, someone bumps into them? Metamaterials can also be designed to create a mechanical cloak.

Metamaterials prevent the object at the bottom from being felt.

Metamaterials prevent the object at the bottom from being felt.

Like the acoustic invisibility cloak, the tactile cloak is made from a periodic polymer array, the properties of which are determined by its special structure. AN object placed under a blanket or layers of foam would still be felt under the blanket. When an object is placed under this “cloak” it redirects stress in such a way that its shape can’t be felt when the cloak is touched.

The CPS Invisibility Suit: Is it possible?

The fishnet design has the advantage that it can handle a wide range of wavelengths; previous designs could only cloak at a specific wavelength.There are some disadvantages, however. It only works on flat surfaces and not the sleek CPS uniform we see Kiera wearing.

There is another limitation to wearing an invisible CPS uniform: an officer won’t be able to see out for the same reason you can’t see in. While the suit is invisible in a certain range of wavelengths–the visible spectrum–it is visible in other areas of the spectrum.

We know that a CPS officer’s cybernetic visual implants allow them to see in other parts of the spectrum, in the infra-red and possibly ultraviolet range. In a previous article, we discuss this ability may be based on graphene contact lens, a hexagonal mesh of carbon atoms. A CPS officer can activate their visual implants to see in other parts of the spectrum when they turn invisible.

We can only imagine what tech is hidden in Kiera’s CPS uniform. Though she has revealed some of her suits abilities to us we can only imagine what more she can do.

Continuum and the Bootstrap Paradox

Continuum’s present timeline seems to be littered with objects from the future. This is hardly surprising considering it is a time travel show. Objects like Kiera’s CMR, the Quantum Time Traveling Device, the drug Retrievanol better known as “Flash” and that other mysterious device whose purpose we are yet to learn all exist in a time when they should not as they have not been created.

Alec Sadler (Erik Knudsen) is arguably the inventor of many of these devices. Or, at least, he will be in the future. If present day Alec “invents” these devices by examining them, can he lay claim to their invention? It really comes down to, did he do the work necessary to bring those ideas to fruition? The answer is more complex than you would think and poses some serious problems in physics. This problem is known as the bootstrap paradox.

The Bootstrap Paradox

"By His Bootstraps" by Robert A. Heinlein was originally published in the October 1941 issue of Astounding Science Fiction under the pen name Anson MacDonald.

“By His Bootstraps” by Robert A. Heinlein was originally published in the October 1941 issue of Astounding Science Fiction under the pen name Anson MacDonald.

The bootstrap paradox is a time travel paradox in which an object or information can exist without ever being created. The object or piece of information is sent back in time where it is retrieved and to become the very object or piece of information that was brought back in the beginning.

One example would be a famous author who goes back in time to give his collected best-selling works to his younger self. His younger self sells those works to a publisher and becomes famous. The now older author then goes back in time to give his manuscript to his younger self.

The term originates from the expression “pulling yourself up by your bootstraps” and was used to describe the time-travel paradox in Robert A. Heinlein’s story “By His Bootstraps”. In Heinlein’s story the protagonist, Bob Wilson, recreates a notebook of translations belonging to his future self. At the end of the story, he wonders who actually compiled the notebook as he prepares to give the book to his younger self in the past.

The young and future best-selling author may feel nothing is wrong with this but to some of us, it seems as if he is cheating. Though it can be argued that the young author, left on his own, will eventually produce the work that he becomes famous for, he has not yet created that work. He is not just claiming ownership for something he never worked on but copying it. This is why it seems like cheating.

Bootstrap Paradox

“I think… the Second Law… of Thermodynamics… says these glasses… should not exist. But… they do, Bones.”

All of the author’s best selling work and Bob Wilson’s notebook of translations have no point of origin because no one has actually created any of it. It all exists in an endless time-loop. As matter and information can not exist without being created, it is paradoxical that it would exist inside the loop.

This becomes even more difficult to consider when we consider physical objects. The Second Law of Thermodynamics states that entropy increases over time meaning that any object brought back ages, will eventually break down and decay. This means that no object will be the same when brought back and can not become the same object in the future.

A time loop also poses a problem with determinism. As every action must occur in exactly the same way each time for the loop to exist. No one can act in a way to do something different. There is no free will in this scenario.

Understanding Continuum’s Bootstrap Paradox

Bootstrap Paradox

Head Frelancer Catherine explains the nature of time in Continuum.

Though it seems that the laws of physics conspires against young Alec to prevent him from taking advantage of his older self’s work and inventions, it doesn’t. At least not in the way we understand the show’s physics. We know at the start of Season Three that time is not immutable. It can change depending on a person’s actions to not only give rise to new branches but to eliminate old ones.

This branching timeline idea means that both objects and information can travel between timelines thus resolving the paradox. In an original timeline, Alec Sadler, played by William B. Davis, was the genius that created the inventions of the late 21st century. All the inventions that Alec creates now have a point of origin or creation. It’s just in another timeline.

When someone travels back in time, they can bring any objects or information with them and create a new timeline. This means that a younger Alec can use information from an alternate future to recreate technology in his own time line without violating any laws of physics. He can, for example, use information from Jason and dead Kiera’s CMR to recreate his medical monitoring wrist band, Halo.

Multiple timeline also solves the problem of determinism. In a loop, everyone must continually do everything that happened before without deviation and with no apparent free will. A new timeline means people’s choices will shape the outcome and events in the future.

Who’s the Original?

Hirsute from A.J. Bond on Vimeo.

In “Minute of Silence”, (Season 3, Episode 9), Carlos Fonnegra (Victor Webster) shows Alec the dead Kiera frozen on ice. “You and me. We’re originals,” he tells Alec. But are they? It’s not surprising that Carlos would make such a statement or even think it. We all like to think we are original or special in some way. In reality, neither he nor this timeline’s Alec are originals. They are just copies.

In A.J. Bond’s time traveling short story, Hirsute, a young time traveler tries in vain to solve the problem of time travel. Deciding that if a solution exists, he will simply go back in time and give himself the answer. To his surprise, nothing happens. No one comes to visit. Maybe time travel is impossible.

The next scene replays exactly as before but this time someone comes back with the answer. Excited to see his older time traveling self, the young physicist claims a victory. Or tries to. His older time traveling self tells him that he did nothing and hasn’t invented time travel. The older and hairless time traveler is the original.

So as much as Carlos would like to believe that he is the original and not some copy, he is wrong. I wonder who is going to break it to him.

The Science of Continuum’s Cybernetic Visual Implants Seeing the Invisible with Night Vision Contact Lens

In the sixth episode of season two, “Second Truths”, we see Kiera go up against the mysterious serial killer known in 2077 as the Ouroboros Killer. Using her knowledge of the case in 2077, Kiera (Rachel Nichols) discovers that there isn’t one but two killers working together. We see Kiera’s cellular memory review/recall or CMR in action and that her cybernetic visual implants allow her to see in low light and the infra-red spectrum

Continuum Night Vision

Cybernetic visual implants allows Kiera to see in low light levels to capture a killer.

We also see a further use of Kiera’s night vision capabilities in the episode “Minute of Silence”. Both Kiera and Carlos (Victor Webster) track a high-tech free running thief who has stolen an invisibility cloak from Hyper Stealth. Though invisible to visible light, Kiera’s CMR picks up the thief’s heat signature and she and Carlos are able to make a quick arrest.

Continuum Night Vision

While the invisibility cloak may bend visible light and make our thief invisible, it doesn’t do the same for infrared.

Night vision isn’t exactly new. It has been used by the military as far back as World War II. Present day night vision devices look like binoculars strapped onto a soldier’s helmet; not like Kiera’s cybernetic visual implants which have been neatly implanted onto her eyes. A device like this may not be that far off in the future. Engineers from the University of Michigan have built and tested a broadband photodetector using graphene, a honeycomb lattice of carbon atoms that is just one atom thick. Their findings was published in 2014 in the prestigious journal Nature Nanotechnology. The study’s authors hope this will one day lead to night vision contact lens.

The Science of Night Vision

Night Vision

Spectrum showing the visible portion of light. This accounts for a very small portion of the entire spectrum.

It should come as no surprise that many animals have better night vision than humans do. They can either see a much wider range of the light spectrum or see at much lower light levels than we do. Humans, instead, use technology to improve upon what nature hasn’t given us. This works in one of two ways: either by image enhancement or by thermal imaging.

In image enhancement, low light levels, that are imperceptible to our eyes, are amplified to a point where we can observe an image. In thermal imaging, the infrared part of the spectrum is captured with an infrared detector and converted into visible light to produce an image.

The Miracle of Graphene

Night Vision

Graphene is an atomic-scale monolayer honeycomb lattice made of carbon atoms.

A futuristic science fiction device could be based on nanotechnology and made using graphene, a sheet of carbon that is just one atom thick. The carbon atoms form strong covalent bonds and are arranged in a hexagonal shape. This gives graphene unparalleled strength not seen in most materials; its breaking strength is over 100 times greater than a hypothetical steel film of the same thickness.

Night Vision

A lump of graphite, a graphene transistor and a tape dispenser. Donated to the Nobel Museum in Stockholm by Andre Geim and Konstantin Novoselov in 2010.

The material was discovered in 2004 by two University of Manchester physicists, Andre Geim and Kostya Novoselov. The two scientist pulled tiny bits of graphene from a lump of graphite, the same material found in a “lead” pencil, by sandwiching a graphite flake between some Scotch Tape. The tape layers was pulled apart to separate the atomic layers. They continued this process several times until a single atomic layer was left on the Scotch Tape.

Photograph of graphene in transmitted light. This one-atom-thick crystal can be seen with the naked eye because it absorbs approximately 2.3% of white light.

Photograph of graphene in transmitted light. This one-atom-thick crystal can be seen with the naked eye because it absorbs approximately 2.3% of white light.

What may come as a surprise to the average non-scientist is that no special equipment is needed to view this single atomic layer of carbon atoms. Graphene is considerable opaque considering it’s only one atom thick. The layer absorbs 2.3% of the light incident on it making it very easy to see with the naked eye.

If this 2.3% doesn’t sound impressive, that is because it really isn’t. Compared to a material like silicon, which is used to make solar cells, it doesn’t absorb as many photons. However, it does have one advantage over silicon–it has no band gap.

Night Vision

The bandgap for insulators, semiconductors and conductors.

Band gaps exist in both insulators and semiconductors and is the energy needed to get electrons flowing in either material. Metals conduct easily because their valence and conduction bands overlap and require no additional energy to get them moving. Semiconductors can get this energy from light. If a photon with enough energy strikes the surface of a semiconductor, it knocks and electron loose and the material starts conducting. If there isn’t enough then it remains an insulator.

If a photon has more energy than the required amount, then the extra energy is lost unless it has twice the energy of the band gap. In this case the photon will liberate two electrons. This is the reason why, under ideal conditions, the silicon based solar cells maximum efficiency is about 30%; they can only absorb photons with energy in a tiny range. Graphene has, what is known as, a zero band gap which means they can absorb photons of all energies. So while it doesn’t absorb as many photons as silicon, it makes better use of the much wider range of photons that it does absorb. This is of considerable interest to scientists as they could become highly efficient solar cells.

Kiera’s Cybernetic Visual Implants

Kiera Cameron's Cellular Memory Review being installed during her first day as a Protector for the City Protective Services.

Kiera Cameron’s Cellular Memory Review being installed during her first day as a Protector for the City Protective Services.

Kiera’s cybernetic visual implants form part of her CMR or cellular memory review. The CMR is based on a liquid chip technology that interfaces with the visual implants to give users a Heads-Up Display. The visual implants also allow its users to see beyond the visual range, to detect infra-red radiation and see in low light conditions.

Present day night vision devices are clunky. Devices that can see in the low-IR region typically requires detectors to be cryogenically cooled to reduce their atom’s thermal vibrations as much as possible. Neither of these characteristics are ideal for the future of law enforcement. Future City Protective Services’ (CPS) Protectors will need to carry liquid-nitrogen cryogenic backpacks for their visual implants to work effectively.

Graphene may solve this problem as it is also able to absorb infra-red photons at room temperature. The problem is that it doesn’t absorb a whole lot of infra-red photons. Its sensitivity is about one hundred to one thousand times lower than any commercial device on the market; any signal it produces will be too weak to produce an image. Researchers at the University of Michigan, led by Zhaohui Zhong, have found a way to capture and amplify the signal into a device smaller than a pinky nail.

Night Vision

An insulating layer is sandwiched between two sheets of graphene to create an optical transistor.

The IR detector is created by sandwiching an insulating layer between two sheets of graphene. A tiny electrical current runs through the bottom sheet. Electrons are released as infrared photons strike the top graphene layer. These free electrons quantum tunnel through the insulating layer where changes in current flow in the bottom layer is measured and observed. Zhong and his team were able to use this to determine the brightness of light striking the upper layer and create a viable method of detecting infra-red radiation in something that could, one day, fit inside a contact lens.

We have seen Kiera monitor physiological function and identify chemicals using her CMR. This graphene-based device could also, one day, go beyond military and law-enforcement applications to use IR-wavelengths to monitor blood flow as well as identify chemicals from their heat signature. Could the tech we see on Continuum become a part of wearable electronics that will expand our vision and provide us with another way to work and interact with our environment?

The Science of Godzilla’s Roar Does he really purr like a cat


There is nothing as intimidating or awe-inspiring as the most famous Kaiju’s roar. Though fictional, this is one of the things that defines him other than his massive size. But there are problems were physics is concerned. Sound is generated by the larynx in one of two ways: either purring mode or flow-driven mode. Purring mode depends on how quickly the vocal folds or vocal cords contract and vibrate. Flow-driven mode depends on how passing air vibrates those folds.

The sound produced in flow-driven mode depends on the size of the larynx. The larger the larynx, and hence the vocal folds, the lower the sound. Godzilla is so large, his roar would be in the infrasonic range; below the range of human hearing. Purring mode suffers from no such limitation. Could the King of Monsters actually be purring? Read my MoviePilot article to learn more.

Continuum, Time Travel and The Grandfather Paradox

The last episode to Continuum’s second season (“Second Time”) sees a grief stricken Alec Sadler (Erik Knudsen use the time travel device to go back in time to save the life of Emily (Magda Apanowicz). A shocked and distraught Keira (Rachel Nichols) looks on as Alec disappears from the time line in a flash of light. What is everyone’s favorite Protector to do now that the time travel device no longer exists? Is she forever trapped in the present unable to do anything about Alec’s betrayal?

If you were hoping to find out what Kiera would do now that she is stuck in the present then don’t hold your breath. Alec reemerges in the past–one week in the past to be exact–to create a new timeline while Kiera is captured by the Freelancers. The original timeline, as explained by Head Freelancer Catherine (Rachael Crawford) no longer exists. The intense roller-coaster ride and the jaw-dropping events of the last season, from the pinning of Agent Gardiner’s (Nicholas Lea) murder on Kiera to Carlos Fonnegra (Victor Webster) leaving the Vancouver Police Department to join Julian (Richard Harmon) and Liber8 never happened.

So what are Continuum fans to do? Are we simply to ignore the last episodes of Season Two as if they never happened? That remains an open question.
The Season Three premier certainly continues with the same action packed intensity from which the last season ended but it does something else–it explains the time travel rules upon which the show is based. It also appears that the show’s writers have put a lot of thought and effort into ensuring that these rules are as consistent as possible, especially where the issues of paradoxes are concerned.

The Paradoxes of Time Lines

Continuum Time Travel

Head Freelancer Catherine explains that time travel is not immutable and is like a brancing tree that needs to be pruned.

“Destiny is not set. Time is not immutable. The continuum is like a tree. It can grow wild or it can be cultivated.”

In the premier episode, head Freelancer Catherine explains the concept of timelines and the physics of time travel to Kiera. While there is only one timeline, it can be changed. Go back far enough in time and you can change everything to create an entirely new and different timeline.

This answers some of the paradoxial questions of the last two seasons, if Maddie (Olivia Ryan-Stern) was really Kellog’s (Stephen Lobo) grandmother, then why didn’t he pop out of existence in the current timeline. One idea put forward by Alec was that she may not have been Matthew’s grandmother. It turns out she could have been and to understand why, we must look into how Continuum’s physics of time travel resolves the Grandfather Paradox.

The Grandfather Paradox

The grandfather paradox is one of the more well-known time travel paradoxes and was first described by the science fiction writer René Barjavel in his 1943 book “Le Voyageur Imprudent(Future Times Three). In this scenario, our time traveler goes back in time before his grandfather is married and kills him. The paradox is that the time traveler is never born and can not go back in time to kill his grandfather. His grandfather is free to meet the grandmother, get married, have kids and our time traveler is eventually born. When the time traveler gets older, he steps into his time-machine and goes back in time to kill his grandfather. This cycle continues ad infinitum and without resolution.

Recognizing this vulnerability, in the Season One episode “A Test of Time”, Kagame (Tony Amendola) decides to test this paradox and possibly get rid of their “Protector problem” once and for all. Liber8 start by killing young women with Kiera’s grandmother’s name–“Lily Jones”. During the course of the episode Liber8 take additional insurance by planning to kill Kellog’s grandmother; revenge against Kellog for helping Kiera. Travis (Roger Cross) shoots Kellog’s grandmother and everyone sees that Kellog does not disappear–the grandfather paradox does not apply to them. Or does it?

According to Catherine’s explanation of time travel, killing Maddie creates a new time line. In this new timeline Kellog will not be born and many of the events in Kellog’s life, from his meeting Kiera to his part in Liber8 will never happen. In a sense the very timeline that Kiera so desperately tries to protect no longer exists but this doesn’t mean that Kellog’s absence changes things so completely that the future Kiera and the Freelancers are trying to protect never happens. Kiera’s primary concern is her family but everything can still go according to plan even though Kellog no longer exists in the new timeline.

Catherine and the Freelancers appear to subscribe to the Great Man Theory, a 19th-century idea in which history can be explained by the impact of “great men”, or heroes. As Kellog is not one of these supposed “great men” then many key events, such as Alec’s rise to power and discovery of time travel, will still happen. This means that Kiera’s family will still exist in the future. As they don’t know who Kellog is, they will also be completely unchanged by the ripple effect of Maddie’s death. The reason Catherine and the Freelancers aren’t too concerned of Maddie’s death is because her impact on the future is negligible–her life or death changes nothing. Talk about a major blow to one’s ego.

Resolving the Grandfather Paradox

Continuum’s time-travel physics provides a logically consistent way to resolve the Grandfather Paradox. A time traveler who kills his own ancestor or whose ancestor is murdered won’t vanish from existence. Rather, the timeline he came from will disappear to be replaced by a new timeline in which he will never be born. As our time traveler is a refugee from the previous timeline that no longer exists, he won’t pop out of existence and is safe from the ramifications of the Grandfather Paradox.

This single and mutable timeline idea not only overcomes the logical paradox and inconsistencies of the Grandfather Paradox but others as well , such as the Bootstrap and Predestination Paradoxes–something we will examine in future blog posts. It also highlights how dangerous time travel is in the series. As time is not immutable, a nefarious time traveler can use a time machine as a weapon to mold the future to achieve for personal gain. Jason has hinted that the Freelancers have meddled with humanity’s history before. The extent of this meddling remains to be seen.

The Freelancers have the power to monitor the continuum and stop people from making these changes to the timeline but this doesn’t mean they are the good guys. Catherine has admitted they see themselves as guardians to the continuum, in essence, the ones who “prune” the tree. This makes you wonder whose interests they represent and whether those interests are the best for everyone. This is interesting because the series has yet to really identify who the good guys and bad guys really are.

While we may at times root for Kiera, as the series progresses we may discover we never should have. We have two Alecs in this timeline. In the last timeline we have seen hints that Alec could be turning to the “dark side” and become the man to usher in a totalitarian and dystopian future of 2077. All that may have been changed with Emily’s death. It is amazing the difference a week makes. Could we see Alec Sadler fight on both sides of this temporal war? Your guess is as good as mine.

The Discovery of the Higgs Boson: Week 2 Review Light Bulbs and Railroad Schedules

The second week of the FutureLearn course “The Discovery of the Higgs Boson” looks at physics of the 20th century–special relativity and quantum mechanics. These two branches of physics represented a fundamental shift in the way we view the world.

It may come as a surprise to some that these deep philosophical shifts have very unexpected origins. Our view of a quantized world came from the need to create a more efficient light bulb while the connection between space and time came from our need to run a more efficient railroad network and international time conventions.

Need for a more efficient light-bulb

Philipp Lenard

Hungarian physicist Philipp Lenard, discoverer of the photoelectric effect in 1902.

In 1902, Hungarian physicist, Philipp Lenard, winner of the 1905 Nobel Prize in Physics for cathode rays, observed that the energy of individual emitted electrons increased with light frequency–the photoelectric effect. This appeared to be at odds with Maxwell’s theory of electromagnetism which predicted that an electron’s kinetic energy should be proportional to light intensity. In 1905, Albert Einstein published a paper that explained the experimental data from the photoelectric effect. Based on Max Plank’s theory of black body radiation Einstein postulated that light energy was being carried in discreet quantized packets.

In 1894, German theoretical physicist Max Planck was commissioned by the German Bureau of Standards with the task of creating more efficient light-bulbs. To do so, Planck needed to find one that would emit as much visible light as possible with very little to no infra-red and untra-violet light. Planck knew from experiments at when an object is heated, it emits radiation in the form of black-body radiation. Planck turned his attention to this problem.

Black Body Radiation

Black body curves for various temperatures and comparison with classical theory of Rayleigh-Jeans. As the temperature decreases, the peak of the black-body radiation curve moves to lower intensities and longer wavelengths.

“Blackbody radiation” or “cavity radiation” is the characteristic radiation that a body emits when heated. This is seen in the form of a curve which peaks at a characteristic temperature where most of the radiation is emitted. Experiments showed that as the temperature changes, so too does the emitted radiation. When the wave picture of light was applied to this problem, it failed to predict the observed intensity for any given temperature.

Planck made several attempts to understand this problem. His first proposed solution in 1899 based on the entropy of an ideal oscillator, in what he called the “principle of elementary disorder”, failed to predict experimental observations. Planck revised his approach in 1900 using Boltzmann statistics to gain a more fundamental understanding of black-body radiation. This approach worked but Planck held an aversion towards statistical mechanics. He was also deeply suspicious of the philosophical and physical implications of its interpretation. His recourse was, as he later put it, “an act of despair… I was ready to sacrifice any of my previous convictions about physics.”

The central assumption behind his third attempt was the hypothesis, now known as the Planck postulate, that electromagnetic energy could only be emitted in quantized form. Planck didn’t think much of this method, regarding it as a mere trick. We know now that assumption is regarded as the birth of quantum mechanics. Try as he might, Planck struggled to grasp the meaning of energy quanta, going so far as to reject Einstein’s hypothesis and explanation of Lenard’s photoelectric effect. He was unwilling to completely discard Maxwell’s theory of electrodynamics.

Not everyone was convinced by Einstein’s hypothesis either, even after it was experimentally verified by Robert Millikan in 1914. Many physicists were reluctant to believe that electromagnetic radiation could be particulate in nature. Instead, it was believed that the observed energy quantization was the result of some constraint of matter and the way that it absorbs and emits radiation. It wasn’t until Compton’s experiments showed that light cannot be purely be explained as a wave that the idea of light quanta was accepted.

Train Schedules and Time Zones

The first passenger carriage in Europe, 1830, George Stephenson´s steam locomotive, Liverpool and Manchester Railway

The first passenger carriage in Europe, 1830, George Stephenson´s steam locomotive, Liverpool and Manchester Railway

The mid to late-19th century saw considerable and rapid improvements in transportation, communication and technology. One of these inventions, the steam locomotive, not only changed the way goods and people traveled but also the way we view time. Products could be moved more cheaply and much faster.

Before the invention of clocks, people marked the time of the day with apparent solar time or by noting the sun’s position in the sky. Local time was different for each town and settlement. With the invention of well regulated mechanical clocks, cities used local mean solar time. As clocks differed between towns by an amount corresponding to the difference in geographic longitude–a variation of four minutes for every degree of longitude–communication between towns and rail transport became awkward. The time difference between Bristol and London, for example, a difference of 2°35′ longitude, is about 10 minutes while the difference between New York and Boston is about two degrees or 8 minutes.

25-0621E.6LTime keeping on American railroads was even more confusing. Each railroad had their own standard of time time, usually based on the local time of its headquarters or main terminus. Each railroad schedule was published using the company’s own time and stations had a clock for each railroad, each showing a different time.

Non-uniform time zones weren’t just confusing. It was dangerous. The incidents of accidents and near-misses became more frequent as more people started using trains for travel. What was needed was a means to know exactly where trains were at all times. The use of time zones solves this problem and with it came the need to synchronize clocks at a distance.

It’s not surprising that many of Einstein’s though experiments concerns trains. As a young patent clerk, many of the inventions he reviewed focused on using light signals to synchronize clocks. Einstein took it a step further and realized that clocks moving with respect to each other would not tick at the same rate.

Physics students are familiar with Einstien’s Gedankenexperiments and that the power of abstract thought can allow one to fully visualize the consequences of an experiment without having to actually perform said experiment. Far from being esoteric examples, Einstein’s thought experiments are firmly grounded in reality and shares its origins in something as simple as a train schedule.

The Higgs Boson Course

In one of the course’s lectures, Peter Higgs says that when he teaches undergraduates special relativity, he ignores the way that Einstein did it and asks, “how do you realize the principle of relativity, which was what was formulated by Henri Poincare?” To do this, you have to abandon Newton’s assumption of absolute time. Peter Higgs is correct, the development of special relativity need not have had anything to do with the Michelson-Morley experiment. In Einstein’s case, it came about from the practical need to synchronize clocks.

The second week of the course builds on the previous week. Though the concepts are quite literally mind-blowing, the ideas and mathematics were conveyed in a way that makes it easy for students to grasp. The third week looks even more exciting as we combine both special relativity and quantum mechanics to make much deeper predictions about our world.

The Discovery of the Higgs Boson: Week 1 Review Conservation Laws and Physical Revolutions

Peter Higgs 2The Higgs boson has captured the world’s attention from the moment it was announced the Large Hardron Collider was being built to find it. The elementary particle’s discovery was announced by CERN on 4 July 2012 and is nothing short of monumental as it appears to confirm the existence of the Higgs field. This pervasive field is pivotal to understanding why some fundamental particles have mass. As interesting and exciting as this discovery may be, its consequences and implications remain out of reach for the general public. Future Learn, a privately company owned by Open University, along with the University of Edinburgh have started a seven week Massive Open Online Course (MOOC) “The Discovery of the Higgs Boson” to introduce the theoretical tools needed to appreciate this discovery.

The course starts with classical mechanics. While it may seem like a strange place to start, especially given the course’s goals, it is a good one. Rather than jumping straight into Quantum Mechanics, classical mechanics makes the mathematics is accessible to students, especially those who have completed A-Level Mathematics or done Calculus. The course doesn’t assume many of the fundamental conservation laws in physics are true but rather goes through the mathematically rigorous process of proving these concepts to students. This also allows students to see how the behavior of physical systems can be deduced. Though some of the physical principles will need to be revised as the course progresses, the mathematical tools students would have acquired remain the same. Student can thus build on what they have learned before.

An Evolutionary Revolution

One of the more interesting questions asked was, “Why is the Higgs boson discovery important?” Dr. Victoria Martin, a reader in particle physics at the University of Edinburgh, answers that in one of the course’s modules. In her video, she says the Sun is a massive burning ball of hydrogen and helium and it is a mystery why it all hasn’t burned up by now. She says the answer comes from Peter Higgs’ theory which predicts the Higgs boson. It predicts why the nuclear process in the Sun is slow enough that the Sun is still around after 4.6 billion years and provides just the right amount of light and heat to sustain life on Earth.

Science didn’t always believe that the Sun or the Earth, for that matter, was old. In the mid-nineteenth century, both Charles Darwin and Alfred Russel Wallace were making the case for biological evolution by natural selection. This theory described a process of slow, gradual changes over time and indicated the Earth had to be very old, at least hundreds of millions of years. This was supported by geologist observations of erosion rates.

Lord Kelvin

Photograph of William Thomson, Lord Kelvin.

This posed a problem for the most prominent theoretical physicist of the time, William Thomson, 1st Baron Kelvin, who saw evidence that disagreed with Darwin. This guiding light of the Industrial Revolution, whose work in thermodynamics contributed to the steam engine, was a devout Christian who believed in a much younger Earth and with good reason. In 1862, using the thermodynamics of heat conduction, Thomson initial calculations showed that it would take between 20-400 million years for a molten Earth to completely solidify and cool.

This large uncertainty of the Earth’s age were due to uncertainties about the melting temperature of rock. This did not deter Thomson who then set out to calculate the Sun’s age in 1868 using what he knew of the Sun’s energy output. Kelvin rightly assumed the Sun formed from a giant gas cloud and gravity eventually caused the cloud to collapse into a ball. As with any falling mass, the cloud molecules’ potential energy would be converted into kinetic energy. This raise in kinetic energy would turn into heat, raising temperatures to result in star formation in a process known today as the Kelvin-Helmholtz Contraction.

While we know today this is not the way stars generate all their energy, we know this is how the fusion process is started. Based on his assumption that the Sun built up all its heat as it was formed and radiating it away like a hot coal, Kelvin estimated the lifespan of the Sun to be about 30 million years.

The numbers posed a nagging contradiction–the Earth was older than the Sun. Thomson realized he needed to refine his calculations of the Earth’s age. In 1897 Thomson settled on an estimate that the Earth was somewhere between 20-40 million years old. This fit in nicely with his estimation of the Sun’s age.

Charles Darwin

Darwin, aged 45 in 1854, by then working towards publication of On the Origin of Species.

The age of the Earth was an important part to Darwin’s theory of evolution. As a geologist, he had conducted his own studies and concluded that the time needed to wash away the Weald, a valley in south-east England formed of the eroded remains of an anticline, would require 300 million years. Thomson believed that geologists were wrong to assume a steady rate of erosion. Floods and other natural disasters could accelerate this process. Thompson though the geologist’s thinking could use a dose of mathematical rigor. Though Darwin’s observations supported an old Earth, he was so bowled away by Thomson’s analysis that he removed any reference to time scales in later editions of his Origin of the Species.

A Quantum World

Thomson’s opponents argued that his time scales were too short for life to develop. He ignored them. With hindsight, it is easy to see that the brilliant Thomson was wrong and Darwin was right. But should we judge Thomson harshly for not listening to his opponents?

We must be careful when we judge the past and not look through the lens of our own experiences or biases. Thomson lived to 1907, to a time when radioactivity had firmly been established. The observation then by geologists that the Earth could be heated from within by radioactive decay meant that the Earth could be a lot older than Thomson thought. In fact, it was widely believed that the discovery of radioactivity invalidated Thomson’s estimates of the age of the Earth.

Higgs Boson

This image shows the Sun as viewed by the Soft X-Ray Telescope (SXT) onboard the orbiting Yohkoh satellite

Despite the discovery of radioactivity, Thomson refused to acknowledge this. He had strong reason to believe that the Sun was younger than 20 million years. Even with an old Earth, without sunlight, there could be no explanation for the sediment record on the Earth’s surface. It wasn’t until the discovery of fusion in the 1930s that this paradox was resolved.

While history has proven Thomson wrong in this debate, we must remember one thing. Given what we knew at the time, Thomson’s calculations and conclusions were correct–his science was sound. We can not fault Thomson for this.

The Higgs Boson Course

Higgs Boson Collision

Data from the CMS experiment, one of the main Higgs-searching experiments at the Large Hadron Collider. Image: CERN

The Higgs boson is the latest addition to our understanding of what happens in our Sun. Just like Thomson demanded a certain mathematical rigor, so too does “The Discovery of the Higgs Boson” course. The course recommends that the week’s module should take about two hours. Though it has been some time since I last sat in a Physics class and while the concepts and proofs were not entirely new, it does take some time to view the lectures and complete the exercises. I think students will realistically have to dedicate more than two hours to complete the week’s exercises.

Overall, it is a strong course that demands a lot of its students. I look forward to the rest of the course.