The Physics of Science Fiction

New Book about the Physics of Star Trek!

2013-04-14T10:27:00.000-07:00

I have just published a new ebook on Amazon. You can find it here. It's titled Star Trek: Neutron Stars, Antimatter, and Other Topics in Physics.

"This work explores the physics behind concepts covered in Star Trek: The Next Generation episodes.

The vastness of space and our sheer curiosity of the unknown drive us to understand more about the universe, to seek answers to age old questions, and to explore.

From magical eddies of space plasmas to particles with unknown properties and mysterious solar events, this book takes on all horizons of known physics and gives the reader simple explanations of amazing phenomena."

Star Trek: Tidal Locking

2012-08-06T16:26:00.002-07:00

Star Trek the Next Generation (1987-1994) (Picture)
Season 2, Episode 10
The Dauphin

During "The Dauphin" the crew heads to a planet engulfed in a Civil War. This planet rotates once per time it circles its sun, meaning that one side of the planet is always light and the other is always dark. This phenomenon is called tidal locking.

How does tidal locking work, does it actually happen, and what are the consequences?

Why does tidal locking occur?

Tidal locking occurs due to tidal forces. These forces might sound like they are related to the tides, and that's because they are.

The moon is responsible for the tides we experience on the earth. When we go to the beach there are high tides and low tides. Why is the ocean not always at the same level? The answer is that the gravitational force of the moon pulls on the earth's oceans.

Imagine the moon above one location of the earth, as shown in the top picture. The moon pulls on the earth: close to the earth it pulls on the oceans, a middle distance away it pulls on the core/center of the earth, and on the other side it pulls on other oceans.

Tidal forces, showing how the moon causes tides on the earth, for example (Source)

The force of gravity falls of like 1/r², so the gravitational attraction of the moon is strongest on the close side and weakest on the far side of the earth. The oceans nearest to the moon therefore rise, because they are being pulled toward it. On the far side the oceans are pulled least, meaning they are also at a maximum.

This is a little counter-intuitive. You might believe the oceans on the far side of the earth would be pulled around the earth to the other side (at least a little bit), but the tidal forces act more strongly on the earth between the oceans on the opposite halves of the earth. This means the moon is effectively pulling the earth out from under the ocean on the far side of the earth.

Tidal locking works by the same principles. Let's just think about how gravity can cause the moon to rotate around the earth so that only one side of the moon is ever facing the earth.

The answer has to do with torque. Torque is the reason you use a wrench, not your hands, to unscrew something.

Torque

When you go to open a swinging door, where do you push? Near the hinges, or further out? It's easier to open a swinging door by pushing further from the hinges because here you are applying more torque for the same applied force (how hard you push). Try pushing the door open near the hinges and it will be much more difficult.

How a wrench applies a torque. The longer the wrench, the more torque that can be applied and the easier your job becomes (Source)

Torque is defined as τ = r x F, where τ is torque, r is the distance from the axis of rotation, and F is the force applied to the door. The "x" means that it is a cross product (only the force applied perpendicular to the door contributes to the torque).

As much as the moon might seem like a sphere, it isn't. Similar to the way the moon pulls on the earth to produce the tides, the earth pulls on the moon to lock its orbit.

To see how this works, I want to make another analogy. When you spin a top it wobbles a bit and then evens out. This has to do with little corrective torques pulling on the top until it settles into its spinning position. In the same way, when the moon was first rotating around the earth it was spinning. Then the earth's little corrective torques pulled on the moon and it settled into a state where it does not feel net torques from the earth.

Just to be clear...

The moon is tidally locked with the earth only because it is not perfectly homogeneous. If it was a perfect sphere of perfect uniform radial density then it could not be tidally locked, because there would never be net torque from the earth. It is only because the moon is inhomogeneous that there are small bulges here or there on the surface that the earth can effectively pull on. This is analogous to the idea that if you spin a small metal ball it cannot wobble because gravity cannot apply a net torque to it.

Examples of tidal locking

The moon is a good example of tidal locking, but there are others. For example, it is believed that binary star systems are tidally locked, especially when the two stars have about equal masses.

Star Trek: Orbits

2012-07-29T14:59:00.001-07:00

Star Trek the Next Generation (1987-1994) (Picture)

During Star Trek episodes it is all too common to hear Captain Picard say "standard orbit, Mr. LaForge." This puts the ship close enough to the planet to keep it moving in circular motion around it.

Synchronous orbit is also sometimes requested. What is the distinction between the two, and what physics is required to keep a ship in orbit?

Orbits from a classical mechanics perspective

From the perspective of classical mechanics, a ship in standard orbit is an easy problem. There is a simple force balance equation that needs to be solved, namely:

GMm/r² = mv²/r

This simplifies to:

GM = v²r

where G is the gravitational constant 6.673 x 10^-11 m³kg^-1s^-2, M is the mass of the planet, v is the linear velocity of the ship around the planet, and r is the distance between the center of the planet and the ship. Note: the velocity and distance from the planet required for the ship to remain in orbit is independent of the mass of the ship.

What a satellite looks like in orbit around the earth. In my equations m_s = m and m_e = M (Source)

Since G and M are known, it is up to Mr. LaForge to choose a proper velocity and distance from the planet. He has infinitely many choices because he has two free parameters. Let's look at a quick example of the Enterprise in orbit around the earth:

G = 6.673 x 10^-11 m³kg^-1s^-2
M = 5.97 x 10²⁴ kg

Geordi chooses to place the ship about 10 km from the surface of the earth. Since the radius of the earth is about 6378 km that means:

r = 6388 km = 6.388 x 10⁶ m

By then solving for v, the Enterprise must be traveling with a linear velocity of

v = (GM/r)^1/2 = 7898 m/s

in order to remain in orbit around earth.

Synchronous orbit

Sometimes Picard needs to be in "synchronous" orbit around a planet. This means that the ship remains above the same point on the planet while in orbit. This introduces another constrain into the equation we used above:

GM = v²r

The constraint is that the angular velocity ω of the ship must be the same as the angular velocity of the planet. The angular velocity of earth, for example is one revolution per day. This corresponds to 2 pi radians per 24 hours. There is a useful relation between linear and angular velocity: v = rω. Reformatting our equation we get:

GM = ω²r³

Since the angular velocity ω is that of the earth, there is only one unknown: r. We can solve this example for earth. On earth the angular velocity turns out to be:

ω = 7.27 x 10^-5 radians/s

Then solving for r we get:

r = (GM/ω²)^1/3 = 4.22 x 10⁷ m = 3.58 x 10⁷ m from the surface of the earth

The corresponding linear velocity v of the ship would be

v = rω = 3071 m/s

In this way, using only the mass of the planet he is trying to orbit, Mr. LaForge can choose a velocity and distance from the surface of the planet that will allow the ship to orbit the planet.

Satellites

Satellites traveling around earth employ the same physics to keep them in orbit.

A satellite in orbit around earth. (Source)

There are even geosynchronous satellites. What do you think they do? They orbit the earth and remain above the same point on the earth's surface, like the Enterprise does when it is in synchronous orbit around a planet.

Star Trek: Neutrinos

2012-07-28T06:00:00.000-07:00

Star Trek the Next Generation (1987-1994) (Picture)
Season 2, Episode 8
A Matter of Honor

In an episode where Riker becomes first officer of a Klingon ship, there was a brief mention of neutrinos. A beam of neutrinos was used to remove organisms from the hulls of ships.

You may have heard of neutrinos, cute and mysterious little particles, but what are they and where do they come from? Could they actually be used to rid a ship of organisms?

What is a neutrino, exactly?

Neutrinos are very tiny neutral particles that until recently were believed to be massless. They were first observed in β decaying isotopes, which emit neutrinos during the decay.

Neutrinos are hard to "see" because they are very weakly interacting. They can penetrate almost anything without there being any sort of interaction. They commonly pass all the way through the earth without any noticeable interaction.

This is why neutrino detectors are very large. The image below shows the Super-Kamiokande detector in Japan. It can hold 50,000 tons of ultra-pure water when in operation. The small golden dots on the detector are photomultipliers. Since they interact so infrequently, a large detector is needed to give as much of a chance as possible to "see" a few neutrinos.

Neutrino physicists tend to have to deal with very small data sets because neutrinos are so difficult to detect.

Super-Kamiokande, a neutrino detector in Japan (Source)

Neutrinos, in addition to being small and hard to detect, travel near the speed of light. Recently is was actually believed (due to the OPERA experiment) that they traveled faster than the speed of light! It seems now that a faulty cable or two were to blame for the superluminal measurements.

These fascinating little particles come in three "flavors": electron, muon, and tau.

Where do neutrinos come from?

Some of the many places neutrinos in our galaxy come from are: nuclear reactors, the sun, supernovae, and the Big Bang.

In nuclear reactors, typically Uranium-235 is fissioned (split) by neutrons. The products of such a reaction are incredible varied. All elements smaller than Uranium-235 have some probability of being produced in the reaction. Many of these products are radioactive, and some of them reach stable modes via β decay. Neutrinos are emitted along with a positron or an electron during the decay.

β- and β+ decay (Source)

In the sun, you may know that hydrogen "burns" to produce energy and helium. During this process, hydrogen nuclei (protons) fuse together. In this case, four protons fuse to create a helium nucleus. However, a helium nucleus has by definition only two protons. In order to achieve this, two of the protons must "convert" to neutrons. This occurs via β+ decay, in which a proton converts to a neutron and emits a positron and an electron neutrino.

The same types of nuclear processes occurred during the Big Bang and during supernovae: when heavier elements are created via fusion it is often necessary to convert protons to neutrons, and occasionally the opposite is true. In the case of a neutron converting to a proton, an electron and an anti-neutrino are emitted in a process called β- decay.

Why do physicists seem to think it is impossible for neutrinos to travel faster than light?

Light has been said to be a sort of cosmic speed limit. When Albert Einstein and others developed the theory of relativity, the central principle was that the speed of light is constant in all frames and nothing with mass can travel as fast or faster than the speed of light.

Since neutrinos have mass, the existence of superluminal neutrinos would violate of Einstein's theory of relativity. As it stands, the theory holds that it would take an infinite amount of energy to accelerate anything with mass to the speed of light.

Neutrino beams on the Enterprise

Unfortunately, I'm going to have to be a killjoy. I don't see how it would be possible to use a neutrino beam to rid a ship's hull of an organism. As we've seen already, neutrinos are very weakly interacting. The vast majority of the neutrinos would pass right through the organisms and the entire ship. It would probably make more sense to use a laser to rid the ship of the pesky organisms.

Bonus: neutrino oscillations

There is an obvious question here: how do we know neutrinos have mass? If it turns out they don't have mass, then maybe there is no violation of relativity. And maybe there is some new physics in all this.

As it turns out, neutrinos have a special way of telling us they have mass: they "oscillate."

What this means is that they change between their three forms. Imagine a chameleon. This chameleon lives in a three sided room. One wall is green, another red, and the last one is blue. Depending on where in the room the chameleon goes it will choose to blend in with the red, green, or blue wall color. Neutrinos act somewhat like this chameleon; as they travel through space near the speed of light, they switch between their three flavors. Electron. Muon. Tau. Muon. Tau. Electron.

A diagram showing that neutrinos oscillate between their three forms (Source)

It turns out that this property, the ability to oscillate between three forms, requires mass. And thus we know neutrinos have mass, and therefore observing superluminal neutrinos would be a contradiction of relativity.

Star Trek: Artificial Gravity

2012-07-25T14:18:00.001-07:00

Star Trek the Next Generation (1987-1994) (Picture)

The artificial gravity on the Enterprise has always confused me a little bit. I want to know how they do it!

Where does gravity come from and how can it be simulated in outer space? As it turns out, there are many ways to artificially simulate gravity.

Where does gravity come from?

Gravity is the force that Sir Isaac Newton famously "discovered"after watching an apple fall from a tree. It is something we have come to take for granted. When we throw a ball up in the air we know it will come back down. We know gravity exists, but where does it come from?

Gravity is an intrinsic property of mass. All mass attracts other mass by a force called gravity. When I stand on the earth, it pulls me down, towards its center. But I also pull on it a little. Since the gravitational force a body exerts is proportional to its mass I pull the earth toward me a lot less than it pulls me toward it.

The expression for gravitational force is:

F = GMm/r²

where G is the gravitational constant, M is the mass of the larger object, m is the mass of the smaller object, and r is the distance between them.

If you were interested in the acceleration of an object on earth you would apply Newton's second law:

F = ma

This yields:

a = gravitational acceleration = GM/r²

The acceleration of all objects on earth is therefore the same. It is independent of their mass. This might seem weird, but it isn't. The reason this is not intuitive is because most objects on earth experience other forces while in motion, like air resistance. This is why a feather falls more slowly than a lead brick. If both were in a vacuum (no air molecules) then they would fall at the same rate.

One interesting thing about gravity (just something to think about) is that it is only attractive. There is no negative gravity - there would need to be negative mass to achieve negative gravity. Even antimatter is comprised of positive matter. The other forces, like electricity and magnetism, have attractive and repulsive properties. Why should gravity be only attractive?

What is artificial gravity and why is it necessary?

In outer space people are no longer on a planet. Looking back at the equation for gravitational force we can see that the force depends on the distance between the two objects, and it drops off quickly as the distance increases because that dependency is squared. A spaceship in outer space barely feels the effects of a planet's gravity, unless it gets fairly close to a planet (or a star). Therefore there will be no preferred direction like there is on earth. Each direction will "pull" or not pull a person equally. That is why astronauts look like they are floating: there is no force to pull them to one place on a ship.

Astronauts in zero gravity training (Source)

On the Enterprise everybody stands upright. How do they simulate gravity on their ship? There are several possibilities; I explore a few of the most interesting ones below.

Rotational/centrifugal methods

The easiest way to simulate gravity is to provide another force that is about equal in magnitude. One way to do that is to rotate a space craft.

Have you ever been on the teacup ride at Disney Land, or taken a sharp curve while driving? In both cases you may have felt like the outside of the teacup or car applies a force to you to keep you in - either in the teacup or the car. This principle can be applied to simulate gravity.

A point on the edge of a rotating body has a linear velocity which we will call v. Objects with a velocity always wants to continue in a straight line. In order to keep that point (in this case, a person in a space craft) from flying outward in a straight line, a force directly in toward the center of the rotating body needs to be applied to the person. This force will appear to push the person in from the outside walls of the space craft, like gravity would.

Circular motion. The black arrows represent velocity and the blue arrows show the inward force required to keep the ball in a circular orbit. (Source)

Let's take an example of how this might be done. Assume there is a hollow wheel with a radius of 10m. In order to simulate gravity the wheel will have to spin with a certain speed (v is the linear velocity and ω is the angular velocity):

acceleration = gravity = v²/r = ω ²r

Solving for ω we get that the wheel would have to rotate about 9.5 times per minute in order to simulate the gravity we feel on earth. This is definitely achievable.

The enterprise is not continually rotating, though, so it must simulate gravity in another way.

Linear acceleration

Gravity can also be simulated by a linear acceleration, like when you speed up in a car and feel like you are being thrown backward. The Enterprise does not appear to employ this method, either.

Mass

Gravity is an intrinsic property of mass, right? So why don't you just squash a lot onto the bottom of the Enterprise so it pulls people down and they can stand on the ship? Well this can also work in theory, though it will require a lot of mass. For kicks, let's coat the bottom of the Enterprise with matter from a neutron star.

Neutron stars have a density of about 4 x 10¹⁷ kg/m³ (Source)

If we estimate the mass to be applied about 5 meters below the people on the ship (lots of problems with this, but I'm going to ignore them) we can use:

gravity = GM/r²

M = gravity*r²/G ~ 3.67 x 10¹² kg

This is a lot of mass, but neutron stars are incredibly dense so it might not be a problem. This corresponds to about 10^-5 m³ of neutron star matter. This is not much at all, only about one tablespoon of neutron star!

Of course there would be lots of difficulties in procuring a sample of neutron star, but nevertheless it's fun to think that it could be used for something as interesting as simulating gravity on a space ship.

The idea of using incredibly dense matter to simulate gravity on a ship is a cool idea - and very exotic!

Star Trek: Sound in Outer Space and on Other Planets

2012-07-24T18:45:00.004-07:00

Star Trek the Next Generation (1987-1994) (Picture)

In Star Trek there is little or no mention of the fact that outer space is a vacuum. There is not air to breathe and no matter to provide resistance to a spaceship.

It is interesting to consider the properties of sound waves and the effect of outer space on how we are able to communicate.

Outer space is a vacuum

Outer space is a vacuum. There is no air in outer space. That is why we cannot breathe in outer space. It is also why we cannot speak in outer space.

In the title illustration, there are air particles between the speaker and a human ear. There is a banding pattern of the air molecules. This is the way sound travels: through waves in the air. These waves take the form of a pattern of higher and lower density of air molecules. The sound waves propagate through space by moving through the air this way, in pressure waves.

When the waves reach your ear they are transferred from the ear to the brain in the form of signals sent by nerves. This is how we hear.

Now imagine the air particles in the above picture are gone. Sound can no longer travel through the space between the speaker and the air. This is because sound requires a medium to travel. This is in notable contrast to photons, which can travel through empty space. An example of photons is visible light.

A "ringing" bell in a vacuum makes no sound (Source)

Since outer space has no air, there is no medium through which sound waves can be transferred. This means no sound waves can propagate in outer space.

This brings about what is probably the more interesting question: does it matter what the medium for sound propagation is? The answer is yes!

Propagation of sound waves is dependent on the medium

I'm sure some people have inhaled helium at a party at some point in his/her life in the hopes of achieving a high pitched voice.

In this case the medium for sound propagation is different than usual. Instead of normal air, your lungs are filled with helium. Helium atoms are much lighter than nitrogen and oxygen, which are the most common constituents of air. Heavier gases propagate sound more slowly than light gases.

When a person talks he/she imparts a lot of different wavelengths of sound to the air. Heavier gas molecules propagate the sound more slowly, giving the sound waves a lower frequency than lighter gas molecules. Therefore, the sound waves in helium have a high frequency (squeaky pitch).

Another phenomenon that contributes to the high pitch of a sound propagated by a light gas has to do with resonance.

Resonance

We experience resonance on a regular basis, though we may not recognize it. Do you like to double bounce people on a trampoline or have you ever pushed somebody on a swing? Both are examples of resonance. Here, timing is important. By pushing or bouncing at the resonant frequency of the swing or trampoline it is possible to make the person swinging (or the other person bouncing on the trampoline) achieve maximal amplitude for the effort you put into pushing or bouncing.

A graph showing the spike in amplitude at the resonant frequency (Source)

In gases like air or helium there are resonant frequencies as well. For heavy gases these resonant frequencies are smaller, corresponding to deeper tones, than they are for lighter gases. Helium is a very light gas and therefore has a high resonant frequency. These resonant frequencies are magnified relative to others by the same effect as you achieve by double bouncing somebody on a trampoline. Thus high pitched sounds are magnified in helium.

How would this affect Star Trek?

Star Trek characters do not (as far as I have seen) float in outer space and try to talk to one another. They do, however, visit foreign planets.

If it were to be perfectly realistic, their voices should change pitch somewhat on each planet, according to the composition of each planet's particular atmosphere.

I accept the assumption that planets which can support humanoid life likely have approximately the same atmospheric composition as earth. However, there is one way to dramatically change the atmosphere: replace nitrogen, which comprises about 79% of the earth's atmosphere, with another inert gas, like Argon or Krypton, which is much heavier. I imagine that all the characters' voices would sound much deeper. It may also be possible for humanoids to live on such a planet. I would like to see an episode address this phenomenon. I think it would be fun!

Star Trek: Galactic Cosmic Rays

2012-07-24T17:12:00.001-07:00

Star Trek the Next Generation (1987-1994) (Picture)

In outer space there is a type of very high energy radiation called galactic cosmic rays. These rays are comprised of charged particles, like atomic nuclei and electrons. They are one of the two major contributors to the radiation dose received by astronauts (the other coming from solar particle events), and the only one that it has been impossible to shield against thus far.

These galactic cosmic rays are ubiquitous in outer space.

While they are never, or very rarely, mentioned during Star Trek, they are a very important part of travel in outer space, and it is vital that astronauts and engineers know about them before leaving the safety of the earth's atmosphere.

Origins of galactic cosmic rays (GCRs)

Galactic cosmic rays, commonly referred to as simply cosmic rays, are believed to originate within our galaxy but outside our solar system.

They probably originate from supernova explosions. During a supernova much of the mass of a star explodes outward, carrying with it a large amount of matter. This matter is ionized, meaning that the atoms are stripped of their electrons, during the process. When these ions and electrons, now separate, are in a magnetic field, they accelerate. The magnetic fields coming from the remnants of the supernova are responsible for accelerating many of the ions to high velocities, approaching the speed of light. Those ions and electrons that achieve very high energies are called cosmic rays.

With very little to stop them (outer space is a nearly perfect vacuum) the cosmic rays can accelerate to extremely high velocities. When they become energetic enough they are able to escape the area containing the remnants of the supernova. They shoot off into the rest of the galaxy, bending and accelerating in local magnetic fields as they pass stars and planets.

Some of these cosmic rays find their way to earth and physicists study them.

How energetic are cosmic rays?

Most cosmic rays have energies between 10 MeV and 10 GeV, where MeV is Mega electron volts and GeV is Giga electron volts. An electron volt is the energy required to accelerate an electron through a 1-volt potential. The energy of air molecules at room temperature is about 0.0385 eV.

The most energetic cosmic ray detected to date had an energy of about 3 x 10²⁰ eV. That is 40 million times greater than the highest energy protons ever produced by a particle accelerator on earth!

Basically, the universe is an incredible particle accelerator.

How can cosmic rays be detected?

When cosmic rays enter the earth's atmosphere they collide with molecules in the air, mostly oxygen or nitrogen. This interaction produces a massive shower of light particles that rain down onto the earth's surface. Particle detectors on the surface (or in the air) can recognize the shower of particles as a cosmic ray.

A cascade of particles originating from a cosmic ray and various detectors at the Pierre Auger Observatory in Western Argentina (Source)

The detectors are most effective in areas of high altitude, with as little atmosphere as possible separating outer space and the detectors. High altitude locations in Colorado and Argentina are primary research locations for the study of cosmic rays.

Cosmic ray spallation

One of the most fascinating effects of cosmic rays is cosmic ray spallation. When cosmic rays collide with other objects, be it a molecule in the air or even another cosmic ray, a shower of particles results. This shower includes many particles that were produced by the collision. In this collision some of the kinetic energy of the cosmic ray is transformed into matter, in the form of light particles.

Shortly after the Big Bang, cosmic ray spallation is believed to have been responsible for the abundance of some of the light elements in the universe, including lithium, beryllium, and boron. Isn't that neat?

Now to connect back to Star Trek:

Why would the Enterprise need to worry about GCRs?

As already described, cosmic rays are present throughout the universe. They are very high energy and therefore very penetrating, capable of passing through very thick and dense matter.

Astronauts today cannot shield themselves from cosmic rays. This high energy radiation, including protons and even iron nuclei pass right through a person, damaging DNA along the way. This is a significant source of radiation damage and astronauts are believed to be at greater risk for central nervous system damage. Cosmic radiation is likely the leading cause of this concern.

An astronaut is at high risk of DNA damage due to cosmic rays (Source)

While on the Enterprise, there would need to be a way of mitigating the effects of cosmic radiation, as it is considered to be one of the greatest roadblocks to pursuing interplanetary travel with a human crew.

It is possible that the doctors in the 24th century are capable of offering medication to reverse chromosome damage resulting from radiation, because in Season 1, Episode 17 of Star Trek: The Next Generation Dr. Crusher is able to provide medication to the people of Aldea to reverse the damage done to them by radiation. Perhaps that is the kind of technology humans will need in order to pursue interstellar travel.

Star Trek: Binary Stars and Pulsars

2012-07-23T16:04:00.001-07:00

Star Trek the Next Generation (1987-1994) (Picture)
Season 1, Episode 23
We'll Always Have Paris

In search of the source of a time disturbance, Picard and the Enterprise follow a relay signal to a binary star system. There they find the source of the disturbance and the scientist responsible.

What are binary star systems? Properties of these systems can provide insight into the nature of space and time.

Binary Star Systems

Binary star systems are systems of two stars that orbit around a common center of mass. The brighter of the two stars is called the primary star, and the other is the companion star. These systems can be observed by monitoring the intensity of the radiation coming from the system at a distance. When one star eclipses the other the intensity drops because the intensity from both stars in no longer being observed. Sometimes binary star systems can also be observed by telescopes directly.

The orbits of binary stars (Source)

In the Star Trek episode the companion star in the binary star system is supposedly a pulsar.

Pulsars

Pulsars are highly magnetized neutrons stars that rotate and emit beams of electromagnetic radiation. In order to understand more about pulsars, it is important to know what neutron stars are.

Neutron Stars

Neutron stars sometimes form during the collapse of massive stars. They collapse to a very small sphere, comprised almost completely of neutrons. Neutrons are subatomic particles comprised of two down quarks and an up quark. They are found in the nuclei of almost all atoms. In normal matter atoms take up a lot of space because the nuclei are surrounded by a lot of space and electrons. In this way, matter is mostly empty space and it is the electrons surrounding the nuclei which are responsible for your ability to sit on a chair without falling through or to stand on the earth.

A basic diagram of the inside of a neutron star (Source)

In neutron stars this empty space disappears. When the star can no longer burn nuclear fuel, there is no longer an outward pressure created from the emission of energy from the fusion process. This sparks the supernova and what remains falls inward under the force of gravity. What it left is an extremely dense sphere of neutrons.

Neutron stars tend to be approximately 20km in diameter and contain approximately 1.5 solar masses, which is 1.5 times the mass of our sun. In a neutron star, the matter is packed so densely that one teaspoon of neutron star matter would weigh one billion tons on earth!

So Pulsars Are...

Pulsars (pulsating stars) are neutron stars with very strong magnetic fields, which emit strong beams of radiation. These beams of radiation are emitted along the magnetic axis of the pulsar, which is not always the same as the rotational axis of the pulsar. The radiation beam is therefore seen once per rotation of the pulsar. The pulsars rotate quickly because they are formed from very massive stars, which have some angular momentum. By conservation of angular momentum, when the star collapses to a neutron star its angular velocity increases greatly. Thus pulsars rotate with very high frequency and the beams of radiation, which span the gamut from radio waves to gamma rays, are separated by a very short amount of time.

A diagram of a pulsar. Note that the magnetic axis is not the same as the axis of rotation. (Source)

With each pulse of radiation the neutron star loses a small amount of energy (relative to its total energy). In this manner it begins to slow down over time.

What do pulsars have to do with space and time?

Pulsars are extremely dense objects, meaning the gravitational fields are very strong near them. If you imagine space-time as being a grid that expands through the universe, points of high density, like pulsars (and black holes) would look like sharp dents in the fabric of the universe. These sharp dents therefore warp our perception of space and time at those points.

Therefore, since the scientists in Star Trek were interested in carrying out time experiments, it makes sense that they would choose to be located near pulsars. Near dense objects, our perception of space and time are different than how we experience them on earth. These two phenomena, which seem so separate in our lives under most conditions, are inextricably linked. By studying pulsars we can gain some insight into the relationship between the two.

Star Trek: Antimatter

2012-07-20T05:41:00.000-07:00

Star Trek the Next Generation (1987-1994) (Picture)
Season 1, Episode 22
Skin of Evil

The Enterprise comes in contact with a creature made out of an oily substance, which calls itself Armus. It is the embodiment of evil. In its haste to get to the planet Amus inhabits, the Enterprise must realign the dilithium crystals for its warp core. The warp core supposedly runs on an antimatter reaction. What is antimatter, and is it enough to power a ship like the Enterprise?

What is Antimatter?

You may be wondering whether antimatter is a real thing. I mean dilithium crystals are not real (at least not the way they are presented in Star Trek) so why should antimatter be real? It could very well just be a device the writers used to explain where the ship gets all its energy.

As it turns out, antimatter is real. For every piece of matter there is a corresponding piece of antimatter. For example, we have protons. Therefore, antiprotons also exist. We have electrons and also antielectrons (called positrons). These antiparticles have the same mass but they have opposite charge and quantum spin. We will ignore the quantum spin part - let's just focus on the fact that they are opposites.

Because the positron and electron have the opposite charge, they attract one another. When they come together, they annihilate!

Annihilation

Annihilation is derived from the Latin word nihil, meaning "nothing." When the electron and positron annihilate, all their mass disappears, becoming energy. This applies to all matter-antimatter pairs, including protons and antiprotons, or neutrons and antineutrons.

A representation of the annihilation process (Source)

The energy is released in the form of two photons, which are electromagnetic radiation (of any and all energy levels). These photons each carry half of the energy released in the reaction.

How much energy is released in the reaction?

Remember Einstein's famous equation E = mc²? Well, this is one of the places it is relevant. The energy released in the reaction is equal to the change in mass times the speed of light squared. This is a lot of energy.

On the Enterprise they use deuterium-antideuterium reactions in their warp core. Deuterium is an isotope of hydrogen. Its nucleus has a neutron and a proton, instead of just the one proton in regular hydrogen. Let's see how much energy is produced from the annihilation of one gram of deuterium with one gram of anti-deuterium:

This means we have two grams of mass and it is being annihilated completely:

E = mc² = 0.002kg x (3 x 10⁸ m/s)² = 1.8 x 10¹⁴ Joules

For a comparison, the energy yield of Fat Man, the bomb dropped on Hiroshima during WWII, was estimated to be about 8.8 x 10¹³ Joules.

It is evident that matter-antimatter reactions are incredibly powerful and can supply almost unimaginable amounts of energy. In fact, there is no other process in the universe that can produce energy more efficiently.

And it can go backwards!

It is possible to produce antimatter from energy. In fact, it is all around us, though it does not survive long before annihilating. Here's my favorite example: bananas.

Bananas have potassium, and potassium is good, right? Of course potassium is good - but it is also radioactive! All potassium contains about 0.012% Potassium-40. This is a radioactive isotope of potassium, and it decays by a method called β+ decay. In this process a proton in the nucleus converts to a neutron and emits a positron!

Bananas are a source of antimatter! There you have it. Share the information with your friends or keep the secret to yourself.

Seriously, though, don't be afraid of bananas. They are a good example because they have a lot of potassium, but all potassium sources have the same percentage of potassium-40, so you are not actually doing yourself any good if you avoid bananas and get your potassium elsewhere. Also, you need potassium, so you cannot just avoid it completely.

A diagram of pair production (Source)

Another example of how the process can go backwards is called pair production: a high-energy photon is traveling at the speed of light (because a photon is light) when it comes upon a nucleus. When it comes close to the nucleus, it can interact, producing an electron-positron pair. The positron will go on to very quickly annihilate with a nearby electron.

The condition for pair production to occur is that the incoming photon must have at least the energy required to produce the mass for an electron and a positron. This corresponds to about 10^-13 Joules. This is not much compared to the annihilation process we saw above, but it is a lot of energy for one photon to have. Only high-energy gamma rays are capable of pair-production reactions.

Star Trek: The Physics of Solar Flares

2012-07-18T15:36:00.000-07:00

Star Trek the Next Generation (1987-1994) (Picture)
Season 1, Episode 21
Symbiosis

When the Enterprise comes the the aid of a small freighter, the crew discovers two cultures that have come to be dependent on one another for survival. Solar flares from the nearby sun make it difficult to rescue these people from their freighter, because the flares are interfering with the electronic equipment on the Enterprise. What are solar flares, and can they really be powerful enough to interfere with the Enterprise's electronics?

Solar flares

A solar flare is a sudden large release of energy near a star's surface. With each flare electrons, ions, atoms, and a large amount of electromagnetic radiation are ejected.

The ions, electrons, and atoms are not very penetrating. Most of them, even the energetic ones, can be stopped by a small amount of shielding - the Enterprise's armor, for example. These forms of radiation are pretty easy to stop because they have fairly strong interactions with other matter.

The more worrisome radiation is the electromagnetic radiation. This includes a wide range of possible energies, and therefore wavelengths of electromagnetic radiation.

A diagram of the electromagnetic spectrum (Source)

The entire spectrum of electromagnetic radiation above is represented in a solar flare, though the bulk of the radiation is high energy, meaning x-rays and gamma rays. This radiation is much more penetrating, because it does not interact with matter as frequently, or as strongly as electrons, ions, and atoms.

During the episode Lt. Worf says that a burst of x-rays is disrupting their electrical systems. The fact that a large amount of x-rays have bombarded the Enterprise is unsurprising, given the fact that it has gone close to the source of the solar flares. There should also be a large amount of gamma radiation produced. However, I am not convinced that the x-rays (or gamma rays) should be the primary source of concern when it comes to the electronics. I think there is another much more legitimate mechanism for the solar flares to interfere with the electronics aboard the Enterprise.

How do solar flares interfere with electronics?

Solar flares are produced in the sun, which is chock full of high-temperature plasma. Plasma is the fourth state of matter, an ionized gas. In stars, the ionized gas is often comprised primarily of hydrogen and helium ions. For all of the ions there are also the electrons that have been pulled away from the nuclei. When a great number of charged particles, both positive (ions) and negative (electrons), move very fast, they produce strong and turbulent magnetic fields. Magnetic fields, in turn, induce current to flow in conducting materials.

Electronics rely heavily on electrical currents and are therefore confused or broken by strong magnetic fields.

Have you ever held a magnet up to an old tv? If you have, you will know that it distorts the colors on the screen, sometimes permanently. This is because old tvs render images on their screens by shooting electrons at bits of phosphor. When a magnet is brought close to a tv, it deflects electrons away from their intended targets, causing the wrong colors to be presented on the screen.

The effect of a magnet on an old tv screen. (Source)

In the same way, magnetic fields can disrupt other electronics, by sending electrons to the wrong place, or at the wrong speed.

Thus the extra-turbulent magnetic fields produced by the solar flares in the Star Trek episode could very reasonably be responsible for interference with electronics. One thing I do not want to overlook, though, is that magnetic fields can often be shielded against by surrounding electronics with conductive or magnetic materials. I do not know whether the Enterprise would have sufficient magnetic shielding to not feel the effects of the magnetic field from the solar flares on the electronics.

I do not believe, however, that bursts of x-rays or gamma rays would affect electronics much. X-rays and gamma rays are uncharged radiation, meaning they do not produce magnetic fields. They are more dangerous to living things, because they can damage DNA, than they are to electronics. In fact, many electronic devices are used to collect information about x-rays and gamma rays.

Despite what I just said, large amounts of any kind of radiation can permanently damage or destroy electronics, as well as anything else. In believe, however, that in this case the signal interference would most likely come from the strong and turbulent magnetic fields generated by the solar flares.

Reference
Spaceref.com

Star Trek: Supernovae and Element Scanning on Angel One

2012-07-17T13:37:00.000-07:00

Star Trek the Next Generation (1987-1994) (Picture)
Season 1, Episode 13
Angel One

An away team beams down to Angel One in order to look for a lost freighter crew. The crew has apparently hidden away on the planet, so the Enterprise must use advanced scanning technology to locate them. There are elements not endemic to Angel One that the crew would have brought with them. By scanning the planet for platinum, the Enterprise is able to locate the freighter crew. How would such a scanning technology work, and is it realistic?

First let's ask an important question:

Is it realistic to believe a planet could have no platinum?

To that I am going to say yes. Planets are formed from swirling clouds of matter that are created from the detritus of old supernovae.

But what is a supernova, exactly?

A supernova is a massive explosion that can occur when a star reaches the end of its life. It looks something like the image below.

What a supernova might look like (Source)

When a supernova occurs there are conditions of intense heat and pressure. These conditions cause heavy ion fusion, meaning that two atoms of carbon, for example, can fuse together to create a new, heavier element. This is the process that is responsible for forming the heavy elements we have in the universe.

If stars did not die so spectacularly then there would not be the rich variety of elements we have around us today (including those that make up humans and all living things).

Now back to platinum

I think it is realistic to believe that Angel One could have been formed from the remains of a supernova that was perhaps not energetic enough to produce a significant amount of heavy elements, including platinum.

The periodic table of elements. Note how far down Platinum (Pt) is. (Source)

Platinum is a relatively heavy element, which can be seen from the periodic table. It is located near the bottom right of the transition metals (pink part of table) and it has the symbol Pt. All of the elements required for mammals to live are lighter than platinum, meaning that a planet theoretically formed without platinum or any elements heavier than it could support life for beings like humans. I believe the heaviest element the human body requires is Iodine (I), which is on the far right of the periodic table. It is important because it enables the thyroid to produce hormones.

Now that we believe it is possible for a planet to be created without heavy elements like platinum and for life to exist without these heavier elements, it is important to return to the main question:

How might the Enterprise have scanned Angel One for platinum?

Assuming the Enterprise was only scanning the surface of the planet, I think this question has a pretty satisfactory answer: spectroscopy.

Spectroscopy

In its most common form, spectroscopy involves shining electromagnetic radiation on matter. If we look at the most well-used example, hydrogen, electromagnetic radiation is shone on a sample of hydrogen. Certain wavelengths are absorbed by the element and others pass right through. Those that are absorbed are equal to the energy difference between two energy levels of electrons.

Hydrogen energy level transitions with corresponding photon wavelengths absorbed. (Source)

The above image shows some of the energy level transitions allowed for an electron in orbit around a hydrogen nucleus (just a proton, in this case). The energy levels can be thought of as concentric circles around the nucleus. An electron usually lives in the one closest to the nucleus. In order to move up to a level further from the nucleus it needs to absorb a specific amount of energy. It only absorbs electromagnetic radiation that has the correct energy, and therefore the correct wavelength.

By shining all wavelengths of electromagnetic radiation on a sample and seeing which are absorbed it is possible to know the composition of what you are testing. After absorbing the electromagnetic radiation and moving up to a higher energy level, the electron eventually relaxes back down to its lowest energy state (ground state) by emitting electromagnetic radiation with energy equal to the energy difference between the two levels. Sometimes multiple transitions occur while an electron relaxes down to its ground state.

So, it works!

In this case, the physics supports the possibility of the Enterprise finding the freighter crew using spectroscopy. Of course they need to have very powerful and sensitive equipment to notice a small piece of platinum on an entire planet (and to be able to scan the planet so quickly), but I think we can give that much to a ship that can travel through the universe at warp 9!

Star Trek: Radiation Damage and Infertility

2012-07-16T19:17:00.001-07:00

Star Trek the Next Generation (1987-1994) (Picture)
Season 1, Episode 15
When the Bough Breaks

The Aldeans have incredible technology, which has managed to cloak their entire planet for thousands of years. Having advanced technology has come at a price, however. The cloaking device has depleted the planet's ozone layer and its people have become infertile due to DNA damage caused by ultraviolet radiation. The Enterprise reseeds the planet's ozone layer and Dr. Crusher offers them an antidote to reverse the damage done by the radiation. How closely does this match the actual effects of exposure to radiation?

Radiation Poisoning

The only radiation poisoning that people currently have reliable data on is the effect of acute doses of radiation. We are beginning to understand the long term effects of large acute doses of radiation by following the survivors of the WWII bombings in Hiroshima and Nagasaki.

The effects of long term exposure to radiation is not well understood, so it is unclear what would happen to the Aldeans if their ozone layer was depleted by their invisibility device. Let's start at the beginning and see what we can figure out.

What is Radiation?

In order to generalize a bit, let me explain what radiation is. It can be one of several things:

Electromagnetic radiation (everything on the electromagnetic spectrum, including visible light, microwaves, ultraviolet radiation, x-rays, gamma rays, etc.)
Charged particles, like a helium atom that has been stripped of its electrons and only contains the protons and neutrons in its nucleus. This is known as alpha radiation.
Energetic lone electrons whizzing through space are what is known as beta radiation.
On occasion neutrons can also fly through space alone. They do not last long though, because neutrons decay with a half life of about 11.7 seconds. I wouldn't worry about neutron radiation unless my room was right next to a nuclear reactor.

A visual of how penetrating different forms of radiation are. (Source)

These types of radiation can be further divided into ionizing and non-ionizing radiation. Ionizing radiation has enough energy to ionize an atom, meaning it can pull one or more electron away from its nucleus. Non-ionizing radiation does not have enough energy to pull an electron away from a nucleus.

Ok, so what about the Aldeans? In this case, ultraviolet radiation does fall into the ionizing radiation category, meaning it can do DNA damage.

But...

It's very likely that the Aldeans would die from cancer before becoming completely infertile. Ionizing radiation causes DNA damage, which can cause mutations in your DNA. These mutations have the potential to be cancerous.

The same process occurs to make a person incapable of having their own children: mutations to the sperm and egg cells, or to the organs that produce/release the sperm and eggs can cause them to become nonfunctional. Meaning no babies.

A look at how ionizing radiation damages DNA. (Source)

However, receiving a full body dose of radiation strong enough to eliminate a person's ability to replicate would also do terrible damage to their skin and would almost certainly cause cancer. Of course I'm speculating here because there is no data that I know of that has tracked people who receive reasonably large doses of continuous ultraviolet radiation, so we do not know how it affects their ability to reproduce. There was an allusion during the episode to the Aldeans having a skin condition that they needed medication to alleviate, so perhaps they all have melanoma and are able to cope with it. Maybe that is possible on Aldea.

To keep it simple: it is possible for radiation to prevent a person from being able to reproduce. The question now is whether that symptom would manifest before the Aldeans are on their deathbeds with cancer.

It's a good thing Dr. Crusher had an antidote!

About that antidote... I'm curious to know what it does. It supposedly fixes their damaged DNA so that the Aldeans will be able to reproduce again.

Ultimately, this is a good explanation for how the antidote can make an infertile person fertile again. It is not, however, possible to do anything of the sort today. The challenge is that the damage done to the DNA in each cell is fairly random: you don't know where in a chromosome the damage will be done and you don't know the nature of the damage that will be done.

Without going too in depth with this explanation about DNA damage, I just want to say that the cell has enzymes that are responsible for fixing damage that might be done by DNA. Humans evolved to be able to cope with small amounts of radiation or other factors that cause small mistakes in DNA and there are mechanisms to fix them. These mechanisms are not sufficient, however, to fix large or strange damages, such as those done by a large dose of radiation.

If I were to explain how Dr. Crusher's antidote worked to cure the Aldeans I would say that it contained very advanced enzymes that could pass through the plasma membranes of cells and into the nucleus of cells. These "advanced enzymes" would be able to fix the DNA in every cell, using remaining healthy cells as templates (they will be able to identify healthy cells from damaged cells because they are awesome... or because healthy cells meet a certain criteria. Namely the correct number of chromosomes and chromosome length).

Well... so ends my confused ramble about prolonged exposure to ultraviolet radiation as an explanation for infertility in the Aldeans. I hope some of it made sense.

Star Trek: Velara III and the Physics of Inorganic Life

2012-07-15T08:08:00.000-07:00

Star Trek the Next Generation (1987-1994) (Picture)
Season 1, Episode 17
Home Soil

Episode 17 begins with the mysterious death of one of the crew tasked with terraforming the uninhabited planet of Velara III. While trying to determine how he was killed, Geordi and Data discover a small light-emitting sphere. It turns out to be a form of inorganic life. In this post I will consider the implications of finding intelligent inorganic life.

How is life defined?

From wikipedia, the criteria for life is:

Homeostasis: Regulation of the internal environment to maintain a constant state; for example, electrolyte concentration or sweating to reduce temperature.
Organization: Being structurally composed of one or more cells, which are the basic units of life.
Metabolism: Transformation of energy by converting chemicals and energy into cellular components (anabolism) and decomposing organic matter (catabolism). Living things require energy to maintain internal organization (homeostasis) and to produce the other phenomena associated with life.
Growth: Maintenance of a higher rate of anabolism than catabolism. A growing organism increases in size in all of its parts, rather than simply accumulating matter.
Adaptation: The ability to change over a period of time in response to the environment. This ability is fundamental to the process of evolution and is determined by the organism's heredity as well as the composition of metabolized substances, and external factors present.
Response to stimuli: A response can take many forms, from the contraction of a unicellular organism to external chemicals, to complex reactions involving all the senses of multicellular organisms. A response is often expressed by motion, for example, the leaves of a plant turning toward the sun (phototropism) and by chemotaxis.
Reproduction: The ability to produce new individual organisms, either asexually from a single parent organism, or sexually from two parent organisms.

The inorganic light-emitting spheres seem to satisfy all the 7 criteria outlined above, so an inorganic being like the spheres would be considered alive.

But didn't Data and Geordi decide they're like transistors?

This is where the story takes an interesting turn. The small lights are comprised of silicon, germanium, and gallium arsenide... water, impurities, and sodium salts. Computers are made from transistors, so these life forms are like mini computers. When connected together by the saline water they form a massive computer, capable of intensive calculations. It is also claimed they are powered by solar energy.

A picture of Alan Turing, father of the early computer (Source)

The above photo of Alan Turing is presented because I want to propose an interesting thought question: the Turing test.

What is the Turing test?

The Turing test is basically a test to see if a computer can exhibit intelligent behavior. In the Star Trek episode the little computer beings, or "microbrains," do exhibit intelligent behavior, communicating with the crew of the Enterprise and sending complicated messages. They even hijack its computer systems.

If these beings were to be found, they would answer the question about whether computers can be intelligent. They might also answer a question about consciousness.

The microbrain, once it has grown (Source)

If the microbrain were deemed a conscious being, and I'm sure it would be, then it begs the question: what makes us different from them? How are people different from computers?

How could the microbrain have grown while on the Enterprise?

This bit of storytelling bothered me a bit. It was claimed that the microbrain was photosynthetic but it grew so quickly it couldn't have been. While duplicating it was seemingly creating mass. It was not taking mass from the Enterprise, so it had to be creating it from pure energy in a sort of anti-annihilation process. This is very energetically expensive, as Einstein could have told you:

E = mc²

That means to create 1g of mass it would take 9 x 10¹³ Joules (a Joule is a unit of energy). If the room the microbrain was in contains about 10 square meters of floor space, that space can be estimated to receive about 1 kW of power from light, and the microbrain somehow absorbs and uses all of that energy to produce mass, it would take about 9 x 10⁹ seconds, or about 285 years to produce 1g of mass. This is a long time.

Albert Einstein, father of relativity and E = mc² (Source)

If, however, the power that was being diverted from the enterprise was being used to fuel the growth of the microbrain, I can understand that. Except then it wouldn't have started dying when they dimmed the lights in the room...

So there were small contradictions in the episode, but I thought the underlying question about the nature of intelligent life was very thought-provoking. I wonder if there can be intelligent inorganic life out there. And if there is, would we even be able to recognize it?

Star Trek: Aldea and the Physics of Invisibility

2012-07-13T18:14:00.000-07:00

Star Trek the Next Generation (1987-1994) (Picture)
Season 1, Episode 16
When the Bough Breaks

At the start of episode 16, the Enterprise stumbles upon the mythical planet Aldea, which has been said to possess a cloaking device and other advanced technology. The cloaking device is intriguing and I am going to explore the possibility of the technology ever existing.

What does it mean to see something, anyway?

As a very basic explanation, the human eye and brain "see" electromagnetic radiation in the visible range of the electromagnetic spectrum. All electromagnetic waves are called photons and these photons can have different frequencies (and therefore energies) depending on where they fall in the electromagnetic spectrum.

A diagram of the electromagnetic spectrum (Source)

The above diagram shows the electromagnetic spectrum. The range of frequencies humans can see are shown as the visible range. In order to make an invisibility cloaking device that tricks humans the photons in this range need to be bent around the planet Aldea.

How do you bend Electromagnetic Waves (Photons)?

The bending of electromagnetic waves is called refraction. In Star Trek the cloaking device the planet used was described as an electromagnetic shield, a complicated light refracting mechanism.

So far, so good. Star Trek is right in saying that an invisibility device would need to refract electromagnetic waves around the planet to make it appear as though it is not there.

A common way of bending electromagnetic waves is by using a waveguide. Waveguides internally reflect the electromagnetic waves to get them from point A to point B.

A diagram of a waveguide (optical fiber in this case). (Source)

Note in the above diagram that the incoming waves (from the left) bounce around within the waveguide and do not exit until they reach the other end. This is what a waveguide does. By reflecting the waves completely inside they are able to pass them from one end to another. Waveguides do not need to be straight, like in the diagram: they can bend and curve, as well.

By utilizing some form of waveguide it is possible to bend waves. Depending on the material used it can be done with any wavelength of electromagnetic radiation, as far as I know.

Ok, but how could the Aldeans cloak an entire planet?

This I do not know. There has been research done to try to make an invisibility cloak. What I have found suggests that there is now a suit that can bend microwaves (long wavelength electromagnetic radiation - near left side of the above spectrum) around a person. There is a short video explaining this here.

A look at how an invisibility cloak might work. (Source)

This method would make a person invisible if we saw things in the microwave part of the spectrum. Since we see things in the visual, or optical, part of the electromagnetic spectrum, this does invisibility cloak would not make us invisible to one another.

Using this method the Aldeans would have to surround their entire planet in a physical material, which seems impractical. This cannot be how they solved the problem, given that they are able to turn it on and off whenever they want.

In the episode it was proposed that an electromagnetic field was responsible for bending the light around the planet.

Other Issues...

In addition to cloaking electromagnetic radiation in the visible range, the Aldeans would have had to reflect other wavelengths of the spectrum as well. I am sure there are species in Star Trek that do not see purely in the visible range. On earth, for example, bees are well known to see a different range of electromagnetic frequencies.

This shows the different frequencies that humans and bees see. (Source)

Bees see into the ultraviolet part of the spectrum and see much less of the lower energy optical wavelengths we associate with the color red.

Sorry for the tangent about bees - what I wanted to bring up is the fact that different species see different parts of the spectrum, so the cloak used by the Aldeans would have to refract a very large range of frequencies (maybe all of them). This is well beyond current technological capabilities.

Star Trek Physics: The Bynars

2012-07-11T13:00:00.003-07:00

Star Trek the Next Generation (1987-1994) (Picture)
Season 1, Episode 14
11001001

The bynars, an alien species that live and work in pairs, board the Enterprise at Starbase 74 to perform some repairs and upgrades to the computer systems. These creatures live symbiotically with computers and have a language and way of thinking that is linked strongly to binary. Binary is the most basic level of computer programming - all higher level programs are eventually understood by the computer as a combination of 0's and 1's. In this post I'm going to muse on the possibility of a species like the binars existing someday.

Symbiosis
This is a tantalizing question and I don't have a clear cut answer. The relationship between the living part of the bynars and the computer part can be viewed as a symbiosis. There are three generally accepted forms of symbiosis:

Mutualism - two organisms of different species interact in a way that benefits both
E.g. Clownfish and sea anemone. The anemone protects the clownfish from predators and the clownfish fertalizes the anemone with its waste.

Clownfish and a sea anemone, an example of mutualism (Source)

Commensalism - two organisms of different species interact in a way that benefits one and is neutral to the other
E.g. Barnacles on a scallop. The barnacles benefit by having a hard substrate on which to attach itself, while the scallop is unaffected.

Parasitism - two organisms of different species interact such that one benefits at the expense of the other
E.g. Mosquitoes. They suck blood to spawn new baby mosquitoes and we lose blood and can get passed diseases.

The biological/computer components do not fit neatly into any of these classifications. I'm going to say that relationship is not exactly symbiosis, because symbiosis is between two different species. In this case it would be strange to think of computers as being a species. Still, I think the types of symbiosis are useful in describing the relationship between the biological and computer sides of the binars.

The relationship is clearly not parasitic, because one does not harm the other. Arguments could be made for either mutualism or commensalism. The argument for mutualism would be that the binars benefit because they can store and process incredible amounts of data and can basically talk to computers, while the computers have access to lots of data and are maybe "better cared for" because they have a species that is built to understand them. On the other hand, if computers are believed to not be capable of having an opinion, the relationship seems commensal because the binars benefit from the relationship but the computers don't really care.

What complicates this in my mind is that during the episode the bynars were dying because their computer system was in jeopardy. This means that they rely on the computers for life. This seems like a bad configuration - without the biological components, the computers are screwed and vice versa. My belief is that a relationship like that would not really develop in nature. Even in the clownfish/anenome example one can live without the other, though their chances of survival might be lower without one another.

So Could the Binars Exist?

I think ultimately the existence of beings like the bynars that are integrally bound to computers is possible under the following conditions: their dependence on computers will have to come from them being derived from a being that was not initially dependent on computers. There must have been some selection pressure on the beings that required them to use technology to survive. In this way, the newly born beings would be unable to survive without the technology. In this sense, they are not born with computer parts in them but would need to couple themselves to computers after birth in order to survive.

The coupling is a slippery slope, but i think it can be done in some capacity. Let's look at an example: today there are people who require pacemakers or prosthetic limbs, so there is a precedent for people living with mechanical parts. We are also able to send electrical signals to the brain and measure responses. People who were previously completely blind can now "see" to an extent with technology. The same goes for people who could not hear before and now have a kind of "hearing".

Now imagine a selection pressure on the population that results in only people with genetic blindness or another specific disability surviving. The result could be that every person on earth requires computers or other machines for "sight." The same sort of process could have occurred to the bynars, making them reliant on the computers for life. How they rely on them for life I am not sure, but the concept of having an entire species dependent on computers for survival is not too farfetched. It certainly inspires the imagination. Thoughts?

The Physics of Jurassic Park (1993)

2012-07-08T16:03:00.000-07:00

SPOILER ALERT! Plot details from Jurassic Park (1993)
(Reference for image at left)

Jurassic Park is one of my favorite science fiction movies. Every boy has a dinosaur phase while growing up and I never quite outgrew mine. The thought of using science to populate an island with dinosaurs is mind bogglingly awesome. In the post after the jump I analyze the possibility of cloning dinosaurs from ancient mosquito blood, the scientific precedent for asexual reproduction in reptiles, and more...

Cloning Dinosaurs from DNA found in Mosquito Blood

Overview
Geneticists on the Jurassic Park island grow the population of dinosaurs by using dinosaur DNA trapped in amber from millions of years ago to clone new dinosaurs.

Realistic or unrealistic?
Unrealistic

Close but no cigar with this one. It is possible to clone animals using DNA samples and DNA can be found in blood. However, the blood in the mosquitos would decompose starting when they died. After millions of years there would be no recoverable DNA in the sample.

Asexual Reproduction

Overview
On the Jurassic Park island dinosaurs are allowed to roam free. Their population is limited because the scientists that cloned them from DNA found in the blood of mosquitos trapped in amber filled the island with only female dinosaurs. Therefore, there can be no reproduction, right?

Realistic or unrealistic?
Realistic!

It would be comfortable to think that they were right and the dinosaurs could not reproduce. However, as the mathematician and chaos expert says during the movie, "Life finds a way." It turns out this is pretty true. There have been documented examples of reptiles such as Komodo dragons reproducing asexually when they cannot find a suitable mate. So I would say Jurassic Park has good science there: it is possible.

A hatching Komodo dragon (Reference)

The Physics of Iron Man (2008) and Iron Man 2 (2010)

2012-07-08T13:36:00.000-07:00

SPOILER ALERT! Details about Iron Man (2008) and Iron Man 2 (2010) below

Iron Man and Iron Man 2 contain many fantastic scifi elements, including the arc reactor, chemical poisoning, and creating new elements using particle beams. In this post I investigate the scientific basis of these technologies and biological effects. For example: Is it possible to make an arc reactor? Yes and no! I explain more after the jump.

The Arc Reactor

Overview
When Tony Stark goes to Afghanistan to give a weapons demonstration he is wounded and captured. His captors put him in a cave and demand that he build them a missile. While in the cave he builds what he calls an "arc reactor" that provides power to his body and prevents the shrapnel in his chest from inching closer to his heart.

To clarify something, when he says "arc reactor" he really means mini fusion reactor. An arc reactor is another scientific device that I believe is used in the doping of metals and is used in the production of bucykballs. Buckyballs are super cool spherical molecules made from 60 carbon atoms. They're the largest molecules that have been shown to exhibit wave-particle duality. Anyway, back to Iron Man...

Tony Stark with the arc reactor embedded in his chest

Realistic because:

Fusion is a real source of energy. In the sun's core Hydrogen atoms fuse together to produce Helium and release energy. This is eventually received by the earth in the form of solar energy.

A diagram of the fusion process

We have achieved fusion on earth in tokamak devices. These are donut-shaped nuclear fusion reactors. Tony Stark's "arc reactor" shape is consistent with the shape used to achieve fusion in research reactors around the world.

Unrealistic because:

The "arc reactor" could not be as small as Tony Stark makes it. Current models of fusion plasmas tell physicists that sustained fusion should be achievable if we scale up the size of the reactor. In France ITER (International Thermonuclear Experimental Reactor) is being built. A diagram of ITER is shown below. The physics of scaling something like a fusion reactor down to the size of something that can be fit into a person's hand is presently unfathomable. For more information, see the Lawson Criterion.
Magnetically confined fusion required very powerful magnets. These magnets have to be cooled to extremely low temperatures, about -200 degrees Celsius or -328 degrees Fahrenheit. It would be impossible for Tony Stark to keep the magnets cold and keep himself at body temperature.
The magnets produce very high magnetic fields. This means that the shrapnel would be ripped right out of his body.
He would need to have a source of Deuterium and maybe Tritium. Deuterium-Tritium fusion, shown in the fusion image above, is the most easily attainable form of fusion. There are only a few small supplies of Tritium in the world, so it would be nearly impossible for him to get a source in a cave... Also, Deuterium is found naturally occurring in water with about 1 in 3200 water molecules containing Deuterium, but Tony would need a method of separating the Deuterium from the rest of the water. This is not a trivial process.

Palladium Poisoning

Overview
In Iron Man 2 Tony gets palladium poisoning and needs to find a replacement element for his arc reactor.

Realistic because:

Palladium poisoning actually occurs
Old fusion reactor designs did often use palladium

Unrealistic because:

Present fusion reactor designs do not use much palladium
The symptoms of palladium poisoning are a little different than exhibited in the movie. While difficulty breathing, wheezing, and a cough are all symptoms the raised veins or raised dark lines on Tony's skin are not how it manifests. It typically looks like a bad red rash, with hives all over the skin.

Creating New Elements with Particle Beams

Overview
In Iron Man 2 when the palladium poisoning begins to compromise Tony’s health, he searches for an element that can take its place in the arc reactor.

Realistic because:

It is possible for Tony Stark to discover a new element by using a particle beam. This is how many man-made elements were discovered.
There could theoretically be an “island of stability” of elements heavier than presently known, though it is unlikely. Most heavy elements are very unstable, decaying to other elements almost instantly.

Unrealistic because:

It’s unlikely that there is a stable element with mass larger than those that have currently been discovered. If he were to synthesize a new element by bombarding a material with a particle beam then it is almost guaranteed to be extremely unstable, meaning that by the time he could check to see what it is it would have decayed to another element.
The particle beam would almost certainly not be visible, like it is in the movie.
The beam would not cut through the materials in his lab. The density of particles in the beam would not be great enough to cut through the metal structures in his lab. Particle beams aim to have the particles in the beam absorbed by the nucleus of the targeted material so as to create new elements, or to understand known elements.

Other good blogs about the physics behind Iron Man:

http://scienceblogs.com/builtonfacts/2010/04/29/physics-rockets-and-iron-man/

http://popwatch.ew.com/2010/05/11/iron-man-2-science/

http://blogs.discovermagazine.com/80beats/2010/05/07/iron-man-2s-science-tech-are-grounded-in-reality—mostly/ Iron Man 2 Stark Expo Play Set By Mega Bloks (Google Affiliate Ad)