Monthly Archives: September 2012

You board the CATA bus and it pulls away immediately as you walk towards the back to take a seat. The bus is moving at 25 mph as you walk at about 3 mph. Your speed relative to someone standing outside of the bus is only 22 mph. As your stop approaches you get out of your seat to move to the front. Now your speed relative to someone watching from the sidewalk is 28 mph since your walking speed of 3 mph is added to the bus’s 25 mph. Now instead of a CATA bus, let’s imagine that you are on a spacecraft that can travel at speeds approaching the speed of light.

Since most of us hate the metric system, we’ll stick with English units. The speed of light is 670 616 629 miles per hour. Since it is impossible to travel exactly that fast (you can travel 99.999% that speed but never reach it according to Einstein), we’ll be traveling on our spacecraft at only a couple miles per hour slower, 670 616 620 miles per hour. Now, since intergalactic travel is long and boring, the spacecraft has a gym, basketball court, and track for you to stay in shape. At the end of another uneventful day, you decide to go work out. Sprints seem like they’d be fun. You head to the track and do your sprints. You’re a pretty good sprinter so you peak at 14 miles per hour. All of this seems practical until you analyze the system from outside of the ship, as we did with the CATA bus. If you are sprinting in the direction opposite of the spacecraft’s motion, your relative speed is then 670 616 606 mph, which poses no problem. It is when you turn around and sprint back that everything falls apart. Adding the speed of the ship to your sprinting speed, you would be moving, relative to a stationary point outside of the ship, at 670 616 634 miles per hour…five miles per hours over the speed of light.

The speed of light is the intergalactic speed limit, so obviously something is terribly wrong with the above situation (other than the fact that you’re doing sprints on an intergalactic spacecraft moving at nearly the speed of light). The reason that you would not break the speed of light is because of time. Time is relative, as Einstein so brilliantly theorized. This means that time depends on those experiencing it. This is a very confusing topic but I’ll try to put it in perspective.

Everyone experiences time in the same way. As you are traveling through space close to the speed of light, time goes by as usual. A day feels like a day, a year like a year. While you’re on your trip, I am still back on Earth, where time carries on as usual. Everyday feels the same, every year the same as well. It is not until your return that we learn how time has changed between the two of us. Your trip was only a year long for you, but you find that decades have passed here on Earth while you were gone. This is because time slows down as you approach the speed of light, and it is because of this dilation of time that you do not break the intergalactic speed limit. While, from your perspective, you are sprinting at 14 mph, time is actually traveling a thousand times faster than it seems to you. The sprints only take a couple seconds from your perspective, but, from the perspective of time here on Earth, it takes you days to do one sprint; you may think that you are fast, but to us it would barely look like you’re even moving. It is this time compensation that prevents you from breaking the speed of light.

But does this make intergalactic travel impossible. Even if we could build such a spacecraft, even if it traveled at speeds hundreds of thousands of miles per hour less than the speed of light (still unfathomably fast), time would mess everything up. A trip to the nearby stars or even the center of the Milky Way would definitely be plausible with this kind of ship. Astronauts would reach the center of the galaxy in twenty some years – in their time. Upon returning to Earth after their 50 year round trip, somewhere in the tens of thousands of years would have passed on Earth. In the future, we may be able to develop ways to overcome the difficulties of building spacecraft to travel at the breakneck speeds approaching the speed of light, but we may never overcome the universe’s laws of time.

In the world of physics, neutrinos are still in their infant years. It was just in 1930 that Wolfgang Pauli even hypothesized the existence of such a particle. It was named years later, and still not experimentally observed until 1959. Although it has been over fifty years since its discovery, neutrinos are still surrounded by an air of mysteriousness.

Neutrinos are subatomic particles with no charge and essentially zero mass. Many physicists postulate that the particle has some mass, only very minuscule, even compared to other subatomic particles. Most tests results have just been stated to be “consistent with zero mass for neutrinos.” This theory has neither been proved nor disproved, although more and more scientists are leaning towards the theory that they do have mass because slowly but surely tests are collecting evidence that points towards this result.

The process of trying to determine the mass that might exist has been long and tiresome because of the nature of neutrinos. With such little mass (if any), they do not interact with matter. In fact, they go right through it. Neutrinos are constantly being produced by the nuclear reactions within the sun, therefore there is a continuous flow of neutrinos through the earth and everything on it,  including us. Only one in about a billion parts reacts with matter. To try to detect these scientists have been developing a neutrino telescope; the word telescope is loosely used because it is more of detector in this case than a telescope. It was discovered that large amount of neutrinos react with chlorine nuclei to produce argon. Using enormous vats of perchloroethylene, physicist can measure neutrinos by correlating it to the argon produced, which is only a handful every month.

But whats the big deal? Why does it matter if these neutrinos have an extremely minimal amount of mass or no mass at all?

The truth is that it makes all the difference. The mass of neutrinos can help solidify the Big Bang Theory as well as quantum and string theories. The beginning of our universe as well as its demise could be better predicted once we know the mass of neutrinos.

Our universe began with the Big Bang. This is a widely accepted theory because of all of the evidence that has been found to support it. It is not complete though. It theorizes that at the instance of the Big Bang, all of the mass of the universe was created, but it was created in the form of matter as well as antimatter. What is not known is what caused matter to prevail over antimatter in its fight for existence. This is where neutrinos may come in, along with their counterpart, the anti-neutrinos. Theorists believe that the abundance of neutrinos that were created during the waking seconds of our universe may have been great enough to help matter prevail over antimatter. If this is the case, neutrinos are the reason the universe did not just collapse immediately into nothing immediately after the Big Bang due to the reaction of equal amounts of antimatter and matter. You may think that a particle that has such little mass, essentially no mass, could not possibly have such a great impact, but the truth is that after the Big Bang it is approximated that there was only one extra particle of matter for every billion particles of antimatter, i.e. one billion particles of matter reacted with one billion particles of antimatter and leave just one measly particle of matter left over. Yet this was enough to create the universe we know today.

The end is even more so theoretical than the beginning. While there is evidence supporting the Big Bang, no such evidence could exist for the future. The two main theories about the end of our universe are the Big Crunch and the slow eternal expansion of everything. Both are highly dependent on gravity. Scientists have been researching ways to measure the entire mass of the universe. If the mass is great enough, the force of gravity will eventually cause the universe to stop expanding, turn around, and begin to contract. This is the Big Crunch Theory. It revolves around the belief that our universe is cyclical in nature. As gravity pulls the universe together into a single point, temperatures increase to unimaginable levels as suns combine and swallow planets and everything collapses into a single point. All matter would then be converted into its original form of energy, so much energy that it would explode into another Big Bang, creating a whole new universe. On the other hand, if the mass of the universe was not large enough for gravity to take control, everything would expand into eternity. The night sky would slowly become barren as stars become so distant that their light no longer reaches us. Our planet would then only exist until our sun dies; our universe would exist until it exhausts itself in a slow painful death. We don’t know which theory is true, but we know that it depends solely of gravity, and thus on the mass of universe. The missing mass that could eventually bring our universe back together into the Big Crunch could be found in neutrinos – one particle, invisible even on the subatomic level, determining the fate of everything.

I am hoping that you have all heard of CERN, the large hadron collider whose headquarters are in Geneva, Switzerland. If you have not heard of it, it is basically the largest testing facility for particle physics, and is home to the largest particle accelerator in the world. Physicists use the machine, a huge ring of tubing with a 27 km circumference, to collide particles in order to study the composition of subatomic particles, string and quantum theories, and the effects of gravity at such  a nanoscopic level.

If you have heard of CERN, you may have also heard about so-thought breaking of the speed of light. Just a year ago, in September of 2011, physicists at CERN were experimenting with neutrinos, sending them from the laboratory in Geneva to Gran Sasso laboratory in Italy.

You may be confused right now by the word neutrinos. They bring up a whole new story, which I will discuss in my next blog post, but for now you just need to know what they are, not their entire possible impact on the universe. Neutrinos are subatomic particles released during nuclear reactions like those of the sun. These particles have no charge, and are absolutely minuscule, even compared to the rest of the subatomic world. In fact, they are so small that scientists have yet to determine their mass. Also, their tiny nature allows them to move right through matter; with almost no mass and extremely weak electromagnetic interaction forces, matter has essentially zero effect on it.

The physicists used GPS systems and other devices to time the flight of the neutrinos, a flight that, although over 450 miles long, take about one five-hundredth of a second; to put this in perspective, it is equivalent to traveling from here at State College to Boston in 1/30th the time it takes for you to blink. All the measurements for all the parameters of this experiment were extremely precise. As they say in the CERN press release, “The distance between the origin of the neutrino beam and OPERA was measured with an uncertainty of 20 cm over the 730 km travel path. The neutrinos’ time of flight was determined with an accuracy of less than 10 nanoseconds by using sophisticated instruments including advanced GPS systems and atomic clocks.”

Even with all the research and preparation that had been done, physicist were extremely surprised to find their results showed that the neutrinos travel faster than light. The press release from CERN is linked at the bottom of this page, if you would like to read more. It included press releases from about the event for months following this “discovery,” as scientists did thousands of test to accomplish one of two things: gain more experimental results backing up the data, or find the fault in the original experiment which would prove the results wrong. In the end, they found that some of the measuring equipment was malfunctioning – although in this case a measurement could have been off by mere nanoseconds and have caused appalling results.

If this experiment had actually yielded legitimate results, the world of physics would have been drastically changed. Breaking the speed limit is not something taken lightly in the physics world. It would contradict Einstein’s theory of relativity, the set of ideas that essentially all of modern physics is based off of. It would force physicist to create new theories because all of the modern physics theories, including Quantum theory, String theory, and other subatomic anomalies, would all be garbage… but that also, will be a discussion for another day.

http://press.web.cern.ch/press/PressReleases/Releases2011/PR19.11E.html

How do planes fly?

This seems like a pretty easy question. We’ve all learned the basics of lift based on Bernoulli’s Principle. The curved shape of the wing causes the air above the wing to travel over a further distance than the air below the wing. Since the air above the wing travels a further distance in the same time, it has a higher velocity. According to Bernoulli’s principle, the change in velocity from the top to the bottom of the wing causes a change in pressure. The higher velocity causes a lower pressure. The higher pressure on the bottom causes the lift.

There is one very huge misconception here: that the air over the top and the bottom of the wing take the same amount of time to travel from tip to tail. Experiments using wind tunnels and dye have proven that the air above the wing has a longer travel time than that below the wing. The second fallacy about this generally accepted theory is the math behind the lift. Planes would have to have extremely bulbous wings in order to produce enough lift, i.e. the top portion of the wing would have to be close to twice as long as the bottom. Bernoulli’s Principle is generally accepted because it is easier to understand than the truth.

The truth comes from Newton’s Laws – somehow Newton just got everything right. His third law is the true explanation of how planes fly. The wings of a plane force air down – enough air is forced down to cause an equal and opposite reaction strong enough to lift the plane. The reason huge masses of air can be forced down is because of fluid viscosity. As air is pulled over the wing, it clings to the wing – in the same way that water clings to your finger under a faucet and deflects the stream – and as it is pulled downward, the attraction with other air molecules pulls more air down. This causes a cycle like the picture to the below.