“Schrodinger’s Cat” was not a real experiment and therefore did not scientifically prove anything. Schrodinger’s Cat is not even part of any scientific theory. Schrodinger’s Cat was simply a teaching tool that Schrodinger used to illustrate how some people were misinterpreting quantum theory. Schrodinger constructed his imaginary experiment with the cat to demonstrate that simple misinterpretations of quantum theory can lead to absurd results which do not match the real world. Unfortunately, many popularizers of science in our day have embraced the absurdity of Schrodinger’s Cat and claim that this is how the world really works.
In quantum theory, quantum particles can exist in a superposition of states at the same time and collapse down to a single state upon interaction with other particles. Some scientists at the time that quantum theory was being developed (1930’s) drifted from science into the realm of philosophy and stated that quantum particles only collapse to a single state when viewed by a conscious observer. Schrodinger found this concept absurd and devised his thought experiment to make plain the absurd yet logical outcome of such claims.
In Schrodinger’s imaginary experiment, you place a cat in a box with a tiny bit of radioactive substance. When the radioactive substance decays, it triggers a Geiger counter which causes a poison or explosion to be released that kills the cat. Now, the decay of the radioactive substance is governed by the laws of quantum mechanics. This means that the atom starts in a combined state of “going to decay” and “not going to decay”. If we apply the observer-driven idea to this case, there is no conscious observer present (everything is in a sealed box), so the whole system stays as a combination of the two possibilities. The cat ends up both dead and alive at the same time. Because the existence of a cat that is both dead and alive at the same time is absurd and does not happen in the real world, this thought experiment shows that wavefunction collapses are not just driven by conscious observers.
Imagine a 4-dimensional object… Unfortunately, you soon realize that you can’t. But why? Our brains are not hardwired to picture anything beyond 3 dimensions. Life on Earth only goes until the 3rd dimension. The human brain cannot imagine something that it has never been exposed to (such as the 4th dimension). It would be like envisioning a new color out there in the universe that has not yet been discovered by humans. How would you describe it? The inexplicable nature of this mathematical and physical concept makes it a true wonder of physics. However, many theoretical physicists have proposed several theories as to what the 4th dimension is and what it would look like. Scientifically, we can describe this dimension but we may never experience it in the physical realm.
Before we delve into the details of the 4 dimensions, we need to understand what the first few dimensions are. To begin, take a point that has no spatial extent – we’ll say this is a 0-D space. Stretching this point out creates the first dimension which is a straight line with 0 width and only length. You can only travel in 2 ways – forwards or backward. 2-D space is a stack of infinite 1-D space spread out lengthwise or breadthwise. An example of a 2-D shape would be a square. There are more ways by which one can travel in 2 dimensions – forwards, backward, left, and right. 3-D space is in fact an infinite heap of 2-D space stacked upon each other. In 3-D space, there are three coordinate axes—usually labeled x, y, and z—with each axis orthogonal (i.e. perpendicular) to the other two. The six directions in this space are called: up, down, left, right, forwards, and backward. Lengths measured along these axes can be called length, breadth, and height.
Many physicists, including Einstein as part of his ‘Special Theory of Relativity, proposed that the fourth dimension is time. He said time should be a dimension like the other spatial dimensions because space and time are inseparable. If you wish to move through space, you cannot do it instantaneously; you have to move from where you are right now to another spatial location, where you’ll only arrive at a certain point in the future. If you’re here now, you cannot be in a different place at this same moment, you can only get there later. Moving through space necessitates you to move through time as well. Hence, they argue that time is the 4th dimension since, without it, we cannot construct any meaningful position vector with an unchanging length. Time’s dimension is a line going from the past to the present to the future. Thus, time as the fourth dimension locates an object’s position at a particular moment. If we had the ability to see an object’s fourth-dimensional space-time (or world-line) it would resemble a spaghetti-like line stretching from the past to the future showing the spatial location of the object at every moment in time. Unlike the other spatial dimensions, we can only move forwards in time. The other dimensions allow you to move both ways. Hence, they separate time from spatial dimensions and call it a temporal dimension. On the other hand, some researchers, using the logic of other dimensions, still hold out hope for finding wormholes in the universe that connect to different sections of space-time (i.e. the past).
Dr. Michio Kaku is the co-founder of string field theory and is one of the most widely recognized scientists in the world today. He has written 4 New York Times Best Sellers, is the science correspondent for CBS This Morning, and has hosted numerous science specials for BBC-TV, the Discovery/Science Channel. His radio show broadcasts to 100 radio stations every week. Dr. Kaku holds the Henry Semat Chair and Professorship in theoretical physics at the City College of New York (CUNY), where he has taught for over 25 years. He has also been a visiting professor at the Institute for Advanced Study as well as New York University (NYU).
In a profoundly informative and deeply optimistic discussion, Professor Michio Kaku delivers a glimpse of where science will take us in the next hundred years, as warp drives, teleportation, inter-dimensional wormholes, and even time travel converge with our scientific understanding of physical reality. While firing up our imaginations about the future, he also presents a succinct history of physics to the present.
To many people, antimatter probably sounds a lot stranger than it really is. In its most basic sense, antimatter is just mattered with its electrical charge reversed. However, upon meeting, matter and antimatter annihilate one another in a flash of energy.
So what about antimatter bombs?
It seems simple, really. Introduce antimatter to matter and wait for the “BOOM” (of course, with your hands over your ears and your goggles secured firmly to your face…safety first!). But, is building an antimatter bomb realistically viable?
In the Star Trek episode “Obsession,” one ounce of antimatter reacting with matter is enough to blow up half an atmosphere of an Earth-sized planet. So as Landua’s commentary illustrates, unsurprisingly, an antimatter bomb isn’t as spectacular as science fiction makes it seem. For comparison, one pound of antimatter is equivalent to around 19 megatons of TNT. So yes, antimatter would be stronger than other explosives, but not quite as catastrophic as some sources indicate.
Even if it were possible to produce antimatter at a faster rate, the cost would be enormous. According to Landua, a gram of antimatter would cost approximately a “million billion dollars.”
Wormholes were first theorized in 1916, though that wasn’t what they were called at the time. While reviewing another physicist’s solution to the equations in Albert Einstein’s theory of general relativity, Austrian physicist Ludwig Flamm realized another solution was possible. He described a “white hole,” a theoretical time reversal of a black hole. Entrances to both black and white holes could be connected by a space-time conduit.
In 1935, Einstein and physicist Nathan Rosen used the theory of general relativity to elaborate on the idea, proposing the existence of “bridges” through space-time. These bridges connect two different points in space-time, theoretically creating a shortcut that could reduce travel time and distance. The shortcuts came to be called Einstein-Rosen bridges, or wormholes.
What is antimatter? What happens if matter and antimatter interact? How was antimatter discovered? Why don’t we usually come across antimatter in our daily lives? All these questions and many more come to one’s mind when thinking about antimatter. But, first things first! Let us first define and understand what antimatter is.
Antimatter is the opposite of matter, literally. For every sub-atomic particle, such as an electron, a proton, a neutron, etc. there exists an antiparticle such as an anti-electron, anti-proton, and anti-neutron. The antiparticle will have the same mass as the particle, but it will differ in the sign of its charge and other quantum numbers. Some of these quantum numbers are the lepton number – one for the electron and each of the other five members of the lepton family, and the baryon number – one-third for each of the six quarks that make up the baryon family. Antiparticles are expected to interact with other antiparticles in exactly the same way ordinary particles interact with each other. The laws of physics are (almost) symmetric when it comes to matter and antimatter. In fact, a Universe made up of antimatter would be indistinguishable from ours!
Going into a little bit more detail, the anti-electron is called a positron (for positive electron) and it is positively charged with a lepton number of minus 1. The positron has exactly the same mass as the proton. The proton is a positively charged sub-atomic particle made up of three quarks giving it a baryon number of one. Its antiparticle, the antiproton, has the same mass as the proton but it is negatively charged with a baryon number of minus one (minus one-third contributed from each of the three antiquarks that make up the antiproton). Neutral sub-atomic particles, such as neutrons, are interesting. The antineutron has the same mass and zero charge as the neutron, but it will have a baryon number of minus one (again, minus one-third coming from each of the three antiquarks that make up the antineutron).
So what happens when matter and antimatter interact? The answer is fireworks! When a positron interacts with an electron they both annihilate to produce two X-ray energy photons! So, we are in luck that antimatter is so scarce in the Universe nowadays. Otherwise, we would have been burned by X-rays and gamma-rays every time matter and antimatter interacted. As a matter of fact, if you were to meet your anti-self then both of you would annihilate and release the equivalent energy of roughly 2500 megatons, almost one-third the total energy of the world’s arsenal of nuclear weapons! Antimatter could sure make for mighty powerful spaceship engines IF you can find a way to produce macroscopic amounts of antimatter AND a way to store it in isolation! Some modern particle accelerators regularly produce antiprotons for use in high-energy physics experiments.
Now that we know what antimatter is, let us see how physicists discovered it. Back in the year 1928, Paul Dirac, one of the founding fathers of the new science of quantum mechanics, was trying to solve an equation that included the effects of the theory of special relativity to describe the behavior of electrons in the microscopic world. To his surprise, the equation admitted solutions that corresponded to electrons with negative energy going back in time! Any insecure student of physics would have blushed with embarrassment and redid the math. However, Dirac was sure of his math. Instead, he reinterpreted his problematic solution to denote an “anti-electron” with positive energy going forward in time. Four years later, an experimental physicist by the name of Carl Anderson proved Dirac right by actually observing the anti-electron, the positron. The discovery of the positron earned Anderson the Nobel Prize in 1936. Dirac had already won the Nobel in 1933 for his contributions to atomic physics. Are you wondering where Anderson’s positrons came from? The positrons that Anderson discovered originated in atmospheric showers of sub-atomic particles that result when very high-energy cosmic rays (mostly protons) interact with atoms in Earth’s atmosphere.
The story of the prediction and subsequent discovery of the positron is instructive and shows how big discoveries in physics are often made. The device used by Anderson is called a cloud chamber and was a standard instrument used in nuclear physics labs at the time. A particle going through a cloud chamber would leave a sort of a trail of bubbles in its wake. Applying a known magnetic field would curve the particle according to its charge.