With this blog I just wanted highlight Jacqui Murray’s reblog of my Science for Babies Post. I would like for you to head over to Ask A Tech Teacher and check out her post. Also thank you very much Jacqui for your kind repost.
Category: Physics
Important but surprising or strange facts relating to Physics
Superfluid Liquids are Like Magic
Super fact 60 : Superfluids such as liquid Helium cooled below -455.58 Fahrenheit exhibit some very strange characteristics such as it flows right through many solids, it climbs walls, it has near zero viscosity, it exhibits circulating flows that never stop despite no energy being added. It is a Macroscopic Quantum Phenomenon.
When gases are cooled far enough, they will turn into liquids and eventually typically to solids. For example, Oxygen becomes a liquid when its temperature drops to -297 Fahrenheit, which is -183 Celsius, or 90 degrees Kelvin. Kelvin is 0 at absolute zero, the coldest possible temperature, and in addition it uses Celsius for the scale. So, 90 degrees Kelvin is 90 degrees Celsius above absolute zero or 162 degrees Fahrenheit above absolute zero. When Oxygen becomes a liquid, it turns into a pale blue liquid. Oxygen becomes a solid at 54 Kelvin, or −218.8 Celsius, and −361.8 Fahrenheit (at normal pressure). It becomes sky blue ice.
Helium stays a gas until very extreme temperatures. Helium becomes a liquid at 4.2 kelvin or -269 Celsius, or -452.11 Fahrenheit. If the temperature is reduced further by almost half to 2.17 Kelvin, or -270.98 Celsius, or -455.8 Fahrenheit, then Helium suddenly becomes a superfluid, exhibiting macroscopic quantum phenomena. It is so different from normal liquid Helium that it is called Helium II. Its heat conductivity (speed of heat/cold transfer) suddenly increases by one million, and the temperature will become the same throughout the liquid instantly. Even a big pool of liquid helium would almost instantly get the same temperature throughout, and the atoms will start behaving in unison. Regular bubbles can no longer exist (atom sized electron bubbles can exist though).
The liquid starts behaving in bizarre ways. If you place an open metal container of Helium II in a closed room the Helium II would climb out of the container and escape, and a thin film of Helium II would climb the walls and the ceiling. If the floor was made of metal or glazed tile the Helium II would remain on the floor. If the floor was made of unglazed tile or stone, it would leak right through the floor as if the floor was a sieve. If you get a whirlpool or fountain going it will keep going forever without any energy loss. In addition, it would also exhibit many quantum effects that are out of scope for this post.
I consider this a super fact because this is a strange, surprising and not a well-known phenomenon. It is a quantum effect that you can observe with your own eyes. It is important because the discovery of superfluidity and its twin effect superconductivity are very important for science and might lead to revolutionizing energy transport in the future. It is no doubt that the phenomenon is real (true), and it has been documented by numerous experiments and papers. It is described in thousands of textbooks, and I’ve observed the phenomenon with my own eyes (that is next).
Our Experiment with Superfluid Helium
During my first class in Quantum Physics, we performed experiments with liquid Helium. We started out by cooling helium using liquid nitrogen (colder than -196 Celsius or -321 Fahrenheit). Then using vacuum pumps, we kept cooling the Helium until it became liquid. We continued cooling it and we could see lots of bubbles and boiling as we kept going, and then it boiled extra much, and then very quickly the bubbles vanished, and the content of the entire glass container settled down and then stood perfectly still.
As 2.17 Kelvin was reached the viscosity (flow resistance) was instantly lowered with about one million times, and non-microscopic bubbles could no longer exist. The heat conductivity (the speed with which temperature spreads) increased by one million times. It means that the heat of a drop falling in one end of a swimming pool of Helium II would spread throughout the swimming pool in a second. Except, we only had a glass container in which sameness reigned throughout the liquid.
We continued doing experiments such as watching the Helium II climb walls inside the experimental setup, and of course the famous fountain. Insert a little metallic straw and watch a Helium fountain start to flow, by itself. Without any energy or pressure added, it just kept going by itself because no energy was lost either.
I can add that it was more of a demonstration than an experiment that we actively participated in because playing with extreme temperatures high or low is dangerous. If you’ve read this blog for a while you might remember when I put a Cesium-137 sample (800 times more radioactive than Plutonium-239) in my jeans pocket instead of back into its lead brick container and walked around with it a whole day. Or that time when I replaced a fuse for a 380 volt three phase powered laser with my finger because I was curious what would happen if I put my finger in there, and I was shocked, and it hurt. Students shouldn’t play with dangerous stuff.
Below is a one minute and forty four second YouTube video of a Superfluid / Helium II experiment showing an eternal fountain.
Below is a four minute explanation of a superfluid / Helium II experiment.
I can add that Helium II (super cold helium) is not the only superfluid but the easiest one to achieve.
Other Physics Related Superfacts
- Some Things Cannot be Known
- Radon Represents our Largest Exposure to Ionizing Radiation
- We are Star Dust
- The Speed of Light In Vacuum Is a Universal Constant
- Two events may be simultaneous for some but not for others
- The Strange Worlds of Exoplanets
- The vastness of space and the beginning of infinity
- The Bizarre Reality of Black Holes
- Every Symmetry is Associated with a Conservation Law
- GPS uses relativity for accuracy
- Time Dilation Goes Both Ways
- The Pole-Barn Paradox and Solution
- The Enormous Kuiper belt
- Time is a Fourth Dimension
- Electric Charge is not the only type of Fundamental Charge
To see the other Super Facts click here
Electric Charge is not the only type of Fundamental Charge
Super fact 59 : Most people have heard of electrical charges, positive and negative. However, in nature there are also color charges—red, green, and blue—which are analogous to electric charges. In addition, there are anti-red, anti-green, and anti-blue charges.
Esther’s writing prompt: 10th September : Charge
Click here or here to join in.
As you may know, atoms consist of particles. Electrons surround the nucleus of the atom. The nucleus of the atom is in the middle of the atom and it consists of protons and neutrons. Electrons have a negative charge. Protons have a positive charge. Neutrons do not have an electrical charge. Electrons are so called elementary particles. They are not composed of other particles. Protons and Neutrons, on the other hand, are not elementary particles. They are composite particles consisting of quarks, gluons and quark pairs called mesons.
Quarks have electric charges, just like an electron and a positron, which is why a proton has an electric charge, a positive electric charge. However, in addition quarks have something called color charge. Unlike electric charges, which come in two forms, negative and positive, they come in three forms red, green and blue and in anti-red, anti-green, and anti-blue (well six forms actually). I should say that the color charges, red, green and blue, are not real colors. They are just names. Just electric charges are associated with electric forces; color charges are associated with the nuclear strong force. The strong force is even stronger than the electrical force.
If you take an equal amount of positive and negative electric charges you get something that is electrically neutral. If you take an equal amount of red, green and blue you get what is called white, or neutral. If you take an equal amount of red and anti-red you also get white. Any other mix gives you a net color charge.
I can add that gluons are elementary particles that in many respects are like photons. Light consists of photons. It is because of the photons that we can see. In addition, the photons transport electrical charge. Photons are massless elementary particles with the intrinsic spin of one, and they belong to a group of elementary particles called Bosons. Gluons transport color charge, and they are massless and have an intrinsic spin of one and belong to the same group of elementary particles called Bosons. Unlike photons, they are stuck inside the nucleus and unlike photons they never get to see the light of day. The pun was intended.
Matter, light, and electrical charges are all part of our daily life. We can touch matter, see light, and we come across electrical charge when we touch something that is charged or when we see lightning. However, we do not come across quarks, gluons, and color charges in our daily life because they are hidden at the center of the atoms. Yet they are fundamental to the existence of matter, of us. We know color charges exist, the existence of color charges is an important fact, and yet it is not a well-known fact and often a big surprise to people. Therefore, I think it is a super fact.
The 118 Elements and the 3,500 Isotopes
There are 118 known elements. Why not 500, or just 4 or 5, like the ancient Greeks believed? Each element is defined by it having a certain number of protons and the same number of electrons if it is to be electrically neutral. The problem with having more than one proton in the nucleus is that protons all carry a positive charge and therefore want to push each other away. Same charges repel and different charges attract. What saves the nucleus from blowing apart are the neutrons and the associated strong nuclear force (protons & neutrons) which is guided by the color charges. The quantum model for electricity is called Quantum electrodynamics or QED. The quantum model for color charges is called Quantum chromodynamics or QCD.
As you add more protons it becomes increasingly more difficult for the nuclear forces (strong and weak) to hold the nucleus together. The positive charge of the protons is pushing too hard. That’s why there are only 118 Elements. Another thing to note is that the number of neutrons does not have to be the same as the number of protons. This means that for each element there are several kinds of so-called isotopes. For example, carbon has six protons and six electrons (if the atom is electrically neutral) but the carbon atom / element can have six neutrons, seven neutrons, or eight neutrons. You call them carbon-12, carbon-13, and carbon-14, where the number represents the number of protons plus the number of neutrons.
It is the electrons that determine the chemical properties of an element, and therefore isotopes with a different amount of neutrons are chemically identical. However, they are different with respect to properties that relate to he nucleus, such as radioactivity/stability, and of course weight. Also, when atoms combine into molecules their chemical properties change drastically, but again that is due to the rearrangement of the electrons. There are around 3,500 known isotopes, most of them radioactive.
What is a Quark?
To learn more about Protons, Neutrons, Quarks, Gluons, Color Charges, and Quantum Chromodynamics you can watch this 10 minute video below.
Other Physics Related Superfacts
- Some Things Cannot be Known
- Radon Represents our Largest Exposure to Ionizing Radiation
- We are Star Dust
- The Speed of Light In Vacuum Is a Universal Constant
- Two events may be simultaneous for some but not for others
- The Strange Worlds of Exoplanets
- The vastness of space and the beginning of infinity
- The Bizarre Reality of Black Holes
- Every Symmetry is Associated with a Conservation Law
- GPS uses relativity for accuracy
- Time Dilation Goes Both Ways
- The Pole-Barn Paradox and Solution
- The Enormous Kuiper belt
- Time is a Fourth Dimension
To see the other Super Facts click here
Time is a Fourth Dimension
Super fact 58 : In relativity, time is considered the fourth dimension, inseparable from the three spatial dimensions to form a four-dimensional continuum called spacetime. Adding time as a fourth dimension, not (x, y, z), but (x, y, z, t), results in spacetime measurements called spacetime intervals that all observers can agree on.
Before relativity the distance between two points was the same for all observers. The distance between points is calculated using the Pythagorean theorem: (d^{2}=x^{2}+y^{2}+z^{2}). You calculate the distance between two end points in a coordinate system using Pythagoras theorem because the points make right angled triangles along the x-axis, y-axis and z-axis. See the picture below.
Let say you add another coordinate system (x’, y’, z’). The new coordinate system could be translated and rotated compared to the first one. The values of (x, y, z) and (x’, y’, z’) would be different and yet the distance between point-1 and point-2 would be the same. Well as long as you don’t change units, like using meters in one coordinate system and feet in the other. The distance between the points would be a so-called invariant. Now imagine that you forgot to include one coordinate in Pythagoras theorem, for example, y and y’ or x and x’, then your calculation for the distance would be different for the two coordinate systems. We need all coordinates, or all dimensions. See the picture below.
In relativity the length of objects, as well as the time between events is relative and varies from observer to observer. In other words, distance and time varies from coordinate system to coordinate system. However, if you add time to the three space dimensions and calculate the distance between events using the Pythagorean theorem for intervals (between two events): or (s^{2}= x^{2}+y^{2}+z^{2} – t^{2}) or (where the ‘t’ represents time in appropriate units), then the difference between different observers vanish. The interval is the same for all observers. It is a so-called invariant. The formula for the spacetime interval comes in a few different forms. One for distance like intervals (space distance bigger than time) (s^{2}= x^{2}+y^{2}+z^{2} – t^{2}), and one for time like intervals (time is bigger than the space distance) (s^{2}= t^{2} – (x^{2}+y^{2}+z^{2})). There is also one that includes the imaginary number (s^{2}= x^{2}+y^{2}+z^{2} + (it)^{2}). See below.
The interval concept was developed, not by Einstein, but by Hermann Minkowski (a few years after special relativity) and is often referred to as Minkowski space. Time is like a space coordinate but the opposite signs in the equation make it different. Based on articles I found it appears that the opposite signs (minus vs. plus) means that you cannot move “backwards” in time as you can in a space dimension.
I admit that this is a very abstract super fact, but it basically means that if you add time as an extra coordinate to the three space coordinates x, y, z you get something, the spacetime interval, that everyone regardless of speed, orientation, etc., agrees on, despite relativistic length contraction and despite time dilation and non-simultaneity.
Time Expressed in Appropriate Units
I would also like to explain what I mean by (where the ‘t’ represents time in appropriate units), as I stated in the above. For physical formulas to work they need to be expressed in consistent units. For example, you can’t use kilometers for the coordinate x, and miles for coordinate y, not without adding a constant to adjust for it. For the formula (s^{2}=x^{2}+y^{2}+z^{2}-t^{2}) to work you need to express time in a unit that corresponds the time light travels in one meter if x, y and z are expressed in meters. If you express x, y, and z in meters and express time in seconds you must adjust the formula with the constant c = 299,792,458, the speed of light in meters per second, so you get (s^{2}=x^{2}+y^{2}+z^{2}-(ct)^{2}). See the picture below.
Time Like Space Intervals
The formula for time like intervals is typically used for the situation where the time component is larger than the space component, which also means that it is possible to physically travel between the two events forming the space interval. As you can guess, that is a pretty normal situation. Let’s say you are watching TV and having a pizza. Your sofa is your coordinate system. You turn on the TV and 100 seconds later you move 2 meters to get a slice of pizza. Let’s calculate the spacetime distance between those two events.
The space component is easy, that’s 2 meters. However, if we express time in the time it takes light (in vacuum) to travel one meter we get 100 times 299,792,458. If you express time in seconds, you adjust it using the constant c = 299,792,458, and again you multiply 100 with 299,792,458, which is 29,979,245,800. So, the distance in time is almost 15 billion times larger. You really did not move far in space, but you moved very far in time. Now ask yourself. Are you spending your time well?
The Minus in Front of the Time Coordinate
There is one obvious difference between time and the space coordinates. In a coordinate system you can walk forward, along let’s say, the x-axis and then walk back the same way. You can walk back and forth as many times as you want, no problem, but you cannot do that with time. Time may be a space-time coordinate, but it is different from the other three coordinates in that way, and that’s where the opposite signs in the formula for the space-time interval comes in. This is beyond the scope of this super fact blog post, but you can read more about this here and here.
Other Relativity Related Superfacts
- The Speed of Light In Vacuum Is a Universal Constant
- Two events may be simultaneous for some but not for others
- GPS uses relativity for accuracy
- Time Dilation Goes Both Ways
- The Pole-Barn Paradox and Solution
To see the other Super Facts click here
Small Microscopic Subatomic and Strings
Esther’s writing prompt: 6th August : Small
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Small Things
Fire ants are small. They average 1/8 inch to 1/4 inch in length, or 3 to 6 millimeters. Mites are very small arachnids that are less than 1 millimeters. They are so small that they are difficult to see with the naked eye unless they are on a white sheet. However, amoebas are typically even smaller than mites. Most amoebas range from 10 to 500 micrometers in diameter. 500 micrometers is the same as half a millimeter. You typically need a microscope to see an amoeba. I should say that there are some large amoebas that are 2 millimeters.
Microscopic Things
If you want to go even smaller, much smaller, we can enter the microscopic world. Bacteria are microscopic, single-celled organisms with sizes typically ranging from 0.5 to 5 micrometers in length and 0.2 to 1 micrometer in width. That means that bacteria are around 100 times smaller than amoebas. Well, if you consider length. If you consider the volume that is a million times smaller. Comparing an amoeba to a bacterium is like comparing a horse to a small cicada. You certainly need a microscope to see bacteria.
If you think bacteria are small, I can tell you that viruses are even smaller. Viruses typically range in size from 20 to 300 nanometers in diameter. 1000 nanometers is 1 micrometer. A small corona virus (SARS-CoV-2) is 50 nanometers, which is 20 times smaller (in diameter) than a bacterium that is 1 micrometer in size and 100 times smaller (in diameter) than a bacterium that is 5 micrometers. Again, a horse to a medium size insect.
Atoms Are Very Small
Atoms are much smaller than viruses. This reddit user calculated that there are roughly 52 million atoms in a normal sized covid virus (100 nanometers). Also keep in mind that there is a lot of space between atoms. The size of a hydrogen atom is 0.1 nanometer or 100 picometer. Comparing a hydrogen atom to a normal sized covid virus is like comparing a flea to a horse. If you consider volume, you could fill a normal sized covid virus with 1 billion hydrogen atoms.
You cannot see an atom using a regular microscope. You must use specialized microscopes that don’t rely on visible light to see atoms, such as scanning tunneling microscopes and electron microscopes. So, in summary, a hydrogen atom is to a normal sized covid virus like a flea is to a horse, and a normal sized covid virus is to a 100 micrometers amoeba (small sized amoeba) like a flea is to a horse.
Below is an illustration of a Helium atom, which is the next element after Hydrogen. A Hydrogen atom has one electron and one proton and possibly one or two neutrons. A stable Helium atom has two electrons and two protons and one or two neutrons.
Subatomic Things
But let’s go smaller, much smaller. A hydrogen atom is gigantic in comparison to subatomic particles. Most of the mass in an atom is concentrated in the nucleus, which consists of protons, neutrons, quarks and gluons, and quark pairs called mesons. The size of an atomic nucleus varies, but it typically ranges from 1.6 femtometers (1.6 x 10⁻¹⁵ meters) for a proton to about 15 femtometers for the heaviest atoms.
I should say this is difficult to estimate so take this with a grain of salt. In any case that makes the hydrogen atom about 100,000 times wider than the nucleus in its middle. If the hydrogen atom was 100-meter giant ball the nucleus in the middle would be just 1 millimeter (half the size of a flea). That is despite the fact that the vast majority (+99.95%) of the mass of the atom is in the nucleus. In this case, we are not comparing a flea to a horse, but a flea to a mountain. A mountain of mostly empty space with a super massive flea at its center. The YouTube video below explains the details.
Strings Are Extremely Small
However, the smallest things there are, might be strings. Strings, in the context of physics, are one-dimensional, extended objects that are thought to be the fundamental building blocks of the universe. These strings vibrate at different frequencies giving rise to elementary subatomic particles. Strings are thought to be about 10^-35 meters, which is 100,000,000,000,000,000,000 times smaller than the atomic nucleus described above. Comparing a string to a nucleus would be like comparing the hydrogen atom to a ball, or a giant star, containing one billion planet earths. I should mention that string theory has not been experimentally confirmed.
That is small, very small, extremely small, as small as it can get.
This post is not a super fact since it features a lot of facts and not all of them confirmed or exact.
Super Facts 