Showing posts tagged science
sayitwithscience: Charge, Parity and Time Reversal (CPT) Symmetry From our everyday experience, it is easy to conclude that nature obeys the laws of physics with absolute consistency. However, several experiments have revealed certain cases where these laws are not the same for all particles and their antiparticles. The concept of a symmetry, in physics, means that the laws will be the same for certain types of matter. Essentially, there are three different kinds of known symmetries that exist in the universe: charge (C), parity (P), and time reversal (T). The violations of these symmetries can cause nature to behave differently. If C symmetry is violated, then the laws of physics are not the same for particles and their antiparticles. P symmetry violation implies that the laws of physics are different for particles and their mirror images (meaning the ones that spin in the opposite direction). The violation of symmetry T indicates that if you go back in time, the laws governing the particles change. There were two American physicists by the names of Tsunng-Dao Lee and Chen Ning Yang suggested that the weak interaction violates P symmetry. This was proven by an experiment which was conducted with radioactive atoms of colbalt-60 that were lined up and introduced a magnetic field to insure that they are spinning in the same direction. In addition, it was also found that the weak force also does not obey symmetry C. Oddly enough, the weak force did appear to obey the combined CP symmetry. Therefore the laws of physics would be the same for a particle and it’s antiparticle with opposite spin. Surprise, surprise! There was a slight error in the previous experiment that was just mentioned. A few years later, it was discovered that the weak force actually violates CP symmetry. Another experiment was conducted by two physicists named Cronin and Fitch. They studied the decay of neutral kaons, which are mesons that are composed of either one down quark (or antiquark) and a strange antiquark (or quark). These particles have two decay modes where one will decay much faster than the other, even though they all have identical masses. The particles with the longer lifetimes will decay into three pions (denoted with the symbol π0), however the kaon ‘species’ with the shorter lifetimes will only decay into two pions. They had a 57 foot beamline, where they only expected to see the particles with slower decay rate at the end of the beam tube. In astonishment, one out of every 500 decays where from the kaons species that had a shorter lifetime. The main conflict with seeing the short-lived mesons at the end of the beam tube is because they are traveling relavistic speeds and therefore ignoring the time dilatationthat they are supposed to undergo. Thus, the experiment has shown that the weak force causes a small CP violation that can be seen in kaon decay.

sayitwithscience:

Charge, Parity and Time Reversal (CPT) Symmetry

From our everyday experience, it is easy to conclude that nature obeys the laws of physics with absolute consistency. However, several experiments have revealed certain cases where these laws are not the same for all particles and their antiparticles. The concept of a symmetry, in physics, means that the laws will be the same for certain types of matter. Essentially, there are three different kinds of known symmetries that exist in the universe: charge (C), parity (P), and time reversal (T). The violations of these symmetries can cause nature to behave differently. If C symmetry is violated, then the laws of physics are not the same for particles and their antiparticles. P symmetry violation implies that the laws of physics are different for particles and their mirror images (meaning the ones that spin in the opposite direction). The violation of symmetry T indicates that if you go back in time, the laws governing the particles change.

There were two American physicists by the names of Tsunng-Dao Lee and Chen Ning Yang suggested that the weak interaction violates P symmetry. This was proven by an experiment which was conducted with radioactive atoms of colbalt-60 that were lined up and introduced a magnetic field to insure that they are spinning in the same direction. In addition, it was also found that the weak force also does not obey symmetry C. Oddly enough, the weak force did appear to obey the combined CP symmetry. Therefore the laws of physics would be the same for a particle and it’s antiparticle with opposite spin.

Surprise, surprise! There was a slight error in the previous experiment that was just mentioned. A few years later, it was discovered that the weak force actually violates CP symmetry. Another experiment was conducted by two physicists named Cronin and Fitch. They studied the decay of neutral kaons, which are mesons that are composed of either one down quark (or antiquark) and a strange antiquark (or quark). These particles have two decay modes where one will decay much faster than the other, even though they all have identical masses. The particles with the longer lifetimes will decay into three pions (denoted with the symbol π0), however the kaon ‘species’ with the shorter lifetimes will only decay into two pions. They had a 57 foot beamline, where they only expected to see the particles with slower decay rate at the end of the beam tube. In astonishment, one out of every 500 decays where from the kaons species that had a shorter lifetime. The main conflict with seeing the short-lived mesons at the end of the beam tube is because they are traveling relavistic speeds and therefore ignoring the time dilatationthat they are supposed to undergo. Thus, the experiment has shown that the weak force causes a small CP violation that can be seen in kaon decay.

(Reblogged from hadron94)

Okay, does anyone know what dimensional analysis is?

mangacraz00:

We’re supposed to know it for physics… and I really really don’t get it….

You use dimensional analysis to check if your answer is in the right units. For example, if a question asks you to solve for the energy, but your answer is in kilograms, you made a mistake somewhere. 

To do this you break up all the types of units into mass, time, length, electric charge and temperature. For example, velocity becomes (length) / (time), force becomes [(length*mass) / (time)^2], etc. These can be combined/canceled to its most simple form, which should be the units of your answer.

Hope that helps. You can read more here

(Reblogged from mangacraz00)

Bell’s Theorem and Quantum Entanglement

Bell’s Theorem, introduced in 1964 by John Steward Bell in his paper On the Einstein Podolsky Rosen paradox, deals with the “spooky action at a distance” that is at the heart of so much quantum weirdness. The gist of the theorem is this: if there are local explanations for the results we see due to entanglement then there are a set of inequalities which the outcomes of the measurements must obey.

Lets go through a simple thought experiment. We have a particle source, that emits two entangled particles in opposite directions. We perform one of two measurements on each of the particles. The result of each of these measurements is +1 or -1. 

We can set each of the two detectors to either a or a’, b or b’. Thus we have 4 possible setups: ab, ab’, a’b and a’b’. To form the Bell inequalities, we take the +1 and -1 outcomes, multiply them together and add three of them and subtract one of them, like so:

ab +ab’ +a’b’ -a’b

We can think of these +1 and -1 values as local hidden variables. According to Bell’s theorem, no matter what the outcomes of each measurement is (+1 or -1), the equation above should never be greater than +2 or -2. But the weird thing is, in the actual experiments done in labs, we see this equation return values of +/- sqrt(2)*2. 

Well ok cool thanks Cyrus but what does that mean?

Well. This means that either quantum mechanics does not have local hidden variables, or our reality does not obey counterfactual definiteness. No local hidden variables means that our reality does not adhere to the laws of locality; that is, things that are very far spatially separated have the possibility of interacting in some way. If our reality does not obey counterfactual definiteness, we loose the ability to say that an object has a certain value before we measure it; our world has no meaning until we look at it.

Bottom line: quantum mechanics is super fucking weird.

Image credit goes to my philosophy professor. Read more here.

Ever wonder what a fingerprint looks like under a microscope?

I took these pictures under 5, 10, 40 and 100 times magnification of a Silicon Dioxide wafer with a tiny fingerprint on it. You can clearly see the rainbow colors of the oil on your skin (similar to when you see a rainbow in spilled oil). Moral of the story: your hands are really dirty. 

Just look how much fun you can have with a microscope with a camera attached to it!

mothernaturenetwork: Scientist creates lifelike cells out of metalResearcher says he has created living cells made of metal instead of carbon — and they may be evolving. o shi- View high resolution

mothernaturenetwork:

Scientist creates lifelike cells out of metal
Researcher says he has created living cells made of metal instead of carbon — and they may be evolving.

o shi-

(Reblogged from mothernaturenetwork)
The Ultimate Fate of the Universe There are many proposed ends to the universe. The key factor in determining which fate we will actually experience is the density of the universe: basically, it’s a battle between how much stuff there is and how fast the universe is expanding. If the universe expands indefinitely, it may experience a Big Freeze or Heat Death: The Big Freeze is a scenario under which continued expansion results in a universe that asymptotically approaches absolute zero temperature. It could, in the absence of dark energy, occur only under a flat or hyperbolic geometry. With a positive cosmological constant, it could also occur in a closed universe. This scenario is currently the most commonly accepted theory within the scientific community. A related scenario is heat death, which states that the universe goes to a state of maximum entropy in which everything is evenly distributed, and there are no gradients — which are needed to sustain information processing, one form of which is life.  Alternatively, if the universe’s expansion accelerates, our universe may be ripped to shreds in a Big Rip: In the special case of phantom dark energy, which has even more negative pressure than a simple cosmological constant, the density of dark energy increases with time, causing the rate of acceleration to increase, leading to a steady increase in the Hubble constant. As a result, all material objects in the universe, starting with galaxies and eventually (in a finite time) all forms, no matter how small, will disintegrate into unbound elementary particles and radiation, ripped apart by the phantom energy force and shooting apart from each other. The end state of the universe is a singularity, as the dark energy density and expansion rate becomes infinite. If the power of attraction overwhelms the expansion of space, the universe may stop expanding and start contracting into a Big Crunch: The Big Crunch theory is a symmetric view of the ultimate fate of the Universe. Just as the Big Bang started a cosmological expansion, this theory assumes that the average density of the universe is enough to stop its expansion and begin contracting. The end result is unknown; a simple estimation would have all the matter and space-time in the universe collapse into a dimensionless singularity. Or perhaps the universe will rebound, and a Big Bounce will follow a Big Crunch: According to one version of the Big Bang theory of cosmology, in the beginning the universe had infinite density. Such a description seems to be at odds with everything else in physics, and especially quantum mechanics and its uncertainty principle.[citation needed] It is not surprising, therefore, that quantum mechanics has given rise to an alternative version of the Big Bang theory. Also, if the universe is closed, this theory would predict that once this universe collapses it will spawn another universe in an event similar to the Big Bang after a universal singularity is reached or a repulsive quantum force causes re-expansion. Or hey, who knows. It may be true that the universe is in a steady state and it will never end. But don’t bet on it. So go out and have fun because before you know it you might be swimming in a sea of unbound quarks.  Quotes from Wikipedia. Image courtesy of wikipedia commons. Read more Here. View high resolution

The Ultimate Fate of the Universe

There are many proposed ends to the universe. The key factor in determining which fate we will actually experience is the density of the universe: basically, it’s a battle between how much stuff there is and how fast the universe is expanding.

If the universe expands indefinitely, it may experience a Big Freeze or Heat Death:

The Big Freeze is a scenario under which continued expansion results in a universe that asymptotically approaches absolute zero temperature. It could, in the absence of dark energy, occur only under a flat or hyperbolic geometry. With a positive cosmological constant, it could also occur in a closed universe. This scenario is currently the most commonly accepted theory within the scientific community. A related scenario is heat death, which states that the universe goes to a state of maximum entropy in which everything is evenly distributed, and there are no gradients — which are needed to sustain information processing, one form of which is life. 

Alternatively, if the universe’s expansion accelerates, our universe may be ripped to shreds in a Big Rip:

In the special case of phantom dark energy, which has even more negative pressure than a simple cosmological constant, the density of dark energy increases with time, causing the rate of acceleration to increase, leading to a steady increase in the Hubble constant. As a result, all material objects in the universe, starting with galaxies and eventually (in a finite time) all forms, no matter how small, will disintegrate into unbound elementary particles and radiation, ripped apart by the phantom energy force and shooting apart from each other. The end state of the universe is a singularity, as the dark energy density and expansion rate becomes infinite.

If the power of attraction overwhelms the expansion of space, the universe may stop expanding and start contracting into a Big Crunch:

The Big Crunch theory is a symmetric view of the ultimate fate of the Universe. Just as the Big Bang started a cosmological expansion, this theory assumes that the average density of the universe is enough to stop its expansion and begin contracting. The end result is unknown; a simple estimation would have all the matter and space-time in the universe collapse into a dimensionless singularity.

Or perhaps the universe will rebound, and a Big Bounce will follow a Big Crunch:

According to one version of the Big Bang theory of cosmology, in the beginning the universe had infinite density. Such a description seems to be at odds with everything else in physics, and especially quantum mechanics and its uncertainty principle.[citation needed] It is not surprising, therefore, that quantum mechanics has given rise to an alternative version of the Big Bang theory. Also, if the universe is closed, this theory would predict that once this universe collapses it will spawn another universe in an event similar to the Big Bang after a universal singularity is reached or a repulsive quantum force causes re-expansion.

Or hey, who knows. It may be true that the universe is in a steady state and it will never end. But don’t bet on it. So go out and have fun because before you know it you might be swimming in a sea of unbound quarks. 

Quotes from Wikipedia. Image courtesy of wikipedia commons. Read more Here.

Endysymbiotic Theory

I think this is one of the more beautiful theories in (non-physics) science. Basically: things in cells used to be other independent living things.

From Wikipedia:

The endosymbiotic theory concerns the mitochondria, plastids (e.g. chloroplasts), and possibly other organelles of eukaryotic cells. According to this theory, certain organelles originated as free-living bacteria that were taken inside another cell as endosymbionts. Mitochondria developed from proteobacteria (in particular,Rickettsiales, the SAR11 clade,[1][2] or close relatives) and chloroplasts from cyanobacteria.

The extreme of this theory is a theory known as Symbiogenesis:

Symbiogenesis is the merging of two separate organisms to form a single new organism. The idea originated with Konstantin Mereschkowsky in his 1926 book Symbiogenesis and the Origin of Species, which proposed that chloroplasts originate from cyanobacteria captured by a protozoan…

A fundamental principle of modern evolutionary theory is that mutations arise one at a time and either spread through the population or not, depending on whether they offer an individual fitness advantage. Nevertheless, this general case may not apply to all examples of evolutionary change. Indeed, genome mapping techniques have revealed that family trees of the major taxa appear to be extensively cross-linked—possibly due to lateral gene transfer.

fucking lol source View high resolution

fucking lol

source

Quorum sensing

From Wikipedia:

Quorum sensing is a system of stimulus and response correlated to population density. Many species of bacteria use quorum sensing to coordinate gene expression according to the density of their local population. In similar fashion, some social insects use quorum sensing to determine where to nest. In addition to its function in biological systems, quorum sensing has several useful applications for computing and robotics.

…

Some of the best-known examples of quorum sensing come from studies of bacteria. Bacteria use quorum sensing to coordinate certain behaviors based on the local density of the bacterial population. Quorum sensing can occur within a single bacterial species as well as between diverse species, and can regulate a host of different processes, in essence, serving as a simple communication network. 

Lego Large Hadron Collider will discover the building blocks of the Lego universe

iheartchaos:

Using 9,500 LEGO bricks over a 33 hour period, Sascha Mehlhase created this 1:50 scale model of the ATLAS experiment at the CERN Large Hadron Collider. The project cost roughly $2614 and measures 1m x 0.5m x 0.5m in size. Whether it will find the elusive L-shaped Lego piece you fucking swore you just saw in the bucket is still up in the air.

Read More

(Reblogged from iheartchaos)