What causes a sonic boom?

Many do not make sense about the story about sonic booms or explosions. Columbia Encyclopedia 5th edition (1993) says, "An object like an airplane, for example, produce sounds. When the sound of it reaches or exceeds the speed of sound, the object is caught up with the noise itself. "

On the other hand, many people believe there is something called "sound barrier" or the sound barrier, also that when the plane flew past him he issued a loud bang, as if he had hit an invisible glass wall. It is also wrong.

Everyone must tergiring to such thinking by the use of the term "obstacle" or barrier. This term was never meant to imply physical obstacles in the sky there, but only that the speed of sound to present obstacles to the development of faster aircraft lebh.

The definition of sound barrier is a barrier in aeronautics design context, not a physical obstacle. However, when the plane "bypass" the sound barrier, it is clear there are a number of physical stress experienced by the aircraft due to the shock wave (shockwave).

Real obstacle to supersonic flight posed by the speed of sound itself. (And of course supersonic means faster than the speed of sound, while the ultrasonic refers to the sound with higher frequencies than humans can hear.) In fact a lot of unique things happen when the object approached the speed of sound in air.

The plane flew through the air with a speed of several hundred km / hour. The speed is low enough this allows air molecules to stay relaxed when it should be brushed to give way; the situation is more or less like when someone is walking slowly lifted the crowd.

But when the speed of the aircraft to be proportional to the speed of the molecules, the molecules could not escape, they piled on the edges of the front of the plane and driven with him.

Rapid buildup of pressurized air is produced "air shocks" or shock waves, which form the explosion. The sound waves radiate in all directions and can be heard sebaga an explosion by the people down there.

What does all mentioned with the speed of sound? Well, the sound is nothing but a series of air compression and expansion.

If the air molecules around a certain speed, then there is a limit to how fast air can be compressed and dimuaikan, because molecules can not be compressed and dimuaikan faster than the motion of each against the other. That is why the speed of air molecules put limits on how fast sound can travel it.

The sound will propagate faster in warm weather ketimabng in cool air and the sound is also progress faster in dense high-pressure air.

That's why supersonic aircraft operate best at very high altitude cold areas, because they do not need to be going too fast to exceed the speed of sound. At an altitude of 9 km above sea level, the air cool and thin enough so that the sound speed is only 1100 km / hour.

What causes a sonic boom?

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Like Physics Through Imagination

Imagination is more primary than knowledge. Knowledge is limited. Imagination encompasses the world. -Albert Einstein. Speaking of physics can cause a variety of responses. Not gossip again if physics is one of the "ghost" that dreaded by many students, both in the secondary level, general, and even in college.

Some people memorize physics formulas like a history book without realizing its meaning.
There is also a resigned because he considered physics belongs only to people who are serious, intelligent, crazy math, and in general "less slang."

In fact, not a few who think that making life physics as a career is the wrong choice because "the entry of" easy but "out" difficult. In other words, a student of physics is not difficult but lulusnya half dead and it works at most be a teacher or if lucky enough to be a lecturer.

Some admire physics students because reading the news about the success of the Olympic team of physics or reading a book about the lives of great scientists. Unfortunately, many also admired not only to appreciate or learn physics. Often people who master the physics are considered as the "cool" and "weird" for wanting to learn something difficult, but if so it could be wealthy businessman.

Such perceptions lead to the general public tend to be fond of other sciences such as metaphysics. While other countries try to sensitize the people for not "gatek" aka stammering science and technology of our country through some mass media seems to work hard to convince people not to "gagib" or stutter supernatural.

In fact, the submission of this information using the application of physics and electronics. In short, find someone who likes physics is like looking for a pin in a haystack.

Lots of students or students who are patiently awaiting delivery of physics formulas on the blackboard, then working on the problems of physics. From experience, the problems were solved by means of "mutual assistance" because only a few people are able or willing to do it. The success of teaching does not seldom based on the ability to do the final exam questions, rather than on mastery of the physical meaning of the formula.

For example, almost everyone in the class know Newton's second law, F = ma, but probably never imagined that such formulas can tell you why fat people would rather play tug of war than 100m.

Then, who is not familiar with Einstein's famous equation E = mc2? Unfortunately, very few people know that the mass of a book containing the basic physics of energy that can bring a spacecraft to the moon!

One cause of negative perceptions about physics is that science is often taught without appreciation so that was annoying. In fact, the physics we can know many things. A student who began studying the science does not need all the way to visit the laboratory to see the phenomena of physics.

Whenever and wherever he can imagine (menghayal) on the surrounding environment.
The beauty of the flower color is visible to the eye, comfortable-sounding music in the ears, enchanting waterfalls, the cool air flow, are few examples of the physics of everyday phenomena.

The explanation that every color has a wavelength that is different, and that objects absorb and radiate certain wavelengths, so get to our eyes, can be read in a physics book. But often people do not care about the explanation for not imagining that he forgot the beauty of nature and have no curiosity.

Imagination is born from an environment that supports a person for thinking about various phenomena around it. If the local community or family at home does not appreciate the freedom of thought, the power of imagination is difficult to develop. Almost all famous physicists are people who like imaginative thinker and is often described as "radical" because it was considered strange by the environment are often dogmatic.

Einstein is a popular example of people who like their imagination and develop it. He imagines what if he can move with the speed of light. Thinking this odd result in the theory of special relativity, which until now still used. The same is done by Newton. If only she did not like daydreaming under the apple tree may be the law of universal gravitation was not discovered until decades later.

Through imagination, consciousness to observe natural phenomena and reading physics books would present itself. For example, water molecules (H2O) consists of two hydrogen atoms and an oxygen atom. We certainly can not see the water molecules with the naked eye. However, we can imagine that the molecules are very small, so do not appear.

Accordingly, the number of molecules that make up a body to be very much. Through the imagination we are thrilled to learn that a mole of molecules of water (which weighs about 18 grams) contains about 6 x 1023 molecules. So, one tablespoon of water was composed of approximately 1022 molecules. The amount is very large. If the entire population of Indonesia was given the task to calculate the different molecules one by one every 5 seconds then it takes billions of years!

Physicists do not make the formulas to be memorized or written on the palm. Formulas are made to understand natural phenomena in a concise, beautiful, universal, and useful for solving problems related to such phenomena. Indeed, physics is not possible apart from mathematics.
Without the mathematical definition, physics is very difficult to develop and dimanfanfaatkan as technology.

However, to learn the basics of physics one does not need to be "crazy" mathematics or become serious and fear can not be a boyfriend because of "lack of slang." Learning physics is not easy, but with escape from dogmatic thinking and desire to think freely, imagination will appear and can be a fun adventure for anyone.

River Gorge in South Africa matchless beauty store. Lots of physical phenomena that make the scene above is breathtaking: Legal reflection and refraction produce a picture 'of the mountain upside down' is seen above the river surface. Polarization of sunlight by molecules in the air to give blue scenery is very harmonious with the colors green and brown.

Wind due to the difference in air pressure move the tree foliage in terirama. Looks an animal consumes food and drink to sustain life, a process of reducing the entropy (disorder) by adding energy in the animal. Physics Is not it beautiful? (Taken from the Microsoft Reference Library 2003. Encarta)

Like Physics Through Imagination

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Breakthrough obstacles, Through the Horizon

Hawking radiation is often intuitively visualized as particles that have been through (barrier) horizon. However, it is not clear where the barrier that must be breached. The key is to implement the conservation of energy, so the black hole contracts during the radiation process.

A direct consequence is a spectrum of radiation can not be entirely thermal. Amendments to the thermal spectrum is expected from the characteristic shape keuniteran quantum theory. This may just may be a clue to the puzzle of information black hole.

Classically, a black hole is an absolute jail, all that goes into it must be locked, there's no way out. Furthermore, because no one can come out, a classical black hole can only grow 'big' as time passes.

Then, at the time, was a shock to physicists as Hawking showed that quantum mechanics can actually be a black hole radiates particles. With the issuance of this Hawking radiation, black holes can lose energy, shrink, and then eventually evaporate completely.

How can this happen? When an object which is classically stable (fixed energy, no change) into a quantum mechanics becomes unstable (no change), then naturally we would expect that there is a breakthrough barrier (tunneling).

Clearly, when it was first proved the existence of Hawking radiation of black holes, he described it as a breakthrough barrier triggered by vacuum fluctuations (the appearance of particles and antiparticles of the combined system with initial energy = zero, vacuum) in the near horizon. Previously, the horizon is the bulkhead between the 'in' and 'outside' the black hole where light can not get out of him.

Therefore, we call these black holes are 'black' because there is no information (classically) that arrive at the observer.

Hawking's idea is right around the pair production event horizon, inside or outside. Particles with positive energy created by pair production in the horizon will break through the barrier horizon - though no klask trajectories are possible, but this can be allowed quantum. In this case we can imagine antiparticle (negative energy) that remains in the horizon of a black hole resulting in the total energy decreases.

Then, if the right pair production occurs outside the horizon, then antipartikelnya that comes into the horizon, and we can imagine the effect is the same as before. There are particles that 'run' away from the black hole (this is the radiation) and the resulting energy (mass) black hole is reduced.

But unfortunately, although the picture of Hawking as described above, but the original reduction was not initially take advantage of this picture is complete. It's quite odd.


 To take full advantage of this picture, we need to solve 2 problems: One is technical, to conduct breakthrough calculations barrier, it takes a well-behaved coordinate system on the horizon (no infinity). Second: Conceptually, what barriers must be breached?

Usually, when the barrier breakthrough occurs, there are two separate areas which combined classic by a trajectory in imaginary time / complex.

In the WKB limit (a term approximation in quantum), the opportunity to break through barrier associated with the imaginary part of the action (particle) when passing through a classically forbidden trajectory with the expression

    G μ exp (-2 Im S)

with S is the action on the related trajectory. But the problem arises when this technique is used for black holes. Apparently, the 'outside' and 'in' this horizon zero cm apart in distance. Tell a separate pair of particles produced by infinitesimal beyond the horizon, but he still can 'run'. How can this happen?

As Hawking initially described, that particles break through the horizon, this is indeed happening. But his explanation to the argument that a little complicated, because there is no barrier which had previously been there (been there By design).

However, what happens is that particles break through the barrier he created his own (remember the relativity, the motion of objects is determined by the surrounding geometry, this geometry is determined by the content of the mass and angular momentum of the black hole). The most important point that energy must be conserved. When the radiation occurs, the energy / mass black hole decreases, the more he shrank.

This shrinkage effect on the small radius of the black hole. The size of the contractions that occur naturally depend on the number of particles of energy that comes out. The bigger the energy out, the greater the contraction also occurs. Here it will be seen that the particles that come out that is what defines the barrier. But we will see this more clearly in the next section.

More details of course we really need a complete theory of quantum gravity here (which is still far from final). Tell the generally accepted point of view, we need to involve graviton (gauge fields that mediate interactions in quantum gravity, such as photons for quantum electromagnetic interaction).

But as we discuss the symmetry of black hole systems the ball, then no analysis is required graviton which has spin 2, because then the ball would not algi symmetry. All it takes is parikel spin zero (scalar) so that the degrees of freedom which will be discussed only when there was breakthrough parikel position barrier.

Armed with this view, we can do the calculations to break through the barrier in the Hawking radiation. Coordinates are used just as it certainly is not a standard like Schwarschild, because in these coordinates the horizon is not of good character, there is lack berhinggaan for spatial sector radius, dr.

But with the transformation of Painleve (which finds a transformation as a critique of general relativity in which the singularity can be removed only with a trasnformasi coordinates). Line element due to this transformation to the original geometry is Schwarschild

DS2 =- (1-2M / r) dt2 +2. sqrt (2M / r) + dr2 + r2dX2 dtdr

with the DX2 is the metric for 2-dimensional ball.

With this line element, we can calculate the safe integral of the particle action (p.dr with p = momentum and dr = infinitesimal radius). The integration radius is the horizon radius at first, until the particles have come out, with energy E, ie from r = 2M to r = 2 (ME).


Integral is analogous to the integral calculation of the probability of normal barrier breakthrough. It is clear that the barrier in the Hawking radiation depend on the particle energy out, as has been alluded to earlier.

By equating exp (-2 Im S), the calculation of the Boltzmann factor, exp (E / T) with T = temperature of Hawking, Hawking temperature, it can be found such that at first found first.

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Using of Uranium

Uranium is a mineral that emits nuclear radiation or radioactive, used in various fields, one of which is as nuclear fuel. Uranium is a chemical element in the periodic table that has the symbol U and atomic number 92.

A heavy metal, toxic, silvery white and naturally radioactive, uranium belongs to the actinide series (actinide series).

Uranium is usually present in small amounts in rocks, soil, water, plants, and animals (including humans).

Uranium has 3 isotopes:
- U234 very small levels
- U235 content of 0.715 = 0.7%
- U238 levels of 99.285 = 99.3%

U235 isotope is used as fuel for nuclear reactors and nuclear weapons.

Uranium has the typical physical properties:
- Found in nature in the form of UO U3O or yellowish-green and dark brown.- When exposed to ultraviolet light, the fluorescence of uranium will issue a very beautiful light

In nuclear physics, a nuclear reaction is a process in which two nuclei or nuclear particles collide, to produce different results from the initial product. In principle a reaction can involve more than two particles collide, but the incident is very rare.

When the particles collide and separate without change (except perhaps in the energy level), this process is called a collision and not a reaction.

Known two nuclear reactions, namely nuclear fusion reactions and nuclear fission. Nuclear fusion reaction is the fusion reaction of two or more atomic nuclei into new and produce energy, also known as a clean reaction.

Nuclear fission is the splitting reaction of atomic nuclei by the impact of other atomic nuclei, and generate new energy and atomic mass is smaller, as well as electromagnetic radiation.

Fusion reaction also produces alpha radiation, beta and gamma that are dangerous to humans.
Examples of nuclear fusion reaction is a reaction that occurs in almost all core stars in the universe.

Weapons of the hydrogen bomb is also utilizing the principle of uncontrolled fusion reaction. An example is the explosion of fission nuclear weapons and nuclear power plants.

Elements that are often used in nuclear fission is plutonium and uranium (primarily plutonium-239, Uranium-235), while in nuclear fusion reactions are Lithium and Hydrogen (mainly lithium-6, Deuterium, Tritium).

Using of Uranium

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Antimatter

Matter is anything that we know as the composer of this entire universe, and proved its existence. But in addition to the material as a natural constituent, there are also antimatter, that is something that the masses and properties similar to the same material, but different charge. Examples are the positron, which is the antimatter of an electron. That is a positively charged electron particles.

One time, scientists have found beams of light and particles that hit the Earth from all directions. They believe that the particles are not from the sun, stars, galaxies, or any other celestial body. They suspect these particles are the traces of the remaining big bang. After investigation, they find that the particle is a twin of the electron, but positively charged. They call it a positron.

In essence, the material is composed of fundamental elements or basic elements. And antimatter is composed of antiparticles of the particles of matter.
Fundamental elements are not atomic, because the atoms can still be divided again. Nor protons, electrons, or neutrons. Because all three composed again by two things so far considered the most fundamental, namely the so-called Quark and lepton.

Uniquely, antimatter can not interact directly with the material, because they will destroy each other, something called Annihilation. Even with air (or whatever hyperbole is more subtle than that). Einstein said that matter is energy trapped. And that energy can escape when the layers are opened concurrently. With the meeting of matter and antimatter (plus-minus, complement each other), open the wrapper layer, and irrespective of both the energy out of 100 percent. Know what it means? There is no combustion, no dust, no pollution. Is perfect for most lux fuel and futuristic. But the dark side is only one gram of antimatter could replace more powerful nuclear bomb to re-bomb Hiroshima as ever. This reaction is 1000 times greater than nuclear fission and 300 times more powerful than nuclear fusion.

Carl Anderson first discovered the existence of antiparticles in 1932, at Fermilab, Chicago, USA. Positive electrons can be detected in the cosmic radiation flux on the surface of the earth. Anderson uses foam room observers compiled by liquid hydrogen.

He fired charged particles into the chamber containing superheated liquid bubble surrounded by a magnetic field. If there is a charged particle through the liquid hydrogen, the hydrogen atoms are ionized so that the pass will lead to foam along the path. If the foam is exposed to light, we can observe the traces of charged particles generated earlier. Through some photos taken, Anderson observed that there is a mass charge equal to the electron but curved in the opposite direction. Positive electrons.

If the universe / universe composed of matter and antimatter, it is logically necessary space to separate the two so as not to eliminate each other. The empty space we call antiuniverse. Until one time universe and antiuniverse met and there was an explosion of gamma. When the explosion the Big Bang, matter and antimatter created in a state of balance. But the fact is material we discover much more about us than antimatter.

The hypothesis states that the formation of the universe is broken assymetry (symmetry is torn). At the time of the birth of the universe is estimated to 1032 degree Kelvin temperature and everything is contained in the form of radiation. At the next time there symmetry that produces mass destruction.
The material is formed after the big bang called spontaneous broken symmetry (simatri spontaneous destruction). When the big bang took place, the excess material at 10 ^ 8 or 10 ^ 9 x 99.999999 percent of the material along with all the antimatter annihilated, so that 0.000001 percent of the materials that make up the universe today. Another comparison of estimates versus 30 million 30.000.0001 quark antiquark.
However, there is assymmetry baryons, namely the asymmetry between baryons and fermions which reacted strongly against the antibaryon. The theory which explains the asymmetry of baryons is called baryogenesis, where the birth of the baryons are non-zero numbers. This occurs when there is no balance / out of equilibrium.

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