Today I want to continue explaining about Einstein Special relativity.
BUT! I forgot to say I'm not major in physic, so there may be mistake. Please tell me if you notice my mistake.
To know what is whatever you want, what will you do? It is effective to know or understand what will happen result from it. So I want to explain "light clock".
This is made from a light resource and a mirror these can move parallel with right angled direction of straight between the mirror and the resource. In addition you already know the distance between the mirror and the light resource and the light velocity---this is constant. Then light from the light resource, the mirror reflects light, light comes back. You can calculate a time that is used to go and back between two. You can use this time as clock.
"Hmm, clock? This is a kitchen timer, isn't it?"
Oh, it is likely and exactly. But do you know what property "clock" has to have? It is only Kitchen timer! If you want to know one second using this light clock, you should set a distance 299 792 458 m. The distance is distance light can reach in one second.
Anyway, we shall go to next step. The next experiment is to move equipments! Move equipments as velocity whatever you want to move these. Then imagine light from light resource, light go and come back..., but equipments are moving. Look at from outside of equipments, light goes more distance than the experiment we had just before.
Please DON'T be cheated by common sense!
Light velocity is constant, so light use more time to go the mirror. Why? Line light goes is oblique across the light resource and the mirror. If we've set the distance 299 792 458 m, more than one second is used to go one light velocity second. What is happen? Time lags!
You can't believe this fact, but many experiment shows time lag when you move or I move. "Move " is important factor. It is difficult to explain other experiments, but you will see those in wikipedia: Special_relativity and so on. If you are not good at math, you can read Einstein's paper about Special relativity. It is very good way to know and think about Special relativity to read it.
2012年1月20日金曜日
Einstein's Special relativity
I want to explain Einstein's theorem "Special relativity" using two blog article. Today and next week. First week, I want to explain about basic fact of the theorem, "principle of constancy of light velocity".
But, this experiment was failure. The interference fringe size was too small to prove existence of Aether. After this experiment, there were many experiment to prove existence of Aether. But there were no good result to prove.
There has been many experiment to measure light velocity. Galileo also had the experiment using two lamps. It is easy, two lamps are covered, one person(we call him "A") uncover the lamp, the other(we call him "B") uncovered lamps when "B" watch a lamp's light. Then "A" measure a round trip time of light. At last We use easy math, divide distance between "A" and "B" by the time makes light velocity. But this experiment was not succeeded. Light velocity is too high to measure on Earth.
There are some experiments of light velocity that can measure light velocity. But it is not sure what meditate light, like air meditate sound. Before 19th century, it is said "aether" meditate light, but no one prove existence of aether. Aether meditate light, but we can't see, touch, smell, and hear that.Then, if we want to prove existence, what we have to do?
Imagine a train, you are in front and I am in the rear. I say "Hello!" to you, then you hear that. sound velocity will be same if you say "Hello!" to me. Then, we moved to an open goods wagon, I say "Hello!"......what will be? Sound velocity is not same you say to me.because air that meditate sound is not moving with us. Sound velocity from me to you is more slow than one from you to me.
In 19th century, scientist thought that in light. If Earth and us are moving in space, we can measure of effect of aether. Light velocity from Earth to the direction of the movement of Earth is more slower than light from Earth to the right angled direction of the movement of Earth.
Michelson-Morley experiment
Albert Michelson and Edward Morley had this experiment. They wanted to know how Aether effect on light velocity. They made a skillfull laboratory equipment. Light from "coherent light source" is split to two light by semi-silvered mirrors, one goes in the direction of the movement of Earth and the other goes in the right angled direction of the movement of Earth, reflected two light go to detector. If Aether exists, there are differences between two light velocity, then interference fringe would appear. They wanted to measure this.
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But, this experiment was failure. The interference fringe size was too small to prove existence of Aether. After this experiment, there were many experiment to prove existence of Aether. But there were no good result to prove.
This experiment suggested one fact. It is "Hmm, if this experiment is true, Aether does'nt exist? And, light velocity is constant?"
Yes it is!
I want to show abstract of Einstein's special relativity in next week using this fact.
***************************************************************
Now, we have more and more accurate
result using laser equipment. Light velocity is
299 792 458 m/s in SI(The international System of Unit)
***************************************************************
Now, we have more and more accurate
result using laser equipment. Light velocity is
299 792 458 m/s in SI(The international System of Unit)
***************************************************************
Quoted from...
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ガードナーの相対性理論入門 マーティン・ガードナー著 金子 務訳 白揚社 2007/12/31
2012年1月19日木曜日
Pendulum Foucault, Sun and us.
What is this---the Pendulum Foucault?
It is just a pendulum, you know, but also important and sensational one......
You know, Earth spins. But, before Nicolaus Copernicus in 16th people think Sun go around Earth. It was very likely, and it is likely for us without study about physic. Today, I want to show easy experiment to prove Earth spins. It is the Pendulum Foucault.
On February 1851, in Pantheon de Paris, Foucault held experiment. He isn't professional scientist, but he is very skillfull to have scientific experiment. He had had a preliminary experiment in his house before the experiment in Pantheon de Paris.
Foucault's hypothesis is about Earth's spin and a pendulum. At that time, although Earth goes around Sun but there are no method to prove that by physical. His hypothesis uses "Coriolis power". What is this?
Coriolis power do NOT really exists, but we can see this. Coriolis power is made by missing the fact we are on the Earth. Please imagine a disc and a ball on the center of disc. And rotate a disc and roll a ball out of disc straightly and see from above these. OK, you saw the ball is go straightly. Then please see from the disc, you are also rotating. Or to imagine, you can use a merry-go-round, a ball is rolled from center of it and you run by speed is same a merry-go-round. What you see? It is "the ball makes a curve"! This is Coriolis power. There is no power, but we thinks there IS power. Because it is easy to think.
Go back to Foucault Pendulum. His hypothesis is "If Earth spins, Coriolis power will be observed, and it is expressed by a pendulum's orbit. Coriolis power makes it off to the side (except for the equator). " He set a big pendulum in Pantheon de Paris. Finally, the pendulum's orbit was off to the side. Earth is spinning!
See also......
http://www.calacademy.org/products/pendulum/
http://en.wikipedia.org/wiki/Foucault_pendulum
It is just a pendulum, you know, but also important and sensational one......
You know, Earth spins. But, before Nicolaus Copernicus in 16th people think Sun go around Earth. It was very likely, and it is likely for us without study about physic. Today, I want to show easy experiment to prove Earth spins. It is the Pendulum Foucault.
On February 1851, in Pantheon de Paris, Foucault held experiment. He isn't professional scientist, but he is very skillfull to have scientific experiment. He had had a preliminary experiment in his house before the experiment in Pantheon de Paris.
Foucault's hypothesis is about Earth's spin and a pendulum. At that time, although Earth goes around Sun but there are no method to prove that by physical. His hypothesis uses "Coriolis power". What is this?
Coriolis power do NOT really exists, but we can see this. Coriolis power is made by missing the fact we are on the Earth. Please imagine a disc and a ball on the center of disc. And rotate a disc and roll a ball out of disc straightly and see from above these. OK, you saw the ball is go straightly. Then please see from the disc, you are also rotating. Or to imagine, you can use a merry-go-round, a ball is rolled from center of it and you run by speed is same a merry-go-round. What you see? It is "the ball makes a curve"! This is Coriolis power. There is no power, but we thinks there IS power. Because it is easy to think.
Go back to Foucault Pendulum. His hypothesis is "If Earth spins, Coriolis power will be observed, and it is expressed by a pendulum's orbit. Coriolis power makes it off to the side (except for the equator). " He set a big pendulum in Pantheon de Paris. Finally, the pendulum's orbit was off to the side. Earth is spinning!
See also......
http://www.calacademy.org/products/pendulum/
http://en.wikipedia.org/wiki/Foucault_pendulum
2012年1月10日火曜日
On the origin of "stars" species---John Darwin
Do you know that stars also evolve? It does not means literary "strong star" eat "weak star", or something like that. It means a star's state from begin---born--- of star to end---death--- of star. State of stars is divided to three:"Birth of star", "Maturity of star" and "Stellar remnants".
Birth of star
Story starts with molecular cloud in the space. A molecular cloud mast have mass and be large: for example 1.2*10^37 kg and 9.5*10^14 km. A dense part of molecular cloud rotates and collapses, and as gas falling gas released gravitational energy as heat and it become like disc. A baby star becomes in the center of disk. The protostar is it. More gases in disk is falling down to protostar, and more the protostar become hotter.
If a protostar's masses less than 0.08 of solarmass, you can't see it in the sky. In this star, nuclear fusion(nuclear fusion of hydrogen and hydrogen) can't begin because it is too low temperature. Stars like this are known "brown dwarfs".Else, protostar can become star that shine in the sky. Anyway, the sun masses "1" solarmass. In the sun, nuclear fusion began about 13.7billion.
Maturity of star
The sequence of hydrogen and hydrogen nuclear fusion is called "main sequence star".
After this sequence, Stars like the sun becomes "Red giant". This stars become bigger and bigger. In these, nuclear fusion---but not hydrogen and hydrogen, they are hydrogen and helium--- is happening. If a star's mass less than 0.5 solarmass, this nuclear fusion doesn't happen. If all of hydrogen was cosumed, the star's core become smaller but a star expansion.
If star's mass is nice to happen nuclear fusion of more massive elements:carbon, neon and so on except for more massive than Ferrum---iron, these are made and these will be part of our world. If there were no such star, there are no planet human can and space is more simple.
Stellar remnants
If a star is more bigger, for example, a star that has over 40 solarmass, this star will be black hall,
or a star has 10~40 solarmass, this will make a neutron star. A neutron star is very massive---370 thousand ton per square meter (37t/m^2).
And a star has 0.8 - 3~4 solarmass will be white dwarf. What is white dwarf? It is dense star, solar mass is pressed in earth volume. A famous white dwarf is "Sirius B". Sirius is most bright star in the sky except for the sun. Sirius B is companion star of Sirius. You can't see this with naked eye. Main star of Sirius is too bright.
Birth of star
Story starts with molecular cloud in the space. A molecular cloud mast have mass and be large: for example 1.2*10^37 kg and 9.5*10^14 km. A dense part of molecular cloud rotates and collapses, and as gas falling gas released gravitational energy as heat and it become like disc. A baby star becomes in the center of disk. The protostar is it. More gases in disk is falling down to protostar, and more the protostar become hotter.
If a protostar's masses less than 0.08 of solarmass, you can't see it in the sky. In this star, nuclear fusion(nuclear fusion of hydrogen and hydrogen) can't begin because it is too low temperature. Stars like this are known "brown dwarfs".Else, protostar can become star that shine in the sky. Anyway, the sun masses "1" solarmass. In the sun, nuclear fusion began about 13.7billion.
Maturity of star
The sequence of hydrogen and hydrogen nuclear fusion is called "main sequence star".
After this sequence, Stars like the sun becomes "Red giant". This stars become bigger and bigger. In these, nuclear fusion---but not hydrogen and hydrogen, they are hydrogen and helium--- is happening. If a star's mass less than 0.5 solarmass, this nuclear fusion doesn't happen. If all of hydrogen was cosumed, the star's core become smaller but a star expansion.
If star's mass is nice to happen nuclear fusion of more massive elements:carbon, neon and so on except for more massive than Ferrum---iron, these are made and these will be part of our world. If there were no such star, there are no planet human can and space is more simple.
Stellar remnants
If a star is more bigger, for example, a star that has over 40 solarmass, this star will be black hall,
or a star has 10~40 solarmass, this will make a neutron star. A neutron star is very massive---370 thousand ton per square meter (37t/m^2).
And a star has 0.8 - 3~4 solarmass will be white dwarf. What is white dwarf? It is dense star, solar mass is pressed in earth volume. A famous white dwarf is "Sirius B". Sirius is most bright star in the sky except for the sun. Sirius B is companion star of Sirius. You can't see this with naked eye. Main star of Sirius is too bright.
2011年12月20日火曜日
How to search planets human can survive?
There are many many planets in the universe.
The Earth is one of them, and human can survive on the Earth. We have imagined and will imagine planets those we or lives can survive on it. It isn't able to search such planets because there are no method before. But now, we have method to search, it is physics!
We introduce the term "habitable zone". This means "A planet in this zone, water is possible to exist like liquid". Water is essential to lives. So it is important to know whether extrasolar planet can have it. If it can do, there is possible to lives survive on it.
Then, where is habitable zone? There are near a fixed star and center of galaxy. First called "circumstellar habitable zone(CHZ)" and, second called "galactic habitable zone(GHZ)". CHZ is near a fixed star. It is said CHZ is from 0.97AU to 1.39AU (AU = "astronomical unit" is average distance between the Sun and the Earth, almost 1.5*10^11 m). GHZ has no concrete definition, but it is said it is enough near center of galaxy to contain heavy elements to consturuct a planet like earth, and enough far from center of galaxy to avoid the blackhall of center of galaxy and radioactivity from supernova and other dangers.
Search a planet we or lives can survive!!
For example, the planet called "Gliese 581 d". This is planet of fixed star called "Gliese 581". This planet is in the CHZ, and discovered in 2007. At first, "Gliese 581 d" is not a planet lives can survive, because it is too far from "Gliese 581" and only one side of "Gliese 581 d" faces
to "Gliese 581". But later, Robin Wordsworth, Francois Forget and the others who are CNRS(Centre national de la recherche scientifique)'s scientists showed a possibility of surviving on this planet. The greenhouse effect keeps heat and red light from "Gliese 581" go through clouds of "Gliese 581 d" and warm the surface. It may have something alive on the surface.
How to see far away planets?
Hubble space telescope is one of methods. This was carried into orbit by a Space Shuttle in 1990 and named after the astronomer Edwin Hubble. Hubble space telescope's four main instrument observes near ultraviolet, visible, and near infrared. This is 600km far from the Earth' surface, it makes us to observe extrasolar world without a bad effect from the atmosphere and weathers.But, it is impossible to use observation about the Sun, because the Sun's light is too strong for the instrument. It can see very little stars, but when see the Sun it get blinded like a human.
There are another way to see extrasolar world. X-ray telescope is so. JAXA(Japan Aerospace eXploration Agency)'s X-ray astronomy satellite "Suzaku" can see in X-ray. X-ray astronomy is one of frontier of modern science. Techniques to carry budget into orbit makes easier to observe than on the ground. To see in X-ray makes us to discover dark stars or galaxies. Why can "Suzaku" do? "Dark " means in visible light! If you see in X-ray, you can understand the universe is bright.
Figure: This is a picture of Perseus constellation in X-ray over the picture of visible ray. In this picture, we can see a plasma that we can't see in visible ray. In X-ray, we notice there are high temperature plasma (10000000~100000000 C).
from: http://www.jaxa.jp/press/2009/11/20091102_suzaku_j.html
The Earth is one of them, and human can survive on the Earth. We have imagined and will imagine planets those we or lives can survive on it. It isn't able to search such planets because there are no method before. But now, we have method to search, it is physics!
We introduce the term "habitable zone". This means "A planet in this zone, water is possible to exist like liquid". Water is essential to lives. So it is important to know whether extrasolar planet can have it. If it can do, there is possible to lives survive on it.
Then, where is habitable zone? There are near a fixed star and center of galaxy. First called "circumstellar habitable zone(CHZ)" and, second called "galactic habitable zone(GHZ)". CHZ is near a fixed star. It is said CHZ is from 0.97AU to 1.39AU (AU = "astronomical unit" is average distance between the Sun and the Earth, almost 1.5*10^11 m). GHZ has no concrete definition, but it is said it is enough near center of galaxy to contain heavy elements to consturuct a planet like earth, and enough far from center of galaxy to avoid the blackhall of center of galaxy and radioactivity from supernova and other dangers.
Search a planet we or lives can survive!!
For example, the planet called "Gliese 581 d". This is planet of fixed star called "Gliese 581". This planet is in the CHZ, and discovered in 2007. At first, "Gliese 581 d" is not a planet lives can survive, because it is too far from "Gliese 581" and only one side of "Gliese 581 d" faces
to "Gliese 581". But later, Robin Wordsworth, Francois Forget and the others who are CNRS(Centre national de la recherche scientifique)'s scientists showed a possibility of surviving on this planet. The greenhouse effect keeps heat and red light from "Gliese 581" go through clouds of "Gliese 581 d" and warm the surface. It may have something alive on the surface.
How to see far away planets?
Hubble space telescope is one of methods. This was carried into orbit by a Space Shuttle in 1990 and named after the astronomer Edwin Hubble. Hubble space telescope's four main instrument observes near ultraviolet, visible, and near infrared. This is 600km far from the Earth' surface, it makes us to observe extrasolar world without a bad effect from the atmosphere and weathers.But, it is impossible to use observation about the Sun, because the Sun's light is too strong for the instrument. It can see very little stars, but when see the Sun it get blinded like a human.
There are another way to see extrasolar world. X-ray telescope is so. JAXA(Japan Aerospace eXploration Agency)'s X-ray astronomy satellite "Suzaku" can see in X-ray. X-ray astronomy is one of frontier of modern science. Techniques to carry budget into orbit makes easier to observe than on the ground. To see in X-ray makes us to discover dark stars or galaxies. Why can "Suzaku" do? "Dark " means in visible light! If you see in X-ray, you can understand the universe is bright.
from: http://www.jaxa.jp/press/2009/11/20091102_suzaku_j.html
2011年12月16日金曜日
What is the Physics?
http://www.ldoceonline.comphys‧ics [uncountable]the science concerned with the study of physical objects and substances, and of natural forces such as light, heat, and movement
This is "Express Tour for Modern Science".
I show genres of physics and one authority in it.
Mechanics & Lagrange
There are many mechanics, do you know?
Mechanics is most popular physics. And it is most likely to mechanics is first physics.
I could say mechanics is mother of physics.
Lagrange mechanics, Newton mechanics... Lagrange is one of persons who made mechanics. His full name is "Joseph-Louis Lagrange", 1736-1813.
Newton mechanics is not ultimate in classical mechanics. There are principles those Newton mechanics and others based on. Newton mechanics and Lagrange Mechanics is parallel. These two says same thing!! Why, they based on same principle.
Maybe we can discover two ultimate theories about universe......
Thermodynamics & Maxwell
Can we make perpetual motion?
"James Clerk Maxwell"(1831-1879) made a ideal daemon.
It is "Maxwell Daemon".
Before talk about Daemon, I explain this principle, the first low of thermodynamics.
The first law of thermodynamics means, "In all cases in which work is produced by the agency of heat, a quantity of heat is consumed which is proportional to the work done; and conversely, by the expenditure of an equal quantity of work an equal quantity of heat is produced." (Clausius)
There are two boxes A and B. In A, there are warm molecule (=have more momentum), In b, there are cold molecule (=have lesser momentum). A and B is connected, and there is a door between A and B that "Maxwell Daemon" can open and close. Then , "Maxwell Daemon" can decide which molecule can go to the other box. So if Daemon decide only warm molecule can go other side, the other box will hotter and hotter without energy! This means there are perpetual motion.
It is the paradox! Which is true?
"Maxwell Daemon" can't exit?
Or, principle is not true?
Electronics & Maxwell
Maxwell again! He is great physician.
He made "Maxwell equation", it describe about electromagnetic field. This indicate the principle of constancy of speed of the light.Newton dynamics caused paradox in 19th. In Newton dynamics show speed of light is not constant.Then, Einstein's "Special relativity" shows speed of light is constant.
Newton dynamics must be modified!
There are more physics genre, but it is hard to describe those, because it is too difficult!
Physics is close to math, and if you want to learn physics, you have to learn math now.
It is very difficult to say when physics started. Because I don't know what physics is!
In early age, there are no line between any studies.
Sophist is also physician, and physician is also sophist. (e.g. Demokritos)
It is theological, philosophical, and scientific term usually translated into English as "nature".
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