Introduction to Special Relativity

Albert Einstein.

Introduction:

Special relativity (SR, also known as the special theory of relativity or STR) is the physical theory of measurement in an inertial frame of reference proposed in 1905 by Albert Einstein in the paper "On the Electrodynamics of Moving Bodies".

It extends Galileo's principle of relativity—that all uniform motion is relative, and that there is no absolute and well-defined state of rest (no privileged reference frames)—to account for the constant speed of light—which was previously observed in the Michelson-Morley experiment—and postulates that it holds for all the laws of physics, including both the laws of mechanics and of electrodynamics, whatever they may be.

This theory has a wide range of consequences which have been experimentally verified, including counter-intuitive ones such as length contraction, time dilation and relativity of simultaneity. It has replaced the classical notion of invariant time interval for two events with the notion of invariant space-time interval. Combined with other laws of physics, the two postulates of special relativity predict the equivalence of mass and energy, as expressed in the mass–energy equivalence formula E = mc², where c is the speed of light in vacuum.

The predictions of special relativity agree well with Newtonian mechanics in their common realm of applicability, specifically in experiments in which all velocities are small compared with the speed of light. Special relativity reveals that c is not just the velocity of a certain phenomenon—namely the propagation of electromagnetic radiation (light)—but rather a fundamental feature of the way space and time are unified as spacetime. One of the consequences of the theory is that it is impossible for any particle that has rest mass to be accelerated to the speed of light.

The theory was originally termed "special" because it applied the principle of relativity only to the special case of inertial reference frames, i.e. frames of reference in uniform relative motion with respect to each other. Einstein developed general relativity to apply the principle in the more general case, that is, to any frame so as to handle general coordinate transformations, and that theory includes the effects of gravity.

The term is currently used more generally to refer to any case in which gravitation is not significant. General relativity is the generalization of special relativity to include gravitation. In general relativity, gravity is described using noneuclidean geometry, so that gravitational effects are represented by curvature of spacetime; special relativity is restricted to flat spacetime. 

Just as the curvature of the earth's surface is not noticeable in everyday life, the curvature of spacetime can be neglected on small scales, so that locally, special relativity is a valid approximation to general relativity. The presence of gravity becomes undetectable in a sufficiently small, free-falling laboratory.

By: Prof. Bruce Knuteson:

Assistant Professor of Physics di: 
a. Massachusetts Institute of Technology
b. Enrico Fermi Postdoctoral Fellow di University of Chicago

Pendidikan:
a. University of California, Berkeley
b. Rice University

MIT Course Number: 8.20

Level: Undergraduate

1. Syllabus

2. Calendar 3. Readings 4. Assignments

5. Exams

6. Related Resources

7. Download Course8. Materials

Assignments (no solutions)

Exams and solutions

 

 

Course Highlights

This course is offered during the Independent Activities Period (IAP), which is a special 
4-week term at MIT that runs from the first week of January until the end of the month.

Course Description

This course introduces the basic ideas and equations of Einstein's Special Theory of Relativity. If you have hoped to understand the physics of Lorentz contraction, time dilation, the "twin paradox", and E=mc², you're in the right place.

Acknowledgements

Prof. Knuteson wishes to acknowledge that this course was originally designed and taught by: Prof. Robert Jaffe.

Kunjungi laman Prof. Knuteson:

http://www.bruceknuteson.com/

Himpunan Mahasiswa Pendidikan Fisika Indonesia

Himpunan Mahasiswa Pendidikan Fisika Indonesia

(Indonesian Physics Student Association)

Visi

International Quality in Physics Education

Misi

Is to enhance the understanding and appreciation of physics through teaching

Program

HMPFI bertujuan :

1. Mewujudkan cita-cita Proklamasi Negara Kesatuan Republik Indonesia, dan mempertahankan, mengamankan, serta mengamalkan pancasila dan Undang-undang Dasar 1945
2. Berperan aktif mencapai tujuan nasional dalam mencerdaskan bangsa dan membentuk manusia Indonesia seutuhnya
3. Berperan serta mengembangkan system dan pelaksanaan pendidikan nasional
4. Mempertinggi kesadaran dan sikap Mahasiswa Pendidikan Fisika, meningkatkan mutu dan kemampuan profesi guru di masa depan dan tenaga kependidikan lainnya
5. Menjaga, memelihara, membela, serta meningkatkan harkat dan martabat Mahasiswa Fisika melalui peningkatan kesejahteraan anggota serta kesetiakawanan organisasi.

Fokus:

Inovasi, Riset dan Pengembangan Pendidikan Fisika 

PENDIDIKAN DI INDONESIA : MASALAH DAN SOLUSINYA

OLEH : M. SHIDDIQ AL-JAWI

Pendidikan yang sekuler materialis-tik ini memang bisa melahirkan orang pandai yang menguasai sains-teknologi melalui pendidikan umum yang diikuti-nya. Akan tetapi, pendidikan semacam itu terbukti gagal membentuk kepribadian peserta didik dan penguasaan tsaqafah Islam. 

Berapa banyak lulusan pendidikan umum yang tetap saja "buta agama" dan rapuh kepribadiannya? Sebaliknya, mereka yang belajar di lingkungan pendidikan agama memang menguasai tsaqafah Islam dan secara relatif sisi kepribadiannya ter-garap baik. Akan tetapi, di sisi lain, ia buta terhadap perkembangan sains dan teknologi. 

Akhirnya, sektor-sektor modern (industri manufaktur, perdagangan, dan jasa) diisi oleh orang-orang yang relatif awam terhadap agama karena orang-orang yang mengerti agama terkumpul di dunianya sendiri (madrasah, dosen/guru agama, Depag), tidak mampu terjun di sektor modern. 

Jadi, pendidikan sekuler memang bisa membikin orang pandai, tapi masalah integritas kepribadian atau perilaku, tidak ada jaminan sama sekali. Sistem pendidikan sekuler itu akan melahirkan insan pandai tapi buta atau lemah pemahaman agamanya. 

Lebih buruk lagi, yang dihasilkan adalah orang pandai tapi korup. Profesional tapi bejat moral. Ini adalah Output umum dari sistem pendidikan sekuler. 

Mari kita lihat contoh negara Amerika atau negara Barat lainnya. Ekonomi mereka memang maju, kehidupan publik-nya nyaman, sistem sosialnya nampak rapi. Kesadaran masyarakat terhadap peraturan publik tinggi. Tapi, perlu ingat bahwa agama ditinggalkan, gereja-gereja kosong. Agama dilindungi secara hukum tapi agama tidak boleh bersifat publik. 

Hari raya Idul Adha tidak boleh dirayakan di lapangan, azan tidak boleh pakai mikrofon. Pelajaran agama tidak saja absen di sekolah, tapi murid-murid khususnya Muslim tidak mudah melaksanakan sholat 5 waktu di sekolah. Kegiatan seks di kalangan anak sekolah bebas, asal tidak melanggar moral publik. 

Narkoba juga bebas asal untuk diri sendiri. Jadi dalam kehidupan publik kita tidak boleh melihat wajah agama. Sistem pendidikan yang material-sekularis-tik tersebut sebenarnya hanyalah merupakan bagian belaka dari sistem kehidupan bermasyarakat dan bernegara yang juga sekuler.  Dalam sistem sekuler  aturan-aturan, pandangan, dan nilai-nilai Islam memang tidak pernah secara sengaja digunakan untuk menata berbagai bidang, termasuk bidang pendidikan. Karena itu, di tengah-tengah sistem sekularis-tik ini lahirlah berbagai bentuk tatanan yang jauh dari nilai-nilai agama.

Himpunan Mahasiswa Pendidikan Fisika Indonesia

Himpunan Mahasiswa Pendidikan Fisika Indonesia

(Indonesian Physics Student Association)

Visi

International Quality in Physics Education

Misi

Is to enhance the understanding and appreciation of physics through teaching

Program

HMPFI bertujuan :

1. Mewujudkan cita-cita Proklamasi Negara Kesatuan Republik Indonesia, dan mempertahankan, mengamankan, serta mengamalkan pancasila dan Undang-undang Dasar 1945
2. Berperan aktif mencapai tujuan nasional dalam mencerdaskan bangsa dan membentuk manusia Indonesia seutuhnya
3. Berperan serta mengembangkan system dan pelaksanaan pendidikan nasional
4. Mempertinggi kesadaran dan sikap Mahasiswa Pendidikan Fisika, meningkatkan mutu dan kemampuan profesi guru di masa depan dan tenaga kependidikan lainnya
5. Menjaga, memelihara, membela, serta meningkatkan harkat dan martabat Mahasiswa Fisika melalui peningkatan kesejahteraan anggota serta kesetiakawanan organisasi.

Fokus:

Inovasi, Riset dan Pengembangan Pendidikan Fisika

PENDIDIKAN DI INDONESIA : MASALAH DAN SOLUSINYA
OLEH : M. SHIDDIQ AL-JAWI

1. Pengantar 

Kualitas pendidikan di Indonesia sangat memprihatinkan. Ini dibuktikan antara lain dengan data UNESCO (2000) tentang peringkat Indeks Pengembangan Manusia (Human Development Index), yaitu komposisi dari peringkat pencapaian pendidikan, kesehatan, dan penghasilan per kepala yang menunjukkan, bahwa indeks pengembangan manusia Indonesia makin menurun. 

Di antara 174 negara di dunia, Indonesia menempati urutan ke-102 (1996), ke-99 (1997), ke-105 (1998), dan ke-109 (1999). Menurut survei Political and Economic Risk Consultant (PERC), kualitas pendidikan di Indonesia berada pada urutan ke-12 dari 12 negara di Asia. Posisi Indonesia berada di bawah Vietnam. 

Data yang dilaporkan The World Economic Forum Swedia (2000), Indonesia memiliki daya saing yang rendah, yaitu hanya menduduki urutan ke-37 dari 57 negara yang disurvei di dunia. Dan masih menurut survai dari lembaga yang sama Indonesia hanya ber-predikat sebagai follower bukan sebagai pemimpin teknologi dari 53 negara di dunia. 

Kualitas pendidikan Indonesia yang rendah itu juga ditunjukkan data Balitbang (2003) bahwa dari 146.052 SD di Indonesia ternyata hanya delapan sekolah saja yang mendapat pengakuan dunia dalam kategori The Primary Years Program (PYP). 

Dari 20.918 SMP di Indonesia ternyata juga hanya delapan sekolah yang mendapat pengakuan dunia dalam kategori The Middle Years Program (MYP) dan dari 8.036 SMA ternyata hanya tujuh sekolah saja yang mendapat pengakuan dunia dalam kategori The Diploma Program (DP). 

Apa makna data-data tentang rendahnya kualitas pendidikan Indonesia itu? 

Maknanya adalah, jelas ada something wrong (masalah) dalam sistem pendidikan Indonesia. Ditinjau secara perspektif ideologis (prinsip) dan perspektif teknis (praktis), berbagai masalah itu dapat dikategorikan dalam 2 (dua) masalah yaitu : 

Pertama, masalah mendasar, yaitu kekeliruan paradigma pendidikan yang mendasari keseluruhan penyelenggaraan sistem pendidikan. 

Kedua, masalah-masalah cabang, yaitu berbagai problem yang berkaitan aspek praktis/teknis yang berkaitan dengan penyelenggaraan pendidikan, seperti :

Mahal-nya biaya pendidikan, rendahnya prestasi siswa, rendahnya sarana fisik, rendahnya kesejahteraan guru, dan sebagainya.

Alhasil  jika pendidikan kita diumpamakan mobil, mobil itu berada di jalan yang salah yang “sampai kapan pun tidak akan pernah menghantarkan kita ke tempat tujuan (masalah mendasar/paradigma).

Di samping salah jalan, mobil itu mengalami kerusakan dan gangguan teknis di sana-sini : bannya kempes, mesinnya bobrok, AC-nya mati, lampu mati, dan jendelanya rusak (masalah cabang/praktis).

Bersambung.

Fisika dan Kepemimpinan

Seri Perkuliahan Fisika dan Teknologi untuk Pemimpin-pemimpin Masa Depan

What Our Next President Needs to Know

Lecture by:

Richard A. Muller

I am a Professor in the Department of Physics at the University of California at Berkeley, and Faculty Senior Scientist at the Lawrence Berkeley Laboratory, where I am also associated with the Institute for Nuclear and Particle Astrophysics.

Kepemimpinan dalam Fisika

(Prof. Yohanes Surya, Ph.D./Rektor Universitas Multimedia Nusantara)

Fenomena Einstein

Pada awal abad kedua puluh, Einstein memperkenalkan teori relativitasnya. Menurut teori ini tidak ada gerak absolut. Semua gerak bersifat relatif (sangat tergantung pada siapa yang mengamatinya). Seorang bisa menganggap gerak suatu pesawat cepat, tapi orang lain bisa menganggap gerak pesawat itu lambat, bahkan ada yang menganggap pesawat itu berhenti.

Sebagai contoh ketika kita berada dalam kereta api yang bergerak, kita melihat seolah-olah pohon-pohon yang terletak di luar kereta bergerak.


Padahal orang yang berdiri dekat pohon itu melihat pohon tidak bergerak. Disini gerak pohon sangat tergantung pada siapa yang mengamatinya.

Pada gerak relativistik ini, mereka yang bergerak paling cepat lah yang paling menonjol. Semua pengamat (kecuali dirinya) akan melihat ia bergerak.

Kondisi relatif ini terjadi pada masyarakat demokrasi dimana setiap orang merasa dirinya paling benar. Tidak ada kebenaran absolut. Dalam suatu organisasi atau perusahaan, kondisi relatif ini terjadi ketika setiap orang dalam organisasi atau perusahan ini merasa dialah yang paling berjasa, paling benar dan paling berhak memimpin.

Dalam kondisi relatif ini akan terdapat banyak oposisi. Oposisi akan selalu menganggap dirinya lebih benar dari lawannya. Mereka berusaha mencari-cari kesalahan lawannya lalu sekali saja ia menemukan kesalahan lawannya, ia langsung menghantamnya.

Amerika adalah contoh keadaan yang mempunyai kondisi relatif. Kita lihat pada pemilihan presiden, yang diutamakan dalam kampanye adalah adu visi. Setiap kandidat mempersiapkan visi masing-masing. Setiap kandidat menganggap bahwa visinyalah yang paling benar.

Pemimpin yang dibutuhkan dan bisa bertahan dalam kondisi ini adalah pemimpin yang mempunyai keunggulan-keunggulan dalam visi, mempunyai integritas tinggi dalam menjalankan visi itu dan mau kerja keras serta bergerak cepat dalam merealisasikan program-program yang
mendukung visi yang unggul itu.

Kecepatan bergerak sangat diperlukan karena mereka terus menerus dipantau oleh oposisi. Integritas sangat perlu, kalau mereka sampai jatuh habislah mereka.


Fenomena Kuantum

Fisika kuantum berkembang secara luar biasa pada abad ke 20. Perkembangan teknologi yang begitu luar biasa saat ini terjadi karena berkembangnya fisika kuantum itu. Walau begitu sampai sekarang orang belum mengerti fenomena kuantum dengan sempurna. Anggap seberkas elektron dilewatkan pada sebuah celah tunggal sempit. Elektron-elektron ini akan tersebar pada layar yang diletakan dibelokkan celah sempit itu. Tiap tempat di layar itu dapat ditempati oleh elektron

Keanehan terjadi ketika hanya satu elektron bergerak mendekati salah satu celah pada celah ganda. Ketika kedua celah terbuka elektron tidak akan menempati bagian pita gelap pada layar. Tapi ketika elektron tepat tiba dicelah, lalu celah yang satunya ditutup tiba-tiba, elektron ternyata dapat menempati bagian pita gelap ini. Kok bisa?




Hal ini membingungkan para fisikawan. Ketika kita menutup celah yang satunya, gerakan kita tidak mengganggu gerakan elektron, tapi mengapa elektron sepertinya tahu bahwa kita menutup celah itu.

Dari peristiwa ini, para fisikawan menyimpulkan bahwa kita tidak bisa menyimpulkan sesuatu sampai suatu eksperimen dilakukan. Dengan kata lain tidak ada kepastian sampai kita membuktikannya dengan eksperimen. Tidak ada yang pasti di alam ini. Segala sesuatu mempunyai kans. Bahkan untuk suatu hal yang mustahilpun ada kans.

Fenomena kuantum ini cocok untuk mereka yang berada pada suasana ketidakpastian yang tinggi. Misalnya pada perusahaan-perusahaan yang bermain dengan resiko atau pada negara yang sedang dalam keadaan kalut akibat perubahan suatu sistem.

Rusia ketika berubah dari negara komunis menjadi negara yang lebih demokratik, mengalami masa-masa ketidakpastian yang sangat tinggi. Rubel menjadi sangat lemah, perekonomian amburadul, percaya diri sebagai bangsa turun drastis. Tidak ada kepastian. Tiap orang berusaha
mencari keuntungannya sendiri. Dalam kondisi seperti ini diperlukan kepemimpinan yang kuat, berani ambil resiko, berspekulasi tapi dengan perhitungan yang cermat dan mampu bertindak tegas. Dengan kepemimpinan seperti ini Putin mampu mengembalikan Rusia menjadi negara yang dihormati lagi dengan perekonomian yang lebih stabil.

Pemimpin yang bisa bertahan dalam situasi yang penuh ketidakpastian ini adalah pemimpin yang kreatif (punya ide-ide dan terobosan-terobosan baru), berani mengimplentasikan pemikiran kreatifnya walau dengan resiko yang tinggi, berani spekulasi tapi didukung dengan perhitungan yang baik, dan bertindak tegas.


(To be Continued)

Fisika untuk Universitas

Fisika untuk Universitas

Ditujukan untuk meningkatkan kualitas proses dan hasil perkuliahan Fisika di tingkat Universitas

Kelistrikan dan Kemagnetan

Topics covered:

Farewell Special
Bring a Friend!

Instructor/speaker: Prof. Walter Lewin

Free Downloads

Video

• iTunes U (MP4 - 103MB)
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  » Download this transcript (PDF)

  Today I would like to talk to you about some of the research that I did during my early days at MIT.

  It's a long time ago.

  I got my Ph.

  D in the Netherlands on nuclear physics and I came over to MIT in 1966.

  I was supposed to be here only for one year.

  I had a one-year postdoc position.

  But I loved it so much I never left.

  I changed fields.

  I joined the research group of Professor Bruno Rossi here at MIT, I changed from nuclear physics to x-ray astronomy.

  X-ray astronomy speaks for itself.

  You're trying to do astronomy in x-rays.

  You cannot see any x-rays from the ground because the earth atmosphere absorbs them completely.

  So you have to go outside the atmosphere unlike optical astronomy and radio astronomy which you can do from the ground.

  When I use the word x-rays I'm thinking of the kind of x-rays that your dentist would be using, medical purposes, about 1 to 50 kilo electron-volts.

  And since all of you took 8.02 you should know by now what a kilo electron volt is.

  Uh, optical light is 2 electron volts, where x-rays, way more energetic than optical light.

  Uh, during the Second World War Wernher von Braun in Peenemunde developed under Hitler Germany destructive rockets.

  They were used to destroy the Allies.

  To destroy you and me.

  And after the war, around 1948, the Americans used these rockets to do science.

  They also got Werner von Braun over to this country and for reasons unknown to me he became a hero.

  They tried to observe x-rays from the solar system.

  And they found indeed that the sun emits x-rays.

  The sun is very close.

  So you may say well that's not a surprise.

  But it's really very unusual because to create x-rays you need extremely high temperatures, which we didn't think existed on the sun.

  And if you take the power that the sun puts out in x-rays, this is joules per second now, and you divide that by the power in the optical and the infrared light of the sun, this symbol stands for sun, that ratio is about 10 to the -7.

  So you must conclude that the sun emits largely optical light and infrared and that the amount of x-rays is a modest byproduct.

  Interesting as it is all by itself.

  In 1962 several scientists here in Cambridge, Massachusetts, among them Bruno Rossi and Riccardo Giacconi and Herb Gursky, made an attempt to observe x-rays from stars outside our solar system.

  The odds were strongly against them.

  The detectors were not sensitive enough.

  If you take the sun and you bring the sun to the nearest stars, which is a distance say of 10 light-years, then there would be no hope that you would be able to detect x-rays from an object like the sun.

  In fact the detectors were too insensitive by about a factor of one billion.

  They tried anyhow and they were successful.

  They did indeed find to everyone's surprise and joy, they found x-rays from at least one object outside the solar system.

  This object was later called SCO X-1.

  SCO stands for the constellation Scorpio in the sky and X for x-rays and 1 for the first source observed in that constellation.

  We now know that this object is a faint blue star.

  And what is extremely special about the object SCO X-1 is that if you take the ratio x-ray power over optical power then that ratio is about 10 to the 3rd.

  Compare that with the sun.

  This object, we had no clue what it was in those days, primarily emit x-rays, and the optical emission is a byproduct.

  Whereas with the sun it is reversed.

  And so the burning question was in those days, what kind of animal is this?

  It must be a totally different beast.

  Something very different from our sun.

  And when I came to MIT in 1966, there were six sources known outside our solar system.

  And they were all discovered with rockets.

  The rockets in those days could spend about five minutes above the earth atmosphere and they would quickly make a scan over the sky, five minutes, that's all they had.

  And I joined the group of uh George Clark, who is still at MIT, uh he was doing x-ray astronomy from very high-flying balloons, very close to the top of the atmosphere, and the advantage of balloons was that you could observe the sky for many, many hours, if you're lucky sometimes even a day or more.

  But on the other hand, since there is always a little bit of atmosphere left above you, even though there's very little, there is still some left, the x-rays are absorbed, almost all x-rays below 20 kilo electron-volts would be absorbed, and we would not be able to see them.

  But of course the compensation was that we could look at the sky for many, many, many hours.

  Nowadays no one is doing these balloon observations anymore.

  No more rocket observations.

  Everything is done of course from satellites.

  So when I came to MIT, together with George Clark, I developed new x-ray detectors for these balloon observations.

  Many graduate students were involved.

  Many undergraduates.

  It would take about two years to build a telescope.

  To give you a rough idea it would take a million dollars in terms of 1966 dollars, and the weight of such a telescope would be roughly 1000 kilograms.

  The balloons in those days would cost about $100,000 to get us up to these high altitudes, and we would need about $80,000 of helium, and you will see some slides of that.

  We have to go to altitudes of about 140000 feet.

  We had huge balloons for that.

  You will see one.

  They have diameters of about 600 feet.

  And the material was polyethylene.

  Extremely thin to make them light-weight so that they can go high.

  The thickness of that polyethylene was about half of one-thousandth of an inch.

  Which is thinner than the saran wrap that you have in the kitchen.

  It is thinner than cigarette paper.

  A very risky business to fly these balloons.

  No guarantee of course that they would work.

  You pay your money.

  If they work that's great.

  If they don't work that's just tough luck.

  There is a good chance that you have a failure when you launch the balloon.

  They're very fragile.

  There could be damage right at the launch.

  But even if they make it up in the atmosphere they have to go through the tropopause, near about a hundred thousand feet where it's very, very cold, the balloons get brittle, and then they can burst.

  And that of course would be the end then of that balloon flight.

  And that could also be the end of a Ph.D thesis.

  Because that all these flights of course were connected with research and therefore with Ph.

  D work and so the tension during these early phases of the launch were always extremely high.

  Sometimes even unbearable.

  So now I would like to show you some slides, which will give you a good idea of what these expeditions were like.

  Oh, yeah, a classic problem.

  This is nice that these -- ah, now they work.

  All right, so if I can have the first slide, you see here Jim and Pat who at the time were undergraduates, they are now both Ph.Ds, and they are working there, very tedious work, trying to put the electronics together.

  You may think that science is not very romantic.

  But I can assure you it is.

  They fell in love.

  They married.

  They have kids.

  And that's the way it sometimes goes in life.

  And so here you see the plant in Texas where these huge balloons were made.

  Uh, balloons are put together sort of like the -- the way that the tangerine is put together.

  At the surface you see these gores of the balloon.

  And the sealing of these gores to make up the balloon were -- was only done by women.

  Only women were allowed to work there.

  Has nothing to do with sex discrimination of any kind.

  It just turned out that women were more patient.

  They did the work better.

  They make way fewer mistakes than men did.

  That's the way it goes sometimes in life.

  Here you see balloon coming out of the box.

  Nicely protected in a plastic cover.

  And we also have here cloth on the -- on the grass because the balloon is so thin that it would certainly get damaged if it touches the grass, it's enormously thin.

  This was not my balloon.

  Uh we were worried that there was something wrong with it.

  You can see here the concern.

  They thought it was a -- there was a hole in the balloon.

  And that if there is a hole in the balloon there's just nothing you can do about it anymore.

  You can't patch it because the hole is almost always through many many layers.

  What you're looking at here is hundreds of layers of balloon that are folded together.

  But as I said, since it wasn't my balloon I wasn't too worried, but of course it's never nice if you see a failure of your colleagues.

  Now I bring you to the desert town Alice Springs in Australia.

  Right at the heart of Australia.

  And now you get a pretty good idea of what it's like.

  Here you see the launch truck.

  The telescope is there.

  And then you see this enormously big balloon.

  All of it is empty now and most of this will stay empty.

  This is the roller arm which holds this part down.

  This is the only part that will be inflated.

  And here you see the helium truck.

  And here you see the inflation tubes.

  And we will let helium in from both sides which will then gradually begin to fill this top part of the balloon.

  And you see here the roller arm in detail.

  The roller arm is very important because when this part of the balloon is being filled it wants to lift, it wants to go up, and of course you have to keep it down, you have to keep it under control.

  And so this roller arm and this -- this car is loaded down with concrete.

  It's very heavy.

  And then just before the launch this roller arm by command is [fweet] flipped over, and then as you will see later then the balloon will make it up.

  And here you see the early part of the inflation.

  Helium comes in from both sides.

  And so we -- we fly these balloons almost always early morning because then the winds are very calm.

  You need extremely reliable winds.

  You need to know the direction very well.

  And the winds should be no more than something like three or four miles per hour.

  If they are stronger you would lose the balloon.

  You see here these gores that I mentioned to you earlier.

  Where the sun is behind the balloon.

  Here the bubble is nearly fully inflated now.

  Here it's still going on.

  Still going on, the inflation.

  But we are very close to the end of the inflation.

  Here is the roller arm and then in this direction here, 500 feet or so down is the payload with the truck.

  We're now very close to a launch.

  We're still in Alice Springs.

  This is -- was my graduate student Jeff McClintock at the time.

  He's now Dr.

  McClintock.

  Here you see radar reflectors which allows us to follow the balloon -- a radar.

  Here you see the telescope hanging on the launch truck.

  Here is the roller arm.

  All this is empty.

  And here you see the parachute.

  We have here a connection between the parachute and the bottom of the balloon.

  And we can control that on radio command.

  We can separate that so that the telescope safely comes back to earth.

  At least that's the idea on paper.

  And so now you see the release of the bubble.

  So the roller arm is up and this bubble now takes off.

  This is an incredibly fantastic moment.

  This is really butterflies in your stomach and ants in your pants.

  This is the moment that balloon can easily fail.

  Very thin material, the helium goes up, reflects against the top, is pushed back again, you get this peculiar mushroom shape, it makes an enormous sound like a storm.

  The idea now is that this balloon will go higher and higher in the sky.

  Will pick up all this empty part.

  This is not inflated.

  As the balloon goes up in the atmosphere the atmospheric pressure will go down.

  And the helium will expand and will fill the balloon.

  And the -- the trick now is for this truck to manipulate, to maneuver itself under what we call the bubble.

  And therefore the wind has to be in this direction so that the balloon comes to the truck.

  And then the truck tries to get straight under the balloon.

  And then the payload will be released here.

  Here you see a close-up of this mushroom.

  You can actually see this reflection of the helium going up and coming back.

  You can also see these gores very clearly.

  It's tedious work.

  By these women who have to seal these balloons.

  Enormous amount of labor goes into it.

  Amount of helium as I said earlier is about $80,000.

  About the same price of the balloon.

  And here it goes higher.

  We're in Alice Springs.

  The cover is falling off.

  Balloon is going up.

  See the engine is already running.

  The truck cannot move yet because if it started to move this part of the balloon would slide over the cloth.

  There would be friction and there would be holes in the balloon.

  So this truck has to wait until all of this is off the ground.

  Going higher.

  And I'm now so close to the balloon that I couldn't continue my picture-taking from Alice Springs.

  So I will jump back to an earlier flight in the United States.

  We flew these balloons in the United States from a town called Palestine, Texas.

  And so you will see then the remaining part of the flight from Palestine, Texas.

  So the balloon is now completely off the ground.

  See a little bit of gas, well it's not so little, but it looks very little compared to the size of this balloon.

  You see the parachute here and here then is the connection which on radio command we can separate.

  So now this is a very crucial moment.

  The person in charge on this launch truck has probably driven the truck to get straight under the balloon.

  And when it's straight under there they will allow the payload to go free.

  The payload is attached to this truck.

  If the balloon is too far ahead and the payload is released it will pendulum into the ground.

  And if you release it too early then of course the payload will pendulum back into the launch truck.

  Both would be a disaster.

  If the pull of the balloon is not enough, for instance if a hole developed during the launch, so if the tension is not strong enough, you would release the payload, it would go bang, back to the ground.

  So all these factors have to be taken into account, and then finally the person in charge commits to a launch.

  And then there it goes.

  All the way empty.

  Here you see the helium.

  The parachute.

  And you see the -- the payload.

  And here you see the balloon at 150000 feet, 45 kilometers high in the sky.

  The helium has now expanded.

  The balloon is fully inflated.

  And you can look straight through it.

  It's only half of one-thousandth of an inch of polyethylene.

  And these are huge ducts which have openings of about ten meters each.

  And they are there because the balloon cannot stand any over-pressure.

  If there is any over-pressure the balloon would pop and so when the balloon keeps rising and rising and rising when it reaches -- reaches its maximum volume the helium would escape at the bottom.

  That's the idea of these ducts.

  Here you see George Ricker who was graduate student, my graduate student at the time.

  This is in Australia.

  He is now Dr.

  Ricker.

  He's still at MIT.

Pengembangan Perkuliahan

1. Buatlah sebuah Esai mengenai materi perkuliahan ini

2. Buatlah sebuah kelompok berjumlah 5 orang untuk menganalisis materi perkuliahan ini

3. Lakukan Penelitian Sederhana dengan kelompok tersebut

4. Hasilkan sebuah produk yang dapat digunakan oleh masyarakat

5. Kembangkan produk tersebut dengan senantiasa meningkatkan kualitasnya

Ucapan Terima Kasih Kepada:

1. Para Dosen MIT di Departemen Fisika

a. Prof. Walter Lewin, Ph.D.

(http://web.mit.edu/physics/people/faculty/lewin_walter.html)

b. Prof. Bernd Surrow, Ph.D.

(http://web.mit.edu/physics/people/faculty/surrow_bernd.html)

Staff

Visualizations:
Prof. John Belcher

Instructors:
Dr. Peter Dourmashkin
Prof. Bruce Knuteson
Prof. Gunther Roland
Prof. Bolek Wyslouch
Dr. Brian Wecht
Prof. Eric Katsavounidis
Prof. Robert Simcoe
Prof. Joseph Formaggio

Course Co-Administrators:
Dr. Peter Dourmashkin
Prof. Robert Redwine

Technical Instructors:
Andy Neely
Matthew Strafuss

Course Material:
Dr. Peter Dourmashkin
Prof. Eric Hudson
Dr. Sen-Ben Liao

Acknowledgements

The TEAL project is supported by The Alex and Brit d'Arbeloff Fund for Excellence in MIT Education, MIT iCampus, the Davis Educational Foundation, the National Science Foundation, the Class of 1960 Endowment for Innovation in Education, the Class of 1951 Fund for Excellence in Education, the Class of 1955 Fund for Excellence in Teaching, and the Helena Foundation. Many people have contributed to the development of the course materials. (PDF)

2. Para Dosen Pendidikan Fisika, FPMIPA, Universitas Pendidikan Indonesia.

Terima Kasih Semoga Bermanfaat dan mohon Maaf apabila ada kesalahan.