Sabtu, 17 Januari 2009

[FISIKA] Digest Number 2645

Messages In This Digest (10 Messages)

Messages

1.

Kuliah Fisika Gratis dari Universitas AS

Posted by: "yulianto_mohsin" moyas@mac.com   yulianto_mohsin

Thu Jan 15, 2009 9:46 pm (PST)

Salam rekan-rekan milis Fisika Indonesia,

Dengan menjamurnya iPod sejak 5 tahun lalu, toko musik iTunes juga
ngga kalah tenar. Sekitar 1-2 tahun yang lalu, iTunes meluncurkan
iTunesU yang berisi khusus podcast kuliah-kuliah yang disediakan
gratis untuk diunduh (download) dari berbagai universitas di Amerika.
Podcast ini kuliah yang direkam dan tersedia dalam bentuk audio dan
siapa saja boleh mengunduhnya. Untuk mendengarkannya tidak perlu iPod,
cukup pakai iTunes.

Software iTunes dapat diunduh di http://www.apple.com/itunes/ dan
tersedia untuk dua macam platform PC dan Mac.

Saya sudah memanfaatkan berbagai podcast pembelajaran pelbagai macam
mata kuliah dan saya ingin rekan-rekan juga menikmati podcasts ini.

Untuk pelajaran fisika, ada beberapa seri podcast, diantaranya:
1. MIT 8.01 Physics I: Classical Mechanics oleh Prof. Walter Lewin.
2. MIT 8.02 Physics II: Electricity and Magnetism oleh Prof. Walter Lewin
3. MIT 8.03 Physics III: Vibrations & Waves oleh Prof. Walter Lewin
4. Modern Theoretical Physics oleh Prof. Leonard Susskind dari
Stanford University.
5. Modern Physics: The Theoretical Minimum oleh Prof. Leonard Susskind
dari Stanford University.

Salam hangat,
Yulianto Mohsin

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2.

Seminar Sains dan Pendidikan Juni 2009 di UKSW Salatiga

Posted by: "wahyu hari kristiyanto" whkris_fisika@yahoo.com   whkris_fisika

Thu Jan 15, 2009 10:01 pm (PST)



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3.

Fwd: saya berhasil membuat interferometer michelson

Posted by: "Dan" di2003@alumni.soton.ac.uk   dit78er

Thu Jan 15, 2009 10:11 pm (PST)

---------- Forwarded message ----------
From: Kartijo Dewantoro <dkartijo@yahoo.co.id>
Date: 2009/1/15
Subject: saya berhasil membuat interferometer michelson
To: fisika_indonesia Moderator <fisika_indonesia-owner@yahoogroups.com>

saya pendatang baru di sini. Selama dua tahun lebih saya mengembangkan alat
interferometer dan alah satu yang sudah saya buat adalah interferometer
michelson. Selama ini pendidikan di sekolah (SMU), terutama kelas 3IPA,
pembahasan tentang interferensi masih bersifat abstrak. Sejak saya masih
sekolah bahkan sampai diperguruan tinggi, interfeensi yang diajarkan dikelas
masih belum ke fenomenanya, kecuali hal-hal yang biasa di temui misalnya
interferensi pada lapisan tipis... Saya sudah berhasil membuat
interferometer sederhana yang bukan saja interferometr YOUNG, tetapi
Interferometer Michelson di mana dalam alat ini ada yang disebut sebagai *
beamplitter. *Beamsplitter yang saya gunakan jangan dibayangkan seperti
buatan pabrik, tapi jauh dari itu. Meski demikian hasil yang diperoleh
sangat menakjubkan. Mohon bantuan saran atau ide tentang apa yang telah saya
lakukan. Sebenarnya saya alat yang saya buat ini dapat dimanfaatkan di
sekolah -sekolah. Thanks.....

--- Pada *Rab, 14/1/09, fisika_indonesia Moderator <
fisika_indonesia-owner@yahoogroups.com>* menulis:

Dari: fisika_indonesia Moderator <fisika_indonesia-owner@yahoogroups.com>
Topik: File - join.txt
Kepada: dkartijo@yahoo.co.id
Tanggal: Rabu, 14 Januari, 2009, 4:37 PM


************************************
* MILIS FISIKA INDONESIA *
************************************

Selamat datang !!!
Welcome !!!
Herzlich willkommen !!!

Milis Fisika Indonesia (MFI) dirintis oleh 18 fisikawan Indonesia di LN,
terbanyak di Eropa. MFI dikelola oleh Himpunan Fisika Indonesia (HFI) Cabang LN,
yang saat ini berpusat di Hannover.
Medium ini dimaksudkan untuk kontak dan diskusi antar ilmuwan, pengguna, dan
pemerhati fisika.
Berbagai aspek fisika dapat dibahas di sini:

- fisika murni, baik teori maupun eksperimen.

- fisika terapan, baik teori maupun eksperimen, termasuk elektronika,
instrumentasi mau pun ilmu-ilmu teknik dan teknologi terpadu.

- manajemen fisika (pendidikan, organisasi
dan kontak), termasuk info dan diskusi seputar alat-alat bantu fisika seperti
ilmu komputer (software/hardware), statistika dan matematika.

Agar milis ini dapat berlanjut dengan lebih baik dan efisien, diharapkan
memperhatikan aturan-aturan/etiket yang berlaku.

Selamat Berdikusi,

Tim Moderator
__________________________________________________________
Aturan Pengiriman Email:

1. Hendaknya HANYA mengirimkan mail yang berhubungan dengan Ilmu
FISIKA & APLIKASINYA.

2.CANTUMKAN judul subject dengan jelas sehingga memudahkan
pengenalan isi dari mail yang dikirim (CONTOH: Subyek email seperti
"hello", "mohon bantuan" dsb harap DIHINDARI). Pada bagian
akhir mail
CANTUMKAN nama pengirim berikut latar pendidikan bila perlu.

3. Harap MENGHAPUS bagian mail yang dinilai tidak perlu pada saat
me-reply seperti:
- footer iklan YahooGroups.
- message yang tidak berhubungan subjectnya dengan yang direply.

4.Dianjurkan TIDAK mengirim attachment, khususnya attachment file dalam ukuran
besar. Apabila ada file yang hendak disharingkan, sebaiknya di-upload
kehttp://groups.yahoo.com/group/fisika_indonesia/files

DAN

5. DILARANG KERAS MENGIRIM EMAIL YANG BERISIKAN SARA, P0RNOGRAFI, KATA-KATA
KASAR, EMAIL BERANTAI, MONEY GAME, MLM, JUALAN DAN SEJENISNYA. YANG MELANGGAR
AKAN DIKELUARKAN DARI MILIS, DENGAN CARA APAPUN YANG DIPILIH TIM MODERATOR PADA
SAAT ITU :-)...
__________________________________________________________

------------------------------
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4.

Fwd: [MKI] International Workshop on Advanced Material for New and R

Posted by: "Dan" di2003@alumni.soton.ac.uk   dit78er

Thu Jan 15, 2009 11:24 pm (PST)

---------- Forwarded message ----------
From: Fisika LIPI <fisika@mail.lipi.go.id>
Date: 2009/1/16
Subject: [MKI] International Workshop on Advanced Material for New and
Renewable Energy
To: mki@milis.opi.lipi.go.id

The International Workshop on Advanced Material for New and Renewable Energy
is organized by Research Center for Physics, Indonesian Institute of
Sciences (LIPI), in co-operation with ASEAN Sub Committee on Material
Science and Technology (SCMST) and Sub Committee on Non-Conventional Energy
Research (SCNCER). Its primary objective is to provide an effective media
for sharing of information about research in material for energy and its
application. This event is also of importance for creating network,
collecting and coordinating information, so that research planners in this
area are able to avoid double or redundant experiment.

Developing advanced energy technologies requires more than applied research
and development. Basic research in advanced material for new and renewable
energy will be the foundation for progress on energy technologies with zero
pollution. Electricity storage, solar cells, fuel cells, hydrogen production
and storage just a few examples. It is creative linkages between basic
research and applied technology development that will pinpoint these
opportunities.

This event also has aim to encourage member country and the rest of the
world whose concern in Climate Change and Global Warming as a world issue to
find a feasible solution for this matter.

Info :
http://www.opi.lipi.go.id/situs/amnre2009/

---
Organizer of AMNRE 2009
amnre2009@mail.lipi.go.id

_______________________________________________
Masyarakat Komputasi Indonesia - MKI
http://www.opi.lipi.go.id/situs/mki/
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5a.

Bls: [FISIKA] Fwd: saya berhasil membuat interferometer michelson

Posted by: "Mariano Nathanael" mariano_nathanael@yahoo.co.id   mariano_nathanael

Thu Jan 15, 2009 11:38 pm (PST)

Untuk Dan
Kasi fotonya dong atau gambarnya dan bagaimana car membuatnya, kalo bisa harganya juga. Saya sangat tertrik dengan alat ini. makasih

________________________________
Dari: Dan <di2003@alumni.soton.ac.uk>
Kepada: fisika_indonesia@yahoogroups.com
Terkirim: Jumat, 16 Januari, 2009 13:11:06
Topik: [FISIKA] Fwd: saya berhasil membuat interferometer michelson

---------- Forwarded message ----------
From: Kartijo Dewantoro <dkartijo@yahoo. co.id>
Date: 2009/1/15
Subject: saya berhasil membuat interferometer michelson
To: fisika_indonesia Moderator <fisika_indonesia- owner@yahoogroup s.com>

saya pendatang baru di sini. Selama dua tahun lebih saya mengembangkan alat interferometer dan alah satu yang sudah saya buat adalah interferometer michelson. Selama ini pendidikan di sekolah (SMU), terutama kelas 3IPA, pembahasan tentang interferensi masih bersifat abstrak. Sejak saya masih sekolah bahkan sampai diperguruan tinggi, interfeensi yang diajarkan dikelas masih belum ke fenomenanya, kecuali hal-hal yang biasa di temui misalnya interferensi pada lapisan tipis... Saya sudah berhasil membuat interferometer sederhana yang bukan saja interferometr YOUNG, tetapi Interferometer Michelson di mana dalam alat ini ada yang disebut sebagai beamplitter. Beamsplitter yang saya gunakan jangan dibayangkan seperti buatan pabrik, tapi jauh dari itu. Meski demikian hasil yang diperoleh sangat menakjubkan. Mohon bantuan saran atau ide tentang apa yang telah saya lakukan. Sebenarnya saya alat yang saya buat ini dapat dimanfaatkan di sekolah -sekolah.
Thanks.....

--- Pada Rab, 14/1/09, fisika_indonesia Moderator <fisika_indonesia- owner@yahoogroup s.com> menulis:

Dari: fisika_indonesia Moderator <fisika_indonesia- owner@yahoogroup s.com>
Topik: File - join.txt
Kepada: dkartijo@yahoo. co.id
Tanggal: Rabu, 14 Januari, 2009, 4:37 PM

************ ********* ********* ******
* MILIS FISIKA INDONESIA *
************ ********* ********* ******

Selamat datang !!!
Welcome !!!
Herzlich willkommen !!!

Milis Fisika Indonesia (MFI) dirintis oleh 18 fisikawan Indonesia di LN,
terbanyak di Eropa. MFI dikelola oleh Himpunan Fisika Indonesia (HFI) Cabang LN,
yang saat ini berpusat di Hannover.
Medium ini dimaksudkan untuk kontak dan diskusi antar ilmuwan, pengguna, dan
pemerhati fisika.
Berbagai aspek fisika dapat dibahas di sini:

- fisika murni, baik teori maupun eksperimen.

- fisika terapan, baik teori maupun eksperimen, termasuk elektronika,
instrumentasi mau pun ilmu-ilmu teknik dan teknologi terpadu.

- manajemen fisika (pendidikan, organisasi
dan kontak), termasuk info dan diskusi seputar alat-alat bantu fisika seperti
ilmu komputer (software/hardware) , statistika dan matematika.

Agar milis ini dapat berlanjut dengan lebih baik dan efisien, diharapkan
memperhatikan aturan-aturan/ etiket yang berlaku.

Selamat Berdikusi,

Tim Moderator
____________ _________ _________ _________ _________ _________ ________
Aturan Pengiriman Email:

1. Hendaknya HANYA mengirimkan mail yang berhubungan dengan Ilmu
FISIKA & APLIKASINYA.

2.CANTUMKAN judul subject dengan jelas sehingga memudahkan
pengenalan isi dari mail yang dikirim (CONTOH: Subyek email seperti
"hello", "mohon bantuan" dsb harap DIHINDARI). Pada bagian
akhir mail
CANTUMKAN nama pengirim berikut latar pendidikan bila perlu.

3. Harap MENGHAPUS bagian mail yang dinilai tidak perlu pada saat
me-reply seperti:
- footer iklan YahooGroups.
- message yang tidak berhubungan subjectnya dengan yang direply.

4.Dianjurkan TIDAK mengirim attachment, khususnya attachment file dalam ukuran
besar. Apabila ada file yang hendak disharingkan, sebaiknya di-upload ke
http://groups. yahoo.com/ group/fisika_ indonesia/ files

DAN

5. DILARANG KERAS MENGIRIM EMAIL YANG BERISIKAN SARA, P0RNOGRAFI, KATA-KATA
KASAR, EMAIL BERANTAI, MONEY GAME, MLM, JUALAN DAN SEJENISNYA. YANG MELANGGAR
AKAN DIKELUARKAN DARI MILIS, DENGAN CARA APAPUN YANG DIPILIH TIM MODERATOR PADA
SAAT ITU :-)...
____________ _________ _________ _________ _________ _________ ________

________________________________
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5b.

Bls: [FISIKA] Fwd: saya berhasil membuat interferometer michelson

Posted by: "Kartijo Dewantoro" dkartijo@yahoo.co.id   dkartijo

Fri Jan 16, 2009 8:50 am (PST)

Dalam waktu dekat foto alat dan hasil percobaannya akan saya bagikan buat temen-temen fisika....Wah kalo masalah harga saya jadi bingung nie ngomongnya........Tapi satu hal yang saya inginkan agar alat ini dapat dipakai sebagai media pembelajaran di sekolah SMU. Satu kenyataan yang tidak dapat dipungkiri, interferometer michelson merupakan alat yang digunakan Michelson (juga Morley) lebih dari 2 abad lalu dalam upayanya memburu ETER.....dan dari percobaan itulah diperoleh kesimpulan negatif tentang ETER yang sebelumnya dianggap sebagai medium yang mengisi seluruh alam tak terkecuali medium bagi gelombang elektromagnet cahaya......Bayangkan! percobaan yang begitu penting dalam sejarah perkembangan ilmu fisika yang sekarang merupakan materi pelajaran fisika SMA tidak pernah dilakukan. Di sisi lain, alat ini juga dapat menunjukkan bagaimana dua berkas cahaya koheren (saya menggunakan laser pointer murah sbg sumbernya) bertemu dan berinteraksi
(berinterferensi) dan menghasilkan pola berupa lingkaran-lingkaran kosentris gelap-terang....pola tsb terus bergerak (sensitif terhadap getaran, bahkan getaran yang kecil pun dapat terdeteksi)....sungguh menarik menampilkan fenomena fisika diman selama ini hanya dapat dibayangkan oleh siswa...dan inilah yag pernah saya lakukan ketika saya mengajar fisika...para siswa melihat secara langsung proses terjadinya interferensi.....

--- Pada Jum, 16/1/09, Mariano Nathanael <mariano_nathanael@yahoo.co.id> menulis:
Dari: Mariano Nathanael <mariano_nathanael@yahoo.co.id>
Topik: Bls: [FISIKA] Fwd: saya berhasil membuat interferometer michelson
Kepada: fisika_indonesia@yahoogroups.com
Tanggal: Jumat, 16 Januari, 2009, 6:43 AM

Untuk Dan
Kasi fotonya dong atau gambarnya dan bagaimana car membuatnya, kalo bisa harganya juga. Saya sangat tertrik dengan alat ini. makasih
Dari: Dan <di2003@alumni. soton.ac. uk>
Kepada: fisika_indonesia@ yahoogroups. com
Terkirim: Jumat, 16 Januari, 2009 13:11:06
Topik: [FISIKA] Fwd: saya berhasil membuat interferometer michelson

---------- Forwarded message ----------
From: Kartijo Dewantoro <dkartijo@yahoo. co.id>
Date: 2009/1/15
Subject: saya berhasil membuat interferometer michelson
To: fisika_indonesia Moderator <fisika_indonesia- owner@yahoogroup s.com>

saya pendatang baru  di sini. Selama dua tahun lebih saya mengembangkan alat interferometer dan alah satu yang sudah saya buat adalah interferometer michelson. Selama ini pendidikan di sekolah (SMU), terutama kelas 3IPA, pembahasan tentang interferensi masih  bersifat abstrak. Sejak saya masih sekolah bahkan sampai diperguruan tinggi, interfeensi yang diajarkan dikelas masih  belum  ke fenomenanya, kecuali hal-hal yang biasa di temui misalnya interferensi pada lapisan tipis... Saya sudah berhasil membuat interferometer sederhana yang bukan saja interferometr YOUNG, tetapi  Interferometer Michelson  di mana dalam alat ini ada yang disebut sebagai beamplitter. Beamsplitter yang saya gunakan jangan dibayangkan seperti buatan pabrik, tapi jauh dari itu. Meski demikian hasil yang diperoleh sangat menakjubkan. Mohon bantuan saran atau ide tentang apa yang telah saya lakukan. Sebenarnya saya alat yang saya buat ini dapat dimanfaatkan di sekolah
-sekolah. Thanks.....

--- Pada Rab, 14/1/09, fisika_indonesia Moderator <fisika_indonesia- owner@yahoogroup s.com> menulis:
Dari: fisika_indonesia Moderator <fisika_indonesia- owner@yahoogroup s.com>
Topik: File - join.txt
Kepada: dkartijo@yahoo. co.id
Tanggal: Rabu, 14 Januari, 2009, 4:37 PM


************ ********* ********* ******
* MILIS FISIKA INDONESIA *
************ ********* ********* ******

Selamat datang !!!
Welcome !!!
Herzlich willkommen !!!

Milis Fisika Indonesia (MFI) dirintis oleh 18 fisikawan Indonesia di LN,
terbanyak di Eropa. MFI dikelola oleh Himpunan Fisika Indonesia (HFI) Cabang LN,
yang saat ini berpusat di Hannover.
Medium ini dimaksudkan untuk kontak dan diskusi antar ilmuwan, pengguna, dan
pemerhati fisika.
Berbagai aspek fisika dapat dibahas di sini:

- fisika murni, baik teori maupun eksperimen.

- fisika terapan, baik teori maupun eksperimen, termasuk elektronika,
instrumentasi mau pun ilmu-ilmu teknik dan teknologi terpadu.

- manajemen fisika (pendidikan, organisasi
dan kontak), termasuk info dan diskusi seputar alat-alat bantu fisika seperti
ilmu komputer (software/hardware) , statistika dan matematika.

Agar milis ini dapat berlanjut dengan lebih baik dan efisien, diharapkan
memperhatikan aturan-aturan/ etiket yang berlaku.

Selamat Berdikusi,

Tim Moderator
____________ _________ _________ _________ _________ _________ ________
Aturan Pengiriman Email:

1. Hendaknya HANYA mengirimkan mail yang berhubungan dengan Ilmu
FISIKA & APLIKASINYA.

2.CANTUMKAN judul subject dengan jelas sehingga memudahkan
pengenalan isi dari mail yang dikirim (CONTOH: Subyek email seperti
"hello", "mohon bantuan" dsb harap DIHINDARI). Pada bagian
akhir mail
CANTUMKAN nama pengirim berikut latar pendidikan bila perlu.

3. Harap MENGHAPUS bagian mail yang dinilai tidak perlu pada saat
me-reply seperti:
- footer iklan YahooGroups.
- message yang tidak berhubungan subjectnya dengan yang direply.

4.Dianjurkan TIDAK mengirim attachment, khususnya attachment file dalam ukuran
besar. Apabila ada file yang hendak disharingkan, sebaiknya di-upload ke
http://groups. yahoo.com/ group/fisika_ indonesia/ files

DAN

5. DILARANG KERAS MENGIRIM EMAIL YANG BERISIKAN SARA, P0RNOGRAFI, KATA-KATA
KASAR, EMAIL BERANTAI, MONEY GAME, MLM, JUALAN DAN SEJENISNYA. YANG MELANGGAR
AKAN DIKELUARKAN DARI MILIS, DENGAN CARA APAPUN YANG DIPILIH TIM MODERATOR PADA
SAAT ITU :-)...
____________ _________ _________ _________ _________ _________ ________

Nikmati chatting lebih sering di blog dan situs web
Gunakan Wizard Pembuat Pingbox Online

Menambah banyak teman sangatlah mudah dan cepat.
Undang teman dari Hotmail, Gmail ke Yahoo! Messenger sekarang!

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6.

Our world may be a giant hologram

Posted by: "dit78er" di2003@alumni.soton.ac.uk   dit78er

Fri Jan 16, 2009 2:00 am (PST)

http://www.newscientist.com/article/mg20126911.300-our-world-may-be-a-giant-hologram.html?full=true

Our world may be a giant hologram

15 January 2009 by Marcus Chown

DRIVING through the countryside south of Hanover, it would be easy to
miss the GEO600 experiment. From the outside, it doesn't look much: in
the corner of a field stands an assortment of boxy temporary
buildings, from which two long trenches emerge, at a right angle to
each other, covered with corrugated iron. Underneath the metal sheets,
however, lies a detector that stretches for 600 metres.

For the past seven years, this German set-up has been looking for
gravitational waves - ripples in space-time thrown off by super-dense
astronomical objects such as neutron stars and black holes. GEO600 has
not detected any gravitational waves so far, but it might
inadvertently have made the most important discovery in physics for
half a century.

For many months, the GEO600 team-members had been scratching their
heads over inexplicable noise that is plaguing their giant detector.
Then, out of the blue, a researcher approached them with an
explanation. In fact, he had even predicted the noise before he knew
they were detecting it. According to Craig Hogan, a physicist at the
Fermilab particle physics lab in Batavia, Illinois, GEO600 has
stumbled upon the fundamental limit of space-time - the point where
space-time stops behaving like the smooth continuum Einstein described
and instead dissolves into "grains", just as a newspaper photograph
dissolves into dots as you zoom in. "It looks like GEO600 is being
buffeted by the microscopic quantum convulsions of space-time," says
Hogan.

If this doesn't blow your socks off, then Hogan, who has just been
appointed director of Fermilab's Center for Particle Astrophysics, has
an even bigger shock in store: "If the GEO600 result is what I suspect
it is, then we are all living in a giant cosmic hologram."

The idea that we live in a hologram probably sounds absurd, but it is
a natural extension of our best understanding of black holes, and
something with a pretty firm theoretical footing. It has also been
surprisingly helpful for physicists wrestling with theories of how the
universe works at its most fundamental level.

The holograms you find on credit cards and banknotes are etched on
two-dimensional plastic films. When light bounces off them, it
recreates the appearance of a 3D image. In the 1990s physicists
Leonard Susskind and Nobel prizewinner Gerard 't Hooft suggested that
the same principle might apply to the universe as a whole. Our
everyday experience might itself be a holographic projection of
physical processes that take place on a distant, 2D surface.

The "holographic principle" challenges our sensibilities. It seems
hard to believe that you woke up, brushed your teeth and are reading
this article because of something happening on the boundary of the
universe. No one knows what it would mean for us if we really do live
in a hologram, yet theorists have good reasons to believe that many
aspects of the holographic principle are true.

Susskind and 't Hooft's remarkable idea was motivated by
ground-breaking work on black holes by Jacob Bekenstein of the Hebrew
University of Jerusalem in Israel and Stephen Hawking at the
University of Cambridge. In the mid-1970s, Hawking showed that black
holes are in fact not entirely "black" but instead slowly emit
radiation, which causes them to evaporate and eventually disappear.
This poses a puzzle, because Hawking radiation does not convey any
information about the interior of a black hole. When the black hole
has gone, all the information about the star that collapsed to form
the black hole has vanished, which contradicts the widely affirmed
principle that information cannot be destroyed. This is known as the
black hole information paradox.

Bekenstein's work provided an important clue in resolving the paradox.
He discovered that a black hole's entropy - which is synonymous with
its information content - is proportional to the surface area of its
event horizon. This is the theoretical surface that cloaks the black
hole and marks the point of no return for infalling matter or light.
Theorists have since shown that microscopic quantum ripples at the
event horizon can encode the information inside the black hole, so
there is no mysterious information loss as the black hole evaporates.

Crucially, this provides a deep physical insight: the 3D information
about a precursor star can be completely encoded in the 2D horizon of
the subsequent black hole - not unlike the 3D image of an object being
encoded in a 2D hologram. Susskind and 't Hooft extended the insight
to the universe as a whole on the basis that the cosmos has a horizon
too - the boundary from beyond which light has not had time to reach
us in the 13.7-billion-year lifespan of the universe. What's more,
work by several string theorists, most notably Juan Maldacena at the
Institute for Advanced Study in Princeton, has confirmed that the idea
is on the right track. He showed that the physics inside a
hypothetical universe with five dimensions and shaped like a Pringle
is the same as the physics taking place on the four-dimensional boundary.

According to Hogan, the holographic principle radically changes our
picture of space-time. Theoretical physicists have long believed that
quantum effects will cause space-time to convulse wildly on the
tiniest scales. At this magnification, the fabric of space-time
becomes grainy and is ultimately made of tiny units rather like
pixels, but a hundred billion billion times smaller than a proton.
This distance is known as the Planck length, a mere 10-35 metres. The
Planck length is far beyond the reach of any conceivable experiment,
so nobody dared dream that the graininess of space-time might be
discernable.

That is, not until Hogan realised that the holographic principle
changes everything. If space-time is a grainy hologram, then you can
think of the universe as a sphere whose outer surface is papered in
Planck length-sized squares, each containing one bit of information.
The holographic principle says that the amount of information papering
the outside must match the number of bits contained inside the volume
of the universe.

Since the volume of the spherical universe is much bigger than its
outer surface, how could this be true? Hogan realised that in order to
have the same number of bits inside the universe as on the boundary,
the world inside must be made up of grains bigger than the Planck
length. "Or, to put it another way, a holographic universe is blurry,"
says Hogan.

This is good news for anyone trying to probe the smallest unit of
space-time. "Contrary to all expectations, it brings its microscopic
quantum structure within reach of current experiments," says Hogan. So
while the Planck length is too small for experiments to detect, the
holographic "projection" of that graininess could be much, much
larger, at around 10-16 metres. "If you lived inside a hologram, you
could tell by measuring the blurring," he says.

When Hogan first realised this, he wondered if any experiment might be
able to detect the holographic blurriness of space-time. That's where
GEO600 comes in.

Gravitational wave detectors like GEO600 are essentially fantastically
sensitive rulers. The idea is that if a gravitational wave passes
through GEO600, it will alternately stretch space in one direction and
squeeze it in another. To measure this, the GEO600 team fires a single
laser through a half-silvered mirror called a beam splitter. This
divides the light into two beams, which pass down the instrument's
600-metre perpendicular arms and bounce back again. The returning
light beams merge together at the beam splitter and create an
interference pattern of light and dark regions where the light waves
either cancel out or reinforce each other. Any shift in the position
of those regions tells you that the relative lengths of the arms has
changed.

"The key thing is that such experiments are sensitive to changes in
the length of the rulers that are far smaller than the diameter of a
proton," says Hogan.

So would they be able to detect a holographic projection of grainy
space-time? Of the five gravitational wave detectors around the world,
Hogan realised that the Anglo-German GEO600 experiment ought to be the
most sensitive to what he had in mind. He predicted that if the
experiment's beam splitter is buffeted by the quantum convulsions of
space-time, this will show up in its measurements (Physical Review D,
vol 77, p 104031). "This random jitter would cause noise in the laser
light signal," says Hogan.

In June he sent his prediction to the GEO600 team. "Incredibly, I
discovered that the experiment was picking up unexpected noise," says
Hogan. GEO600's principal investigator Karsten Danzmann of the Max
Planck Institute for Gravitational Physics in Potsdam, Germany, and
also the University of Hanover, admits that the excess noise, with
frequencies of between 300 and 1500 hertz, had been bothering the team
for a long time. He replied to Hogan and sent him a plot of the noise.
"It looked exactly the same as my prediction," says Hogan. "It was as
if the beam splitter had an extra sideways jitter."
Incredibly, the experiment was picking up unexpected noise - as if
quantum convulsions were causing an extra sideways jitter

No one - including Hogan - is yet claiming that GEO600 has found
evidence that we live in a holographic universe. It is far too soon to
say. "There could still be a mundane source of the noise," Hogan admits.

Gravitational-wave detectors are extremely sensitive, so those who
operate them have to work harder than most to rule out noise. They
have to take into account passing clouds, distant traffic,
seismological rumbles and many, many other sources that could mask a
real signal. "The daily business of improving the sensitivity of these
experiments always throws up some excess noise," says Danzmann. "We
work to identify its cause, get rid of it and tackle the next source
of excess noise." At present there are no clear candidate sources for
the noise GEO600 is experiencing. "In this respect I would consider
the present situation unpleasant, but not really worrying."

For a while, the GEO600 team thought the noise Hogan was interested in
was caused by fluctuations in temperature across the beam splitter.
However, the team worked out that this could account for only
one-third of the noise at most.

Danzmann says several planned upgrades should improve the sensitivity
of GEO600 and eliminate some possible experimental sources of excess
noise. "If the noise remains where it is now after these measures,
then we have to think again," he says.

If GEO600 really has discovered holographic noise from quantum
convulsions of space-time, then it presents a double-edged sword for
gravitational wave researchers. One on hand, the noise will handicap
their attempts to detect gravitational waves. On the other, it could
represent an even more fundamental discovery.

Such a situation would not be unprecedented in physics. Giant
detectors built to look for a hypothetical form of radioactivity in
which protons decay never found such a thing. Instead, they discovered
that neutrinos can change from one type into another - arguably more
important because it could tell us how the universe came to be filled
with matter and not antimatter (New Scientist, 12 April 2008, p 26).

It would be ironic if an instrument built to detect something as vast
as astrophysical sources of gravitational waves inadvertently detected
the minuscule graininess of space-time. "Speaking as a fundamental
physicist, I see discovering holographic noise as far more
interesting," says Hogan.
Small price to pay

Despite the fact that if Hogan is right, and holographic noise will
spoil GEO600's ability to detect gravitational waves, Danzmann is
upbeat. "Even if it limits GEO600's sensitivity in some frequency
range, it would be a price we would be happy to pay in return for the
first detection of the graininess of space-time." he says. "You bet we
would be pleased. It would be one of the most remarkable discoveries
in a long time."

However Danzmann is cautious about Hogan's proposal and believes more
theoretical work needs to be done. "It's intriguing," he says. "But
it's not really a theory yet, more just an idea." Like many others,
Danzmann agrees it is too early to make any definitive claims. "Let's
wait and see," he says. "We think it's at least a year too early to
get excited."

The longer the puzzle remains, however, the stronger the motivation
becomes to build a dedicated instrument to probe holographic noise.
John Cramer of the University of Washington in Seattle agrees. It was
a "lucky accident" that Hogan's predictions could be connected to the
GEO600 experiment, he says. "It seems clear that much better
experimental investigations could be mounted if they were focused
specifically on the measurement and characterisation of holographic
noise and related phenomena."

One possibility, according to Hogan, would be to use a device called
an atom interferometer. These operate using the same principle as
laser-based detectors but use beams made of ultracold atoms rather
than laser light. Because atoms can behave as waves with a much
smaller wavelength than light, atom interferometers are significantly
smaller and therefore cheaper to build than their
gravitational-wave-detector counterparts.

So what would it mean it if holographic noise has been found? Cramer
likens it to the discovery of unexpected noise by an antenna at Bell
Labs in New Jersey in 1964. That noise turned out to be the cosmic
microwave background, the afterglow of the big bang fireball. "Not
only did it earn Arno Penzias and Robert Wilson a Nobel prize, but it
confirmed the big bang and opened up a whole field of cosmology," says
Cramer.

Hogan is more specific. "Forget Quantum of Solace, we would have
directly observed the quantum of time," says Hogan. "It's the smallest
possible interval of time - the Planck length divided by the speed of
light."

More importantly, confirming the holographic principle would be a big
help to researchers trying to unite quantum mechanics and Einstein's
theory of gravity. Today the most popular approach to quantum gravity
is string theory, which researchers hope could describe happenings in
the universe at the most fundamental level. But it is not the only
show in town. "Holographic space-time is used in certain approaches to
quantising gravity that have a strong connection to string theory,"
says Cramer. "Consequently, some quantum gravity theories might be
falsified and others reinforced."

Hogan agrees that if the holographic principle is confirmed, it rules
out all approaches to quantum gravity that do not incorporate the
holographic principle. Conversely, it would be a boost for those that
do - including some derived from string theory and something called
matrix theory. "Ultimately, we may have our first indication of how
space-time emerges out of quantum theory." As serendipitous
discoveries go, it's hard to get more ground-breaking than that.

Marcus Chown is the author of Quantum Theory Cannot Hurt You (Faber, 2008)

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7a.

Re: Pelajar2 SMA

Posted by: "Zaenal Arief" zaenal@pudak.com

Fri Jan 16, 2009 8:49 am (PST)

ini key boardnya rusak?????

----- Original Message -----
From: mariany baru
To: Fisika_indonesia@yahoogroups.com
Sent: Thursday, January 15, 2009 8:20 PM
Subject: [FISIKA] Pelajar2 SMA

How are all of you?
Oy,apakh d&#39;groups milis nc ad x mci plJar SMA?
Lw ad tlg bls email dr sy yc.
Sy ingin slg kNal dgn sSma pelajar SMA agr dpt lbh byk brtUKar informasi.
Thanks...
Warm regards :
Marianý

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8a.

Re: Bls: Re : [FISIKA] ARUS AC PLN.

Posted by: "amanubillah" amanubillah@yahoo.com   amanubillah

Fri Jan 16, 2009 8:50 am (PST)

klo misalkan arus litrik ac itu arahnya bolak-balik,bgmn penjelasan
penyuplyan listrik dari pln ke rumah-rumah(krn arah arusnya
bolak-balik).apa dari rumah menyupply pln lagi.kan lucu itu,trimakasih

maaf klo saya masuh banyak yang blm tau

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9.

klo misalkan Indonesia bangun PLTN

Posted by: "amanubillah" amanubillah@yahoo.com   amanubillah

Fri Jan 16, 2009 8:50 am (PST)

klo misalkan Indonesia bangun PLTN,bmn cara mendapatkan bahan bakar
Nuklir,tlng beri penjelasan.

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