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	<title>Comments on: The Black Hole War</title>
	<atom:link href="http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/feed/" rel="self" type="application/rss+xml" />
	<link>http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/</link>
	<description>Random samplings from a universe of ideas.</description>
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		<title>By: Darrel Lancaster</title>
		<link>http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/comment-page-2/#comment-91966</link>
		<dc:creator>Darrel Lancaster</dc:creator>
		<pubDate>Tue, 25 Aug 2009 09:20:30 +0000</pubDate>
		<guid isPermaLink="false">http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/#comment-91966</guid>
		<description>Theoretical arguments are great, and allow for the completely improbable to become possible. The argument over how information could be bombarded at the event horizon, and the supposition that nothing can travel faster than the speed of light...what if it can, and that is why we see a black hole, as there is nothing being reflected.</description>
		<content:encoded><![CDATA[<p>Theoretical arguments are great, and allow for the completely improbable to become possible. The argument over how information could be bombarded at the event horizon, and the supposition that nothing can travel faster than the speed of light&#8230;what if it can, and that is why we see a black hole, as there is nothing being reflected.</p>
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	<item>
		<title>By: String Theory and the Multiverse - Christian Forums</title>
		<link>http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/comment-page-2/#comment-78901</link>
		<dc:creator>String Theory and the Multiverse - Christian Forums</dc:creator>
		<pubDate>Sat, 13 Jun 2009 22:31:45 +0000</pubDate>
		<guid isPermaLink="false">http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/#comment-78901</guid>
		<description>[...] of my favorite books is The Black Hole War.   The Black Hole War &#124; Cosmic Variance &#124; Discover Magazine     __________________ To view links or images in signatures your post count must be 10 or greater. [...]</description>
		<content:encoded><![CDATA[<p>[...] of my favorite books is The Black Hole War.   The Black Hole War | Cosmic Variance | Discover Magazine     __________________ To view links or images in signatures your post count must be 10 or greater. [...]</p>
]]></content:encoded>
	</item>
	<item>
		<title>By: Where Does the Entropy Go? &#124; Cosmic Variance &#124; Discover Magazine</title>
		<link>http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/comment-page-2/#comment-58847</link>
		<dc:creator>Where Does the Entropy Go? &#124; Cosmic Variance &#124; Discover Magazine</dc:creator>
		<pubDate>Mon, 12 Jan 2009 18:10:42 +0000</pubDate>
		<guid isPermaLink="false">http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/#comment-58847</guid>
		<description>[...] is &#8220;How does the information get out?&#8221; An increasing number of physicists believe that the evaporation of black holes conserves information, but they don&#8217;t know precisely how the details of the state which created the black hole get [...]</description>
		<content:encoded><![CDATA[<p>[...] is &#8220;How does the information get out?&#8221; An increasing number of physicists believe that the evaporation of black holes conserves information, but they don&#8217;t know precisely how the details of the state which created the black hole get [...]</p>
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	<item>
		<title>By: Lawrence B. Crowell</title>
		<link>http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/comment-page-2/#comment-45652</link>
		<dc:creator>Lawrence B. Crowell</dc:creator>
		<pubDate>Tue, 12 Aug 2008 03:00:18 +0000</pubDate>
		<guid isPermaLink="false">http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/#comment-45652</guid>
		<description>It gets a little deeper than this.  The fields on a three dimensional space, or space plus time in four dimensions are determined by fields which are on a slice within a two dimensional null congurence.  This relationship between fields in this manner involves some subtle matters of Lagrangians on a full space and the Chern-Simons Lagrangian on a subchain or cycle.  This can lead to ways of constructing a &quot;mass&quot; for black holes from gauge charges, similar to BPS black holes.  In this way it leads to a 3 + 2 dimensions which is dual to the CFT on S^5.

Lawrence B. Crowell</description>
		<content:encoded><![CDATA[<p>It gets a little deeper than this.  The fields on a three dimensional space, or space plus time in four dimensions are determined by fields which are on a slice within a two dimensional null congurence.  This relationship between fields in this manner involves some subtle matters of Lagrangians on a full space and the Chern-Simons Lagrangian on a subchain or cycle.  This can lead to ways of constructing a &#8220;mass&#8221; for black holes from gauge charges, similar to BPS black holes.  In this way it leads to a 3 + 2 dimensions which is dual to the CFT on S^5.</p>
<p>Lawrence B. Crowell</p>
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		<title>By: collin237</title>
		<link>http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/comment-page-1/#comment-45651</link>
		<dc:creator>collin237</dc:creator>
		<pubDate>Mon, 11 Aug 2008 19:58:42 +0000</pubDate>
		<guid isPermaLink="false">http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/#comment-45651</guid>
		<description>By &quot;3+2 dimensional&quot; do you mean that the two interpretations (internal and external) are interpolated by a parameter that behaves like an extra time-like dimension? (As if the internal and external observers are looking at the surfaces of bread surrounding a 5-dimensional sandwich?)</description>
		<content:encoded><![CDATA[<p>By &#8220;3+2 dimensional&#8221; do you mean that the two interpretations (internal and external) are interpolated by a parameter that behaves like an extra time-like dimension? (As if the internal and external observers are looking at the surfaces of bread surrounding a 5-dimensional sandwich?)</p>
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		<title>By: Lawrence B. Crowell</title>
		<link>http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/comment-page-1/#comment-45650</link>
		<dc:creator>Lawrence B. Crowell</dc:creator>
		<pubDate>Mon, 11 Aug 2008 17:59:02 +0000</pubDate>
		<guid isPermaLink="false">http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/#comment-45650</guid>
		<description>The black hole duality indicates that an exterior observer, at &quot;infinity,&quot; will see fields which have entered a black hole according to harmonic oscillator modes (or string vibrations) on a membrane a Planck unit length above the event horizon.  The Russian for a black hole is a frozen hole, where because of time dilation nothing is ever seen to cross the r = 2M.  Then as the black hole decays away these modes end up being radiated away in three space (or 4-dim spacetime).  Conversely for an observer which enters the black hole their quantum information is not seen pinned to the event horizon, but taken in by the singularity, or some type of quantum-mawl in the interior.

This is the matter of black hole complementarity, which is that the observers outside and inside a black hole observe the same field amplitudes, but in complementary forms.  Loosely put, the exterior viewpoint has fields on this membrane above the horizon, similar to a type of D2-brane, equivalent to fields in space removed from the black hole.  So there is a 3 + 2 dimensional perspective on fields as measured outside the black hole.  The interior is given by a D5-brane, and the duality says that the amplitudes on the two are equivalent.

Lawrence B. Crowell</description>
		<content:encoded><![CDATA[<p>The black hole duality indicates that an exterior observer, at &#8220;infinity,&#8221; will see fields which have entered a black hole according to harmonic oscillator modes (or string vibrations) on a membrane a Planck unit length above the event horizon.  The Russian for a black hole is a frozen hole, where because of time dilation nothing is ever seen to cross the r = 2M.  Then as the black hole decays away these modes end up being radiated away in three space (or 4-dim spacetime).  Conversely for an observer which enters the black hole their quantum information is not seen pinned to the event horizon, but taken in by the singularity, or some type of quantum-mawl in the interior.</p>
<p>This is the matter of black hole complementarity, which is that the observers outside and inside a black hole observe the same field amplitudes, but in complementary forms.  Loosely put, the exterior viewpoint has fields on this membrane above the horizon, similar to a type of D2-brane, equivalent to fields in space removed from the black hole.  So there is a 3 + 2 dimensional perspective on fields as measured outside the black hole.  The interior is given by a D5-brane, and the duality says that the amplitudes on the two are equivalent.</p>
<p>Lawrence B. Crowell</p>
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		<title>By: collin237</title>
		<link>http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/comment-page-1/#comment-45573</link>
		<dc:creator>collin237</dc:creator>
		<pubDate>Sun, 10 Aug 2008 19:53:43 +0000</pubDate>
		<guid isPermaLink="false">http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/#comment-45573</guid>
		<description>I mean how can an interior field be controlled from a surface it can&#039;t classically communicate with?

If the surface is the cosmological horizon, this is clearly not a moot point. Without a non-relativistic causality, it would mean everything we observe has already been decided billions of years ago.</description>
		<content:encoded><![CDATA[<p>I mean how can an interior field be controlled from a surface it can&#8217;t classically communicate with?</p>
<p>If the surface is the cosmological horizon, this is clearly not a moot point. Without a non-relativistic causality, it would mean everything we observe has already been decided billions of years ago.</p>
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		<title>By: Lawrence B. Crowell</title>
		<link>http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/comment-page-1/#comment-45649</link>
		<dc:creator>Lawrence B. Crowell</dc:creator>
		<pubDate>Sun, 10 Aug 2008 14:17:30 +0000</pubDate>
		<guid isPermaLink="false">http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/#comment-45649</guid>
		<description>It looks like I messed up the tex on that equation.  Ng&#039;s fluctuation equation for a volume of length scale L bounded by an area is

$latex
\Big(\frac{\delta L}{L}\Big)^3~ge~\Big(\frac{L_p}{L}\Big)^2
$

L. C.</description>
		<content:encoded><![CDATA[<p>It looks like I messed up the tex on that equation.  Ng&#8217;s fluctuation equation for a volume of length scale L bounded by an area is</p>
<p>$latex<br />
\Big(\frac{\delta L}{L}\Big)^3~ge~\Big(\frac{L_p}{L}\Big)^2<br />
$</p>
<p>L. C.</p>
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		<title>By: Lawrence B. Crowell</title>
		<link>http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/comment-page-1/#comment-45648</link>
		<dc:creator>Lawrence B. Crowell</dc:creator>
		<pubDate>Sun, 10 Aug 2008 12:48:15 +0000</pubDate>
		<guid isPermaLink="false">http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/#comment-45648</guid>
		<description>I am not sure what is meant by inner or outer causality.

If the holographic theory is correct then metric fluctuations of spacetime should manifest themselves on a scale larger than the Planck length.  Y. Jack Ng has shown that the fluctuations in a three dimensional volume are equated to those on a two dimensional bounding region by

$latex
\(Big(delta L}{L}\Big)^3~\ge~\Big(\frac{L_p}{L}\Big)^2, L_p~=~\sqrt{G\hbar/c^3}
$

and so by solving for the delta L fluctuation these occur on a scale considerably larger than the tiny Planck length L_p.

The AdS/CFT is largely a stringy result.  However, aspects of string theory shows up in a number of forms --- such as sphere packing and quantum codes.  It also sneeks its way into Jordan exceptional algebras in loop quantum variables.  So physics probably has both stringy and loopy aspects to it.

Lawrence B. Crowell</description>
		<content:encoded><![CDATA[<p>I am not sure what is meant by inner or outer causality.</p>
<p>If the holographic theory is correct then metric fluctuations of spacetime should manifest themselves on a scale larger than the Planck length.  Y. Jack Ng has shown that the fluctuations in a three dimensional volume are equated to those on a two dimensional bounding region by</p>
<p>$latex<br />
\(Big(delta L}{L}\Big)^3~\ge~\Big(\frac{L_p}{L}\Big)^2, L_p~=~\sqrt{G\hbar/c^3}<br />
$</p>
<p>and so by solving for the delta L fluctuation these occur on a scale considerably larger than the tiny Planck length L_p.</p>
<p>The AdS/CFT is largely a stringy result.  However, aspects of string theory shows up in a number of forms &#8212; such as sphere packing and quantum codes.  It also sneeks its way into Jordan exceptional algebras in loop quantum variables.  So physics probably has both stringy and loopy aspects to it.</p>
<p>Lawrence B. Crowell</p>
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		<title>By: collin237</title>
		<link>http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/comment-page-1/#comment-45570</link>
		<dc:creator>collin237</dc:creator>
		<pubDate>Fri, 08 Aug 2008 23:44:27 +0000</pubDate>
		<guid isPermaLink="false">http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/#comment-45570</guid>
		<description>Isn&#039;t that just replacing the &quot;inner causal&quot; with an &quot;outer causal&quot;?

And what validity does it have for a non-stringist like me?</description>
		<content:encoded><![CDATA[<p>Isn&#8217;t that just replacing the &#8220;inner causal&#8221; with an &#8220;outer causal&#8221;?</p>
<p>And what validity does it have for a non-stringist like me?</p>
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		<title>By: Lawrence B. Crowell</title>
		<link>http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/comment-page-1/#comment-45572</link>
		<dc:creator>Lawrence B. Crowell</dc:creator>
		<pubDate>Fri, 08 Aug 2008 20:32:05 +0000</pubDate>
		<guid isPermaLink="false">http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/#comment-45572</guid>
		<description>The holographic principle has connections with the S^5 ~ AdS duality in superstring theory.  It on lower dimensions tells us that field amplitudes in three dimensional space at a given &quot;time&quot; are projections from fields pinned to event horizons.

Lawrence B. Crowell</description>
		<content:encoded><![CDATA[<p>The holographic principle has connections with the S^5 ~ AdS duality in superstring theory.  It on lower dimensions tells us that field amplitudes in three dimensional space at a given &#8220;time&#8221; are projections from fields pinned to event horizons.</p>
<p>Lawrence B. Crowell</p>
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		<title>By: mathematician</title>
		<link>http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/comment-page-1/#comment-45571</link>
		<dc:creator>mathematician</dc:creator>
		<pubDate>Fri, 08 Aug 2008 20:03:46 +0000</pubDate>
		<guid isPermaLink="false">http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/#comment-45571</guid>
		<description>I think the Holographic Principle is just a way for people to pretend they&#039;re developing a profoundly deep understanding, when really they&#039;re just superficially scratching the surface. ;)</description>
		<content:encoded><![CDATA[<p>I think the Holographic Principle is just a way for people to pretend they&#8217;re developing a profoundly deep understanding, when really they&#8217;re just superficially scratching the surface. <img src='http://blogs.discovermagazine.com/cosmicvariance/wp-includes/images/smilies/icon_wink.gif' alt=';)' class='wp-smiley' /> </p>
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		<title>By: collin237</title>
		<link>http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/comment-page-1/#comment-45610</link>
		<dc:creator>collin237</dc:creator>
		<pubDate>Fri, 08 Aug 2008 19:21:30 +0000</pubDate>
		<guid isPermaLink="false">http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/#comment-45610</guid>
		<description>Is the Holographic Principle a higher-dimensional version of Cauchy&#039;s Integral from complex calculus?</description>
		<content:encoded><![CDATA[<p>Is the Holographic Principle a higher-dimensional version of Cauchy&#8217;s Integral from complex calculus?</p>
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		<title>By: Lawrence B. Crowell</title>
		<link>http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/comment-page-1/#comment-45609</link>
		<dc:creator>Lawrence B. Crowell</dc:creator>
		<pubDate>Fri, 08 Aug 2008 14:24:32 +0000</pubDate>
		<guid isPermaLink="false">http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/#comment-45609</guid>
		<description>PS, by rotations with Pauli matrices I mean generators of the form

$latex
U(\theta) = exp(i\sigma_a\theta_a)
$

for the index around the axis to be rotated.

Susskind&#039;s black hole complementarity and holographic principle indicates that states which are identifiable on a membrane which wraps the black hole horizon are dual to states inside the black hole.  This does suggest some deep connections with quantum gravity, for it the black hole becomes very small the horizon might become &quot;blurred&quot; by quantum fluctuations and the fields associated with the horizon and those in the interior will exhibit new physics.

Lawrence B. Crowell</description>
		<content:encoded><![CDATA[<p>PS, by rotations with Pauli matrices I mean generators of the form</p>
<p>$latex<br />
U(\theta) = exp(i\sigma_a\theta_a)<br />
$</p>
<p>for the index around the axis to be rotated.</p>
<p>Susskind&#8217;s black hole complementarity and holographic principle indicates that states which are identifiable on a membrane which wraps the black hole horizon are dual to states inside the black hole.  This does suggest some deep connections with quantum gravity, for it the black hole becomes very small the horizon might become &#8220;blurred&#8221; by quantum fluctuations and the fields associated with the horizon and those in the interior will exhibit new physics.</p>
<p>Lawrence B. Crowell</p>
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		<title>By: Lawrence B. Crowell</title>
		<link>http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/comment-page-1/#comment-45608</link>
		<dc:creator>Lawrence B. Crowell</dc:creator>
		<pubDate>Fri, 08 Aug 2008 14:19:38 +0000</pubDate>
		<guid isPermaLink="false">http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/#comment-45608</guid>
		<description>To transmit information about the state you are teleporting you must communicate on the classical channel information about the the entanglement of the shared Bell state and the state to be transmitted.  You then communicate the outcomes.  The rotations performed by the recipient will rotate their state into a form which recovers the teleported state.  This can be shown with rotations by Pauli matrices.  It is not excessively difficult to do, but does require a page or two of calculation.

Lawrence B. Crowell</description>
		<content:encoded><![CDATA[<p>To transmit information about the state you are teleporting you must communicate on the classical channel information about the the entanglement of the shared Bell state and the state to be transmitted.  You then communicate the outcomes.  The rotations performed by the recipient will rotate their state into a form which recovers the teleported state.  This can be shown with rotations by Pauli matrices.  It is not excessively difficult to do, but does require a page or two of calculation.</p>
<p>Lawrence B. Crowell</p>
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		<title>By: collin237</title>
		<link>http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/comment-page-1/#comment-45607</link>
		<dc:creator>collin237</dc:creator>
		<pubDate>Fri, 08 Aug 2008 12:58:33 +0000</pubDate>
		<guid isPermaLink="false">http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/#comment-45607</guid>
		<description>It occurred to me that Sean&#039;s &quot;horror&quot; at the title of Susskind&#039;s book may not be that far off the mark. Not only does a black hole have a horizon that hides things from observers; it also has a force that &lt;em&gt;destroys&lt;/em&gt; any observers that get too close to it. So the universe &lt;em&gt;is&lt;/em&gt; made &quot;safe&quot; for the laws of physics, because the violations a black hole commits cannot be known about.

Any attempt to deduce the structure of a black hole from the laws of physics is a total waste of time.</description>
		<content:encoded><![CDATA[<p>It occurred to me that Sean&#8217;s &#8220;horror&#8221; at the title of Susskind&#8217;s book may not be that far off the mark. Not only does a black hole have a horizon that hides things from observers; it also has a force that <em>destroys</em> any observers that get too close to it. So the universe <em>is</em> made &#8220;safe&#8221; for the laws of physics, because the violations a black hole commits cannot be known about.</p>
<p>Any attempt to deduce the structure of a black hole from the laws of physics is a total waste of time.</p>
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		<title>By: collin237</title>
		<link>http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/comment-page-1/#comment-45606</link>
		<dc:creator>collin237</dc:creator>
		<pubDate>Fri, 08 Aug 2008 04:17:40 +0000</pubDate>
		<guid isPermaLink="false">http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/#comment-45606</guid>
		<description>&lt;blockquote&gt;I then make a measurement of the state I want to teleport and find one of the four outcomes&lt;/blockquote&gt;

1. Why would you find mixtures like that?
2. I assume &quot;rotation&quot; refers to an SU2xSU2 group. Is that correct?
3. Are the x, y, and z axes only an isospin basis, or do they have actual directions in a physical frame?
4. What is a zero rotation?</description>
		<content:encoded><![CDATA[<blockquote><p>I then make a measurement of the state I want to teleport and find one of the four outcomes</p></blockquote>
<p>1. Why would you find mixtures like that?<br />
2. I assume &#8220;rotation&#8221; refers to an SU2xSU2 group. Is that correct?<br />
3. Are the x, y, and z axes only an isospin basis, or do they have actual directions in a physical frame?<br />
4. What is a zero rotation?</p>
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		<title>By: Lawrence B. Crowell</title>
		<link>http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/comment-page-1/#comment-45647</link>
		<dc:creator>Lawrence B. Crowell</dc:creator>
		<pubDate>Thu, 07 Aug 2008 22:30:23 +0000</pubDate>
		<guid isPermaLink="false">http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/#comment-45647</guid>
		<description>We do have a bit of the classical/quantum split.  Classical information are bits which are not defined according to quantum states, nor do they have any fundamental unit of action (hbar).  One of the big questions underlying this is &quot;why the classical world?&quot;  We all have a sense that the classical trajectory or orbit of even the biggest object is built up from quantum paths.

Lawrence B. Crowell</description>
		<content:encoded><![CDATA[<p>We do have a bit of the classical/quantum split.  Classical information are bits which are not defined according to quantum states, nor do they have any fundamental unit of action (hbar).  One of the big questions underlying this is &#8220;why the classical world?&#8221;  We all have a sense that the classical trajectory or orbit of even the biggest object is built up from quantum paths.</p>
<p>Lawrence B. Crowell</p>
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		<title>By: mathematician</title>
		<link>http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/comment-page-1/#comment-45646</link>
		<dc:creator>mathematician</dc:creator>
		<pubDate>Thu, 07 Aug 2008 21:38:22 +0000</pubDate>
		<guid isPermaLink="false">http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/#comment-45646</guid>
		<description>What is the definition of &quot;classical information&quot; in a quantum universe?</description>
		<content:encoded><![CDATA[<p>What is the definition of &#8220;classical information&#8221; in a quantum universe?</p>
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	<item>
		<title>By: Lawrence B. Crowell</title>
		<link>http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/comment-page-1/#comment-45645</link>
		<dc:creator>Lawrence B. Crowell</dc:creator>
		<pubDate>Thu, 07 Aug 2008 21:27:12 +0000</pubDate>
		<guid isPermaLink="false">http://blogs.discovermagazine.com/cosmicvariance/2008/07/28/the-black-hole-war/#comment-45645</guid>
		<description>If I understand you (Collin237) right you appear to be confusing the classical information with some sort of &quot;inner causal&quot; connection.

Suppose that you and I have a quantum state which are in an entangeled state.  Say these states are due to the decay of a spin-0 boson, and which decay into two fermions.  You and I are separated by some considerable distance.  So we both then have this Bell state.  Now suppose that I have another state &#124;Y&gt; = a&#124;+) + b&#124;-) that I want to teleport to you.  So I then entangle this state with the Bell state so I have &#124;Y)&#124;B).  By such an entanglement since you hold part of the EPR pair your state is similarly entangled.  I then make a measurement of the state I want to teleport and find one of the four outcomes

&#124;+)&#124;-) - &#124;-)&#124;+)

&#124;+)&#124;-) + &#124;-)&#124;+)

&#124;+)&#124;+) - &#124;-)&#124;-)

&#124;+)&#124;+) + &#124;-)&#124;-)

What I do is then communicate each of these possible outcomes with the numbers 1, 2, 3, 4 as classical information.  If you then take your Bell state and perform the following operations:

1: 0 rotation

2: pi rotation about the z axis

3: pi rotation about x axis

4: pi rotation about y axis

you will reconstruct the state I am intending to transmit because of its entanglement with your part of the EPR pair.

The point of going through all of this is that without the classical information you will not beable to reconstruct the state properly.  Further, the total information communicated involves 2 bits, but from that the state you find exists in the whole H^4 state space or points on the Bloch sphere.

Lawrence B. Crowell</description>
		<content:encoded><![CDATA[<p>If I understand you (Collin237) right you appear to be confusing the classical information with some sort of &#8220;inner causal&#8221; connection.</p>
<p>Suppose that you and I have a quantum state which are in an entangeled state.  Say these states are due to the decay of a spin-0 boson, and which decay into two fermions.  You and I are separated by some considerable distance.  So we both then have this Bell state.  Now suppose that I have another state |Y&gt; = a|+) + b|-) that I want to teleport to you.  So I then entangle this state with the Bell state so I have |Y)|B).  By such an entanglement since you hold part of the EPR pair your state is similarly entangled.  I then make a measurement of the state I want to teleport and find one of the four outcomes</p>
<p>|+)|-) &#8211; |-)|+)</p>
<p>|+)|-) + |-)|+)</p>
<p>|+)|+) &#8211; |-)|-)</p>
<p>|+)|+) + |-)|-)</p>
<p>What I do is then communicate each of these possible outcomes with the numbers 1, 2, 3, 4 as classical information.  If you then take your Bell state and perform the following operations:</p>
<p>1: 0 rotation</p>
<p>2: pi rotation about the z axis</p>
<p>3: pi rotation about x axis</p>
<p>4: pi rotation about y axis</p>
<p>you will reconstruct the state I am intending to transmit because of its entanglement with your part of the EPR pair.</p>
<p>The point of going through all of this is that without the classical information you will not beable to reconstruct the state properly.  Further, the total information communicated involves 2 bits, but from that the state you find exists in the whole H^4 state space or points on the Bloch sphere.</p>
<p>Lawrence B. Crowell</p>
]]></content:encoded>
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