<story><title>Experiments Show Gravity Is Not an Emergent Phenomenon</title><url>http://www.technologyreview.com/blog/arxiv/27102/?ref=rss</url></story><parent_chain><item><author>powertower</author><text>How does this prove that gravity is not an emergant phenomena?&lt;p&gt;Doesn&apos;t this only claim that gravity and entropy don&apos;t have some type of a first order (direct) relationship?&lt;p&gt;Rant:&lt;p&gt;I never understood how you can explain gravity as 1) a bending of space-time caused by mass and then 2) pretend it&apos;s a force transmited by &quot;gravitons&quot;.&lt;p&gt;If 1) is true then it&apos;s an effect (phenomena), not a cause (force). If 2) is true than it&apos;s a cause (force), not an effect (phenomena).</text></item></parent_chain><comment><author>vinutheraj</author><text>Feynman has expressed his opinion on this in one of the Messenger lectures on the Character of Physical Law that he gave at Cornell.&lt;p&gt;&lt;i&gt;This is an example of the wide range of beautiful ways of
describing nature. When people say that nature must have
causality, you can use Newton&apos;s law; or if they say that
nature must be stated in terms of a minimum principle,
you talk about it this last way; or if they insist that nature must have a local field - sure, you can do that. The question is: which one is right? If these various alternatives are not exactly equivalent mathematically, if for certain ones there will be different consequences than for others, then all we
have to do is to experiment to find out which way nature
actually chooses to do it. People may come along and argue
philosophically that they like one better than another; but
we have learned from such experience that all philosophical
intuitions about what nature is going to do fail. One just
has to work out all the possibilities, and try all the alternatives. But in the particular case I am talking about the
theories are exactly equivalent. Mathematically each of the
three different formulations, Newton&apos;s law, the local field
method and the minimum principle, gives exactly the same
consequences. What do we do then? You will read in all
the books that we cannot decide scientifically on one or the
other. That is true. They are equivalent scientifically. It is impossible to make a decision, because there is no experimental way to distinguish between them if all the consequences are the same. But psychologically they are very
different in two ways. First, philosophically you like them
or do not like them; and training is the only way to beat
that disease. Second, psychologically they are different
because they are completely unequivalent when you are
trying to guess new laws.&lt;/i&gt;</text></comment>
<story><title>Experiments Show Gravity Is Not an Emergent Phenomenon</title><url>http://www.technologyreview.com/blog/arxiv/27102/?ref=rss</url></story><parent_chain><item><author>powertower</author><text>How does this prove that gravity is not an emergant phenomena?&lt;p&gt;Doesn&apos;t this only claim that gravity and entropy don&apos;t have some type of a first order (direct) relationship?&lt;p&gt;Rant:&lt;p&gt;I never understood how you can explain gravity as 1) a bending of space-time caused by mass and then 2) pretend it&apos;s a force transmited by &quot;gravitons&quot;.&lt;p&gt;If 1) is true then it&apos;s an effect (phenomena), not a cause (force). If 2) is true than it&apos;s a cause (force), not an effect (phenomena).</text></item></parent_chain><comment><author>mattheww</author><text>No, this paper claims that introducing gravity as an emergent phenomenon in Verlinde&apos;s framework breaks quantum mechanics. He shows that Verlinde&apos;s proposal changes the Hamiltonian. However, the solutions to the standard Schrodinger equation have been measured in experiments with ultra-cold neutrons and shown to agree (ergo, disagreeing with Verlinde&apos;s theory).&lt;p&gt;Regarding your &quot;rant&quot;: either way, it&apos;s still a force. Gravity still causes things to move. How that force is explained is clearly different in different theories. General Relativity suggests (1). Quantum Gravity theories suggest (2). Newton didn&apos;t really explain how it was mediated.&lt;p&gt;You could apply the same rant to QED: Either electrodynamics is caused by the bending of a vector potential by electric charge or it&apos;s a force transmitted by photons. The two statements are equivalent. But with gravity, we&apos;re not sure if quantum part is true.</text></comment>