Archive for the ‘astrophysics’ Category

Classical physics implies that anything falling through the horizon of a black hole can never escape. But Hawking showed that black holes continually emit radiation once quantum effects are taken into account. Unfortunately, for typical astrophysical black holes, the temperature of this radiation is far lower than that of the cosmic microwave background and we have no way of proving it. If a black hole continually emits radiation, it will continually lose mass – eventually evaporating. Hawking realized that this implied a paradox: if a black hole can evaporate, the information about it will be lost forever. This means that even if we could measure the radiation from a black hole we could never figure out it was originally formed. This violates an important rule of quantum mechanics that states information cannot be lost or created.

Determinism implies that the state of the universe at any given time is uniquely determined from its state at any other time. This is how we can trace its evolution both astronomically and mathematically though quantum mechanics.

If a black hole can evaporate and information lost how will determinism work? Black hole physics provides a test for any potential quantum gravity theory. Whatever your theory is, it must explain what happens to the information recording a black hole’s history.

It took two decades for scientists and they have come up with an answer. They suggested that the information stored in a black hole is proportional to its surface area (in two dimensions) rather than its volume (in three dimensions). This could be explained by quantum gravity, where the three dimensions of space could be reconstructed from a two-dimensional world without gravity – much like a hologram. See a problem like quantum gravity can disappear if we make the universe is a hologram: the real action would play out where gravity is zero. In regimes where there are no analytic tests a holographic universe replaces actual proof.

In this context we have Maldacena conjecture and it  reconciles Einstein’s General Theory of Relativity and quantum mechanics.

Shortly afterwards, string theory, the most studied theory of quantum gravity was also shown to be holographic.

Using holography we can describe the evaporation of the black hole in the two-dimensional world without gravity, for which the usual rules of quantum mechanics apply. This process is deterministic, with small imperfections in the radiation encoding the history of the black hole. So holography tells us that information is not lost in black holes, but tracking down the flaw in Hawking’s original arguments has been surprisingly hard.

Which came first? chicken or egg? Maldacena conjecture in this case makes chicken the hologram projection of egg where gravity is zero. Conversely shall we say chicken is the hologram projection of an egg in another time zone?

In a 4-D world of chickens , the eggs are entangled only in a flattened 3-D scaled down version of reality. Both are present.( cf.universe as a hologram)

(Ack: The Conversation June 24, 2015 -Don’t fear falling into a black hole – you may live on as a hologram- Prof.Marika Taylor/ in theoretical physics at Uni. of Southampton)


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