Theory: Universe is a Hologram

[TheGodlessUtopian]

Article: http://www.nature.com/news/simulations-back-up-theory-that-universe-is-a-hologram-1.14328

I didn't really understand it but it sounded interesting.

[Sinister Intents]

This is quite fascinating! Makes me wanna look more into physics :) I'm not quite sure what else to say....

[Don't Swallow The Cap]

Article: http://www.nature.com/news/simulations-back-up-theory-that-universe-is-a-hologram-1.14328

I didn't really understand it but it sounded interesting.


I was just about to post this article with the exact same commentary.:lol:

This all sounds so interesting if only understood the concepts and their possible implications. :glare:

[Skyhilist]

Article: http://www.nature.com/news/simulations-back-up-theory-that-universe-is-a-hologram-1.14328

I didn't really understand it but it sounded interesting.

I stopped understanding when I got to "a ten-dimensional theory of gravity".

[ÑóẊîöʼn]

On the other hand:

Why Our Universe Is Not a Hologram (http://www.universetoday.com/107172/why-our-universe-is-not-a-hologram/)


While Maldacena made a compelling argument, it was a conjecture, not a formal proof. So there has been a lot of theoretical work trying to find such a proof. Now, two papers have come out (here (http://arxiv.org/abs/1311.7526) and here (http://arxiv.org/abs/1311.5607)) demonstrating that the conjecture works for a particular theoretical case. Of course the situation they examined was for a hypothetical universe, not a universe like ours. So this new work is really a mathematical test that proves the AdS/CFT correspondence for a particular situation.

From this you get a headline implying that we live in a hologram. On twitter, Ethan Siegel (https://twitter.com/StartsWithABang) proposed a more sensible headline: “Important idea of string theory shown not to be mathematically inconsistent in one particular way”.

Of course that would probably get less attention.

I also think the linked article does a better job of attempting to explain the concept in layman's terms:


In 1993, Gerard t’Hooft proposed what is now known as the holographic principle (http://arxiv.org/abs/hep--th/0003004), which argued that the information contained within a region of space can be determined by the information at the surface that contains it. Mathematically, the space can be represented as a hologram of the surface that contains it.

That idea is not as wild as it sounds. For example, suppose there is a road 10 miles long, and its is “contained” by a start line and a finish line. Suppose the speed limit on this road is 60 mph, and I want to determine if a car has been speeding. One way I could do this is to watch a car the whole length of the road, measuring its speed the whole time. But another way is to simply measure when a car crosses the start line and finish line. At a speed of 60 mph, a car travels a mile a minute, so if the time between start and finish is less than 10 minutes, I know the car was speeding.

The holographic principle applies that idea to string theory. Just as its much easier to measure the start and finish times than constantly measure the speed of the car, it is much easier to do physics on the surface hologram than it is to do physics in the whole volume. The idea really took off when Juan Martín Maldacena derived what is known as the AdS/CFT correspondence (an arxiv version of his paper is here (http://arxiv.org/abs/hep-th/9711200)), which uses the holographic principle to connect the strings of particle physics string theory with the geometry of general relativity.

[bcbm]

I stopped understanding when I got to "a ten-dimensional theory of gravity".

hf2CxZPl7KI

[Paul Cockshott]

This must be related to the Bekenstein limit to the information content of a volume of space http://en.wikipedia.org/wiki/Bekenstein_bound

[Sasha]

Anyone watch the "science of Dr who" lecture that was (re)broadcasted last night? The Dr who angle was a popscience stick but the lecture was really good in explaining general relativity, black holes and "time travel"... Tryin to reproduce anything of it still makes my head hurt but it was the best layman's explanation I have seen in a long time.

[argeiphontes]

Dr who

Ah, Dr. Who. It's like Star Trek for nerds...
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Gotta love it.

[ÑóẊîöʼn]

One thing to keep in mind with stuff like this, is to not mistake the map for the territory (http://rationalwiki.org/wiki/Mistaking_the_map_for_the_territory).

In other words, just because the mathematics is consistent with reality (much like how a well-made map of the real world is consistent with what it represents), that doesn't mean that the mathematical model is true to life in every detail. Much like how hills in real life don't have contour lines (http://en.wikipedia.org/wiki/Contour_line) like maps do, the holographic model of universe is likely to be an abstraction of some kind.

[Slavic]

I think that the term holographic is misrepresenting of the models they are trying to use for the universe. The "surface" that we observe with its various phenomenon like gravity are not "holographic" just merely the sum total of lower dimension quantum physics. Just because we can hypothesis a lower dimension without gravity does not mean that the gravity that we observe is any less a true occurring phenomenon. It just means the basis of the gravity we experience is not Einstein-based but follows a different mathematical formula.