New Scientist reports on an experiment to test whether the universe is a hologram.
From the article:
The experiment is testing the idea that the universe is actually made up of tiny "bits", in a similar way to how a newspaper photo is actually made up of dots. These fundamental units of space and time would be unbelievably tiny: a hundred billion billion times smaller than a proton. And like the well-known quantum behaviour of matter and energy, these bits of space-time would behave more like waves than particles.
The Femilab Holometer is designed to characterize the nature of spacetime itself, and if successful would mean that our basic assumptions about space and time are wrong. The device has just begun to record data and is expected to have gathered enough information to settle the question within a year.
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According to new research published by the American Physical Society in the Journal Physical Review letters, in the coming years it may be possible to test whether the universe is in fact a hologram.
The debate over The Holographic Principle — whether the universe is a flat (two dimensional) projection — is mind bending and still largely theoretical in nature. The holographic principle solves various problems, it can be used to explain quantum gravity and also
has been used to explain cosmic inflation, a pivotal period of time in the early universe where our cosmos expanded at quizzically breakneck speeds.
But an untestable theory, no matter how appealing the math, is ever an itch that needs scratching in science. So how do we do that?
During cosmic inflation, the universe became populated with quantum fluctuations, particles that temporarily appear out of empty space. “The inflationary universe had the right characteristics to make these fluctuations the seed of everything we observe today from the Cosmic Microwave Background, galaxies, stars, planets to cosmologists.”, said the researchers. These quantum fluctuations are what causes the irregular distribution of galaxies in the universe.
Through interactions with scalar fields, these fluctuations create distinct signals that can oscillate. To tell whether the universe is holographic, researchers took a look at the different intricate ways these signals could oscillate. If the signals are underdamped, meaning they move back and forth before reaching a point of equilibrium, then we can’t be living in a hologram. This is because if we’re living in a holographic universe, every signal we see must have a counterpart in a lower dimensional world. An underdamped signal can’t have such a counterpart.
In short, if we detect underdamped signals, we are not living in a holographic universe. And we can look for them:
(Score: 2, Interesting) by GoonDu on Monday September 01 2014, @03:37AM
>If space-time is smooth and shows no quantum behaviour, then the mirrors should remain perfectly still. But if both lasers measure an identical, small difference in the mirrors' position over time, that could mean the mirrors are being jiggled about by fluctuations in the fabric of space itself.
I might have remembered wrong but I thought due to the uncertainty principle, they will most probably find some fluctuation, right? Wouldn't a perfectly still mirror suggest that we know its speed AND position at the same time? Or is it because it's mirrors we are talking about and not particles, thus it's plausible to do this?
Personally, I find this fascinating so I look forward to their result next year.
(Score: 3, Informative) by c0lo on Monday September 01 2014, @08:00AM
Now, my "playing by the ear" interpretation:
Given they are using light, I think whatever the interpretation they will give to their findings is as good as "the speed of light is constant and does not fluctuate" ('cause, when you are using light as the only way of measurement, a "spacetime fluctuation" is indistinguishable from "space and time stayed actually the same, but the ε0·μ0 of the local vacuum just fluctuated causing a sloshing in the light beams they are using".
Anyway, the spacetime as a concept is actually defined based on the "speed of light is constant" as an axiom)
(the funny thing would be actually the space and time to fluctuate, speed of light to fluctuate as well but in such a manner their fluctuation to cancel as observables withing the experimental conditions. A situation like "God plays dice and the dice is so well loaded you'll never be able to observe anything wrong")
https://www.youtube.com/watch?v=aoFiw2jMy-0
(Score: 2) by hellcat on Monday September 01 2014, @09:31AM
Is this a fancier version of the Michaelson-Morley experiment?
(Score: 2) by c0lo on Monday September 01 2014, @07:01PM
https://www.youtube.com/watch?v=aoFiw2jMy-0
(Score: 0) by Anonymous Coward on Monday September 01 2014, @07:14PM
Not really, as MM was explicitly set up to detect the signal of a presumed almost constant velocity - us travelling through some medium; call it ether in one incarnation of the experiment, call it space-time in a more recent version. However this looks more like it's trying to analyse the noise that would accompany that signal. So related, but different.
I'm a little rusty, but I do share the reservations that other posters have expressed. The cynic in me expects silence in a year.
(Score: 2) by VLM on Monday September 01 2014, @01:57PM
This is a simplification but its something along the lines of if you make a whole bunch of graphs with "noise power" along the y-axis and frequency along the x-axis then "stuff" looks different. Thermal noise, seismic noise, your uncertainty principle as discussed... and if you model and subtract out all the known stuff you'll be left with a noise signal that none the less indicates a holographic universe. Holography in the physics sense not the hollywood sci fi action flick sense. Something to with peculiar resolution / noise / scintillation-ish stuff at very small scales. If the universe is not a 3/4 D hologram of something with more dimensions (a simplification) then they will likely see nothing unusual at all, or it'll prove the holographic effects are smaller than 0.000whatever which will give the theoreticians a big headache to explain or make them give up perhaps.
The data analysis is much like how the cosmic microwave background was found. Well, take this graph, and subtract out the known noise of the preamp, and subtract out the known noise of the ... and ten steps later you are stuck with 2.7 degrees kelvin (or whatever it is exactly) coming from everywhere in the sky. That implies blah blah blah...
If you insist on a shitty SN car analogy, if you knew nothing about cars but really carefully analyzed lots of 2-d pix of cars you'd eventually come up with a theoretical mathematical model where despite the world as you know it consisting of lots of 2-D pix, the math model does match experimental results (the pixs) where the 2-D pix are a snapshot of a 3-D universe. One obvious math model would be despite nearly never seeing all four tires at the same time in the same pix, none the less it "works out" that pretty much all 3-D models of cars all have exactly four wheels, despite how 2-D snapshots might look. In fact if a car was rotating on a turntable and you snapped video as it was turning, you could create a complete 3-D model of the car using nothing but lots of 2-D pixs and a megaton of data analysis math. This is a bit more ambitious than the holographic test guys are hoping for, but its the same general idea that lots of location data about our 3-d would might exhibit certain anomalies implying we're in a snapshot of a 12-d world. Or maybe 11-d. Or 44-D. I'm getting distracted now...
(Score: 2, Interesting) by sea on Monday September 01 2014, @07:28AM
Since they're searching for tiny movements caused by warping of space, they might just end up detecting gravity waves.
(Score: 2) by tynin on Monday September 01 2014, @10:51AM
LIGO is much larger detector specifically for gravity waves and they haven't yet detected any. Still you could be right, but i'd be surprised to see that result.
(Score: 2) by opinionated_science on Monday September 01 2014, @05:34PM
you should see the on in Livingston, LA. High-tech in a swamp....!
(Score: 0) by Anonymous Coward on Monday September 01 2014, @08:39AM
From the description, it sounds like they are "just" testing that the spacetime is actually quantum. But the spacetime being quantum does in no way imply that it is holographic.
Of course, if they indeed find that the spacetime is quantum, that would be a huge thing in itself, because it would be the first finding outside the established theories. Of course if they find that spacetime is not quantum, that would be an even more spectacular result, because basically everyone expects spacetime to be quantum.
In other words, that experiment, if it really can test quantumness of spacetime, will certainly be an important one. I just strongly doubt that it is a test specifically for a holographic universe.
(Score: 3, Insightful) by marcello_dl on Monday September 01 2014, @08:45AM
The discrete vs. continuous nature of the universe is just a feature. In fact the universe being continuous is just convenient arbitrary modeling at macroscopic scale and, while not strictly impossible, flies in the face of objections done since the Greeks had too much time on their hands and started philosophy.
The hologram nature is also a way of modeling the universe, how it works in practice can't be determined from the inside, just as you can't tell whether an mp3 player with 2 songs is in random or linear playing mode just by listening to the songs, because it will go song a -> song b -> song a either way.
So, science people, please be scientific and substitute "the universe being a hologram" with "the universe behaving as a hologram", the research and its value is unchanged if you do.
(Score: 0) by Anonymous Coward on Monday September 01 2014, @09:07AM
That depends on the implementation of the random mode. If, after all songs of the queue have been played once, the full queue is reshuffled, then the order may well be song a->song b->song b->song a->song b->song a->song a->song b ...
(Score: 0) by Anonymous Coward on Monday September 01 2014, @09:58AM
That would be a particularly stupid implementation, I don' t recall having heard a repeat the same song twice ever.
(Score: 2) by Magic Oddball on Monday September 01 2014, @09:10AM
you can't tell whether an mp3 player with 2 songs is in random or linear playing mode just by listening to the songs, because it will go song a -> song b -> song a either way
I'd think that being on random would mean that with only 2 possible choices, a decent percentage of the time it would play the same song two or more times in a row, rather than consistently alternating between the two -- wouldn't it?
(Score: 2) by marcello_dl on Monday September 01 2014, @10:02AM
My no brand mp3 player picks randomly one of the songs discarding the one currently played for obvious reasons.
Do your ones repeat the same song?
(Score: 1) by EETech1 on Monday September 01 2014, @03:11PM
With Rockbox, it will shuffle your entire library by creating a randomly ordered playlist. When the playlist is done, it creates a new playlist in a different order. This can cause the same song to get played as the last song of the old list, and the first song of a new list.
You can even see your progress through the list (song 415 / 900) as you play songs. Once you go past the last song (900 / 900 changes to 1 / 900), you can no longer navigate the old order the songs were played in, only the new shuffle order.
I've had it play a song twice in a row (especially when shuffling by album or by artist) and when I look to see if I have the song on there twice, if I see that it is at 1 / 9 or whatever, it is just the luck of the draw and i pick a new album. If I see it is 5 / 9 THEN I can hit back 4 / 9 will be the same song, and i delete the dupe.
So I'm sure my Iriver H10 with Rockbox will play the same song twice on shuffle. If you have repeat and shuffle enabled, it does not even track all of the songs to be sure they are all played once before playing them again, so it could play the same song 3 times in a row (or more) depending on the roll of the dice.
Cheers
(Score: 2) by WizardFusion on Monday September 01 2014, @03:06PM
So nothing to do with this then.? The Thirteenth Floor [imdb.com]
(Score: 2) by jasassin on Monday September 01 2014, @10:16PM
Intensely scientific articles should included an "explain it to me like I'm five" synopsis.
jasassin@gmail.com GPG Key ID: 0x663EB663D1E7F223