Join 3,424 readers in helping fund MetaFilter (Hide)


What are the dimensions of the universe?
July 11, 2008 10:09 AM   Subscribe

What are the dimensions of the universe?

First of all, I'm assuming there's about twelve from what I've been able to find so far. I don't yet have an understanding of m-theory, string theory, or superstring theory, which is where I'm assuming this pondering will lead eventually. In a nutshell, here's what I've got so far in thinking about this myself:

1. SPACE X left/right
2. SPACE Y up/down
3. SPACE Z in/out
4. TIME X diachronic (start to finish)
5. TIME Y synchronic (all possibility)
6. TIME Z (???)
7. COLOR X brightness (light to dark)
8. COLOR Y hue (the rainbow)
9. COLOR Z saturation (gray)

How does sound fit in? What about light (or should my description of "color" be considered "light" instead)?

Additionally, I'm assuming some sort of vortex ring model with a singularity as it seems the natural pattern formed by and infinite X & Y axis (plus seems to make sense in space w/ black holes, big bangs, etc).

I'm also a little confused about the z-axis in general with this vortex ring model, so if anyone has even the remotest idea of what I'm talking about, please chime in.
posted by BirdD0g to Science & Nature (47 answers total) 10 users marked this as a favorite
 
You can define them for yourself, which you seem to be doing, so you're fine.
posted by dhoe at 10:18 AM on July 11, 2008


Aren't the color dimensions you've listed simply derived from the behavior of light within the temporal and spatial dimensions?
posted by dreadpiratesully at 10:20 AM on July 11, 2008


This video is an interesting way of looking at it... Though IANAP (physicist) so I can't vouch for how correct this is.
posted by lukeo05 at 10:24 AM on July 11, 2008


The dimensions in m-theory or superstring theory are the four familiar spatiotemporal dimensions plus additional dimensions that do not correspond to any familiar or intuitive physical experiences. These dimensions are mathematical constructs with that are not observationally accessible outside the predictions of the theory.

This video is an interesting way of looking at it... Though IANAP (physicist) so I can't vouch for how correct this is.

It's basically nonsense. It's based on Madeleine L'Engle's A Wrinkle in Time, not physics.
posted by mr_roboto at 10:29 AM on July 11, 2008 [1 favorite]


When physicists say 12 (or so) dimensions, they really mean 12 spatial dimensions. It's not a metaphor, it's not any of these attributes that you're naming. They really do mean spatial dimensions.
posted by kiltedtaco at 10:29 AM on July 11, 2008 [5 favorites]


It's really not certain if humans will ever discern this.
posted by Burhanistan at 10:30 AM on July 11, 2008


≈8734;

About as good as an answer as you'll get, I think, even if mathematically incorrect.
posted by fogster at 10:33 AM on July 11, 2008


...that was an 8734;, or infinity symbol... Now it just says "Approximately equal to 8,734" and I look like a lunatic.
posted by fogster at 10:33 AM on July 11, 2008 [8 favorites]


If HSV color values really count as dimensions, we're all wasting our time on MeFi and should probably move to TimeCube.

Consider also that you're try to use X Y and Z "axes", which are spacial terms, for non-spacial... things. You're looking for some kind of aesthetically-pleasing symmetry that doesn't really make sense here.

Why is hue your Y-axis for color? Shouldn't it clearly be Z?
posted by rokusan at 10:35 AM on July 11, 2008 [2 favorites]


You might be interested in learning about linear algebra. It's the mathematical discipline that addresses issues of dimensionality, orthoganality, etc.

[infinity symbol] About as good as an answer as you'll get, I think, even if mathematically incorrect

Certainly you can list an arbitrary number of degrees of freedom for any system. The question is whether these form an orthogonal basis, which is a mathematically precise criterion. I'm not sure why you would consider a mathematically incorrect answer to be better than a mathematically correct answer. Scientific models of nature have been based on mathematics for the past 350 years, and have generally shown quite good predictive power.

If HSV color values really count as dimensions, we're all wasting our time on MeFi and should probably move to TimeCube.

Well, it all depends what you're using it for. Of course, in physical theories about the nature of the universe, assigning color dimensions is nonsensical. If you're building a color printer though, it's very useful.
posted by mr_roboto at 10:41 AM on July 11, 2008


I always thought that space was uniform and possibly infinite (or functionally so.)

I don't see how any sort of dimensional model beyond an arbitrarily defined nearby area could be useful.

How does sound fit in?

Er. Are you sure you aren't incredibly confused about all of this? Sound is a particulate disturbance.
posted by wfrgms at 10:42 AM on July 11, 2008


The Universe ranges in length, width, depth and time from 0 universes to 1 universe.
posted by Aquaman at 10:42 AM on July 11, 2008


(Alternate universes may vary.)
posted by Aquaman at 10:43 AM on July 11, 2008 [2 favorites]


From Wikipedia, which is as good a reference as any other, considering that what we "know" about our universe is pretty much all recent guesses that are being refined constantly by what we learn from cosmological theory, test, and observation not possible mere decades ago (whew...!):

The universe is very large and possibly infinite in volume; the observable matter is spread over a space at least 93 billion light years across.[11] F

So, from that,

1. SPACE X = 93e9 ly
2. SPACE Y = 93e9 ly
3. SPACE Z = 93e9 ly
4. TIME X diachronic (not a dimension)
5. TIME Y synchronic = 93e9 years
6. TIME Z (not a dimension)
7. COLOR X brightness (not a dimension)
8. COLOR Y hue (not a dimension - light wavelengths run from nearly infinitesimal to (potentially) 186 ly)
9. COLOR Z saturation (not a dimension)
posted by IAmBroom at 10:44 AM on July 11, 2008


I don't see how any sort of dimensional model beyond an arbitrarily defined nearby area could be useful.>

NASA uses such a model (general relativity) to plot the trajectories of interplanetary probes. Cosmologists use the same model to map astronomical observations to theories of the development of the early universe.
posted by mr_roboto at 10:46 AM on July 11, 2008


NASA uses such a model (general relativity) to plot the trajectories of interplanetary probes.

Huh. I thought NASA used Newtonian physics to plot trajectories of space craft...
posted by wfrgms at 10:55 AM on July 11, 2008


Only four dimensions (three space, one time) are known for sure. Other spatial dimensions have been posited.

Color is not a dimension. If you mean something along the lines of degrees of freedom (roughly, how many numbers are required to describe something), then you should be aware that the three degrees of freedom we commonly use to express color (hue/saturation/brightness or red/green/blue) are purely a function of how we perceive light, and not inherent in the nature of light itself. There are frequencies of light outside of our visual perception, and even within the visual spectrum, two instances of a color that look identical to us may have very different spectra (a graph of intensity vs. frequency). You'd need an infinite number of degrees of freedom to perfectly represent the light at a single point and a single time. Still further, to fully describe the universe you'd need to represent the different spectra present at each point and at each time.

Think of it this way: a picture taken with a digital camera isn't just three numbers; it's three numbers for each pixel in the picture. And with a conventional digital camera, the "colors" would probably seem way off to an alien which had a different visual perception than ours.
posted by DevilsAdvocate at 10:55 AM on July 11, 2008


Why colour? We can easily reduce colour to far more simple constructs.
Why must there be three time dimensions? Typically, we think of space as three dimensions and time as a fourth.
What about mass/energy? Consider how we measure things. We have three basic units: metres, seconds, and kilograms. The three spatial dimensions are measured in metres, time is measured in seconds, mass is measured in kg (and mass is equivalent to energy).
Why assume there must be twelve?
posted by ssg at 10:57 AM on July 11, 2008


Consider also that you're try to use X Y and Z "axes", which are spacial terms, for non-spacial... things. You're looking for some kind of aesthetically-pleasing symmetry that doesn't really make sense here.

Maybe. But hue is definitely Y in that it runs perpendicular to BRIGHTNESS.

On preview: I don't understand much about anything related to this. I'm more so trying to understand a model that seems to help understand a lot of different things (time, space, light, sound). So what I've listed may not be dimensions per se, but things that fit into this natural vortex ring model - a model which is the natural creation of looping the X axis and rotating it into a ring along Y and Z.

Whatever. Just thought I'd ask. Believe it or not, none of this is even substance-induced. Though it may be T.S. Eliot induced.
posted by BirdD0g at 10:59 AM on July 11, 2008


I think you're confused about what you mean by 'dimension'. Most physics theories are designed to work in only the dimensions we can observe: three spatial dimensions and one temporal dimension. Some theories (like string theory) predict more (spatial) dimensions that are not a part of our everyday existence.
Proponents of these theories say that even though we can't detect these extra dimensions with our current equipment, they are there, compacted so they are only detectable for very very small things.

Other things can have orthogonal 'dimensions' too, like light has hue and intensity. However, they aren't part of spacetime.

I don't understand what you mean by 'vortex ring model'.
posted by demiurge at 11:04 AM on July 11, 2008


I'm not sure I fully understand what your post is asking. There seem to be two questions here...

What are the dimensions of the universe?

If you mean the dimensions as in size it's not something we know a lot about. There are a multitude of theories, none particularly better supported than the others.

But then you list a bunch of things that are incomparable. So I think you've read something that lead you to understand that there are many "dimensions" by which things can be measured. So you listed some possibilites for us... but they're founded on significant misunderstanding.

No experiments have yet demonstrated any spatial dimensions other than those we see. There is a lot of pretty mathematics that would describe such a universe nicely, but that doesn't mean our universe is that way. That said, some theories postulate that there are around 12 spatial dimensions.

This is kind of a difficult thing to understand. If you lived on a perfectly flat plane (a two dimensional world), and I tried to explain to you that there was another dimensions perpendicular to both of yours that I called "up and down", you couldn't possibly understand what I meant. In the same way, we don't have any direct experience of more than three spatial dimensions, so it's very difficult to understand them except by metaphor. There is a classical book that I highly reccomend you read to get a feeling for this.

Tangentially, if you really want to understand physics/cosmology, you have to start at the bottom and work your way up. It's a common misconception that you can sort of get the gist of these weighty ideas without the physics/math prerequisites. I've never found that to be the case, and most people who try end up with ideas like his fellow.

Furthermore, most of the ideas you're discussing are not actually science yet. They're highly speculative. Anyone can propose models that sound cool, but without some background in the established science, it will be hard for you to evaluate their sanity.
posted by phrontist at 11:04 AM on July 11, 2008 [3 favorites]


Believe it or not, none of this is even substance-induced.

Aha! There's your problem right there. Fix that deficiency and the rest will fall into place.
posted by rokusan at 11:07 AM on July 11, 2008 [2 favorites]


Why assume there must be twelve?
posted by ssg at 1:57 PM on July 11 [+] [!]


ssg, we aren't "assuming" a number of dimensions; this is the number that makes sophisticated models of the theoretical early moments of the universe "work". Mass is not a dimension, as it does not describe a possible vector along which a particle may travel.

Perhaps BirdD0g's OP confused the issue, but the 12 dimensions that cosmologists speak of are not the 12 he has listed above. The "extra" 9 dimensions are much more like X, Y, and Z; AFAIK time is the unique non-spatial dimension.

And the other 9 no longer exist, essentially; they are supposed to have collapsed briefly after the Big Bang (as in nanoseconds afterwards).
posted by IAmBroom at 11:07 AM on July 11, 2008


Maybe. But hue is definitely Y in that it runs perpendicular to BRIGHTNESS.
posted by BirdD0g at 1:59 PM on July 11 [+] [!]


I think you're confusing "perpendicular" with "orthogonal". One is a strictly spatial term; the other merely requires that change in one variable does not affect the other variable*.

*OK, not a strict mathematical definition, but I'm trying to focus on the pair of terms here.
posted by IAmBroom at 11:10 AM on July 11, 2008 [1 favorite]


Doesn't time have at least two dimensions in itself?

1. The Diachronic, or what we typically define as time (represented by a timeline).
2. The Synchronic, or all possibility, as in the option to turn left or right when I walk out the door. Both are possibilities along with a zillion other options that create this second axis of time.
3. Stands to reason (in my brain) that their might be a third "orthagonal" axis.

Good call on orthagonal. That's exactly what I mean, and exactly what I'm working with – a three orthagonal theory of sorts.

Musicians: Does sound have any orthagonal axes related to it?
posted by BirdD0g at 11:16 AM on July 11, 2008


Musicians: Does sound have any orthagonal axes related to it?
posted by BirdD0g at 2:16 PM on July 11 [+] [!]


Not a musician... but - yes: pitch & volume are orthogonal (and directly analagous to light's hue & brightness, btw).

You're getting it. But remember: orthogonality "axes" are only pictured as spatial axes for convenience in visualizing the variables. They aren't necessarily physical dimensions.
posted by IAmBroom at 11:20 AM on July 11, 2008


a three orthagonal theory of sorts

Why three? What's your theory?
posted by Blazecock Pileon at 11:21 AM on July 11, 2008


What makes you think the "synchronic" is a dimension of time at all? For that matter, what evidence do you have that the synchronic even exists? Sure, you say you could have turned left instead of right when you walked out the door at 11:43:08, but in fact you did turn right, and there doesn't seem to be any evidence that you could have turned left instead of right, just your claim that you could have. And, of course, if you go out the same door later and turn left, that's not evidence that you could have turned left at the earlier time, only that you did turn left at the later time.

I submit to you that "the synchronic" is a matter for philosophy, not physics, and is not a dimension in the way that "the diachronic" is, which can actually be observed and measured.
posted by DevilsAdvocate at 11:24 AM on July 11, 2008


Spacetime has only one temporal dimension. For possibilies, perhaps you are thinking of things like the many-worlds interpretation of quantum physics. However, the "alternate realities" do not constitute another dimension of spacetime: they are inaccessible to things in this universe.
posted by demiurge at 11:28 AM on July 11, 2008


I think you're being seduced by words, a common modern affliction :-)

First of the "diachronic" dimension of which you speak is an abstraction there is no compelling reason to believe exists physically. I don't know about you, but I perceive time moment by moment, in a constant flow, sandwiched between past a present. I have no direct experience of past or future things. The timeline is a good way to visualize our memories and predictions... but I've never experienced anything to suggest (nor can I think of an experiment to test) the idea that there is a big storehouse of time slices "out there".

It's all well and good to say that there is a "synchronic dimension" of possibility, but again, what would that actually mean? Something like the many worlds interpretation of QM? Couldn't we just as easily say that hyper dimensional squid roll 13-sided dice to determine what takes place in our world? It seems like a non-falsifiable hypothesis.

In addition to Flatland, which is really one of the greatest books ever written, I'd recommend Philosophy of Science: A Very Short Introduction from the Oxford University Press.
posted by phrontist at 11:29 AM on July 11, 2008 [1 favorite]


As far as light and sound go, they are simply specific phenomena that occur within our good ole' 3-dimensional world. Every acoustic or optical phenomena we've observed (with the exception of a few quantum things that some people are happy with for the latter) can be completely described within the mathematical framework of 3-dimensional space.

Sound is nothing more than the movement, the bunching together and spreading apart, in 3 dimensions, of molecules comprising a medium humans can put their ears in. Also, since we generally only consider sound things we can hear, you could make the definition more specific by saying that for it to be sound the bunching and spreading process needs to occur periodically at rates between roughly 20 and 20,000 times per second (these bounds are fuzzy, based on age and genetics, which determine the functioning of your organ of corti). Wind is the movement of air... but it's not happening a rate you can hear it directly (when you hear the wind, you're hearing the turbulence formed near your ears).

Light is a little stranger. In the vast majority cases it's described by Maxwell's equations, which describe all electromagnetic phenomena. So light, magnetism, electricity - they're all the same thing, fundamentally. They're just occurring at different rates. There are some weird cases for which it becomes apparent that classical electromagnetic theory has limitations (just like classical mechanics do), and while some have sought to resolve apparent inconsistencies by postulating extra dimensions, this has yet to be tested.
posted by phrontist at 11:42 AM on July 11, 2008


Maybe. But hue is definitely Y in that it runs perpendicular to BRIGHTNESS.

Hue, saturation, and brightness relate to the way electromagnetic waves interact with your eyes. They don't exist in the sense that space exists as a dimension.

I mean, if you had a black and white camera, then the hue and saturation dimensions wouldn't make any sense. If you had a camera that had more then three types of color sensors, they wouldn't seem the same as what you see.

And actually, people with four color sensors have been found. They can see colors that you can't.

So even between humans, not all color spaces are the same. It's relative to your eyes and nothing more.

Really, other three sets of X Y and Z (time and color) are just nonsense and sound like time cube stuff.
posted by delmoi at 11:44 AM on July 11, 2008 [3 favorites]


ssg, we aren't "assuming" a number of dimensions; this is the number that makes sophisticated models of the theoretical early moments of the universe "work". Mass is not a dimension, as it does not describe a possible vector along which a particle may travel.

I took the exercise to be BirdD0g's somewhat idiosyncratic (perhaps phenomenological) definition of the universe and wondered why s/he had decided on twelve. Nothing to do with the beginning of the universe at all. I'm well aware that mass isn't a dimension (in the conventional sense), but I got a vibe that BirdD0g wasn't using the word "dimension" in the regular sense anyways. I should have made that more clear, as I knew someone would object.
posted by ssg at 11:45 AM on July 11, 2008


that more clear, as I knew someone would object.
posted by ssg at 2:45 PM on July 11 [+] [!]


Guilty as charged. My misunderstanding.
posted by IAmBroom at 11:58 AM on July 11, 2008


If sound's VOLUME is equal to color's BRIGHTNESS (high to low, light to dark) and
sound's PITCH is equal to color's HUE (ABCDEFGA, ROYGBIVR), then

What is equal to SATURATION? I guess it would be whatever going up and down octaves is called?
posted by BirdD0g at 12:08 PM on July 11, 2008


IAmBroom: The measure of the distance across the universe is different than the time the universe has existed. Things like inflation and expansion fouled that up. The universe is 13.7 billion years old.

wfrgms: They use newtonian calculations with relativistic corrections. They are extremely accurate about these things, to the point where relativity does matter.

This idea of a "Synchronic" dimension is just not sustainable. If each "possibility" really did exist in another dimension, the number of dimensions you need would grow exponentially with the number of "possibilities". You're talking the multiverse here, but that should be mixed up with a dimension.

This question is getting awfully far away from any physical meaning.
posted by kiltedtaco at 12:08 PM on July 11, 2008


BirdD0g: Please, don't just make stuff up. If you look up saturation you'll see it's color-specific brightness. So you could measure the brightness of white light (which has a wide array of pure colors within it) and you could also measure the brightness of those components individually.

In a musical analogy, anything but pure sine waves can be decomposed in to sine waves (here is why). The sine waves, just as with light, are the pure constituents of more complicated sounds. So, metaphorically, saturation would just be amplitude for a particular frequency.

Yet again though, these are not "basic" phenomena. They are reducible to simpler ones, and it's misguided to view them as some sort of essential property of the universe, because we know better these days.
posted by phrontist at 12:15 PM on July 11, 2008 [1 favorite]


IAmBroom: The measure of the distance across the universe is different than the time the universe has existed. Things like inflation and expansion fouled that up. The universe is 13.7 billion years old.
posted by kiltedtaco at 3:08 PM on July 11 [+] [!]


Thank you. Duh. I knew better, once.
posted by IAmBroom at 12:36 PM on July 11, 2008


Aren't we overlooking the Law / Chaos and Evil / Good dimensions?
posted by SPrintF at 12:36 PM on July 11, 2008 [3 favorites]


You can't fool me, it's turtles all the way down.
posted by bartleby at 12:41 PM on July 11, 2008


What are the dimensions of the universe?

We don't know. There is no unified theory of physics. There are contradictory theories that work well within their domains, but they cannot be used to discern any dimensions with any confidence, because they contradict each other.

[more inside]

Basically everything else you've said is fiction. If you said that the orthogonal dimension to Jesus was Satan, it would be just as scientific.
posted by East Manitoba Regional Junior Kabaddi Champion '94 at 12:54 PM on July 11, 2008


BirdD0g: I think the closest analogy would be that saturation of a color corresponds to purity of tone. A clear, pure note would correspond to a highly saturated color; a note with a hissy or staticky background would correspond to a less saturated color. This analogy is similar to the one that gives rise to the terms "white noise" (for a spectrally-flat hiss) and "pink noise" (for a hiss with more energy at lower frequencies than higher).

The repeating nature of octaves has to do with the way we like to hear timbre and harmonics. I'd suggest finding a book on musical acoustics— it's a fascinating subject.

Our perception of color is much more limited than our perception of sound, though. It's possible to hear a pair of notes at the same time and still distinguish them, or to say things about the timbre of a note independent of its frequency. But we can't do that with color, or at least not to the same extent. We have three kinds of color receptors in our eyes, which is why our sense of color decomposes neatly into a three-dimensional space (whether those dimensions are hue, saturation, and brightness; or red, green, and blue; or luma and a 2-dimensional chroma value; or many other ways of describing color). We have far more distinct receptors in our ears— each hair cell along the cochlea is responding to a slightly different aspect of the sound. Assigning a number of dimensions to sound is like assigning a number of dimensions to the notion of shape. Mathematically it can be done but it's not an intuitively satisfying thing.

Some humans have more color sensors (tetrachromats, as delmoi mentioned) or fewer (dichromats and monochromats: various kinds of color-blindness). These people would have four, two, or one-dimensional experiences of color. Goldfish are all tetrachromats, as are a number of other common animals. Mantis shrimp have an absurdly large number of color receptors and polarization receptors; compared to their color experience, ours must be like a faded sepia photograph.
posted by hattifattener at 2:06 PM on July 11, 2008


What is equal to SATURATION? I guess it would be whatever going up and down octaves is called?

That's pitch. The fundamental qualities of musical sound are rhythm, pitch, and timbre.
posted by ludwig_van at 4:47 PM on July 11, 2008


...that was an 8734;, or infinity symbol... Now it just says "Approximately equal to 8,734" and I look like a lunatic.

Actually, I think "approximately equal to 8,734" is as good as any other answer we're going to get to this question.
posted by iguanapolitico at 5:09 PM on July 11, 2008


BirdD0g: I think you should consider that you don't understand as much about physics as you think you do, and that much of what you think you are understanding is incorrect.

As Pauli said, "That's not right. It's not even wrong."

I think all of what you're positing about these supposed dimensions is non-sensical.
posted by Justinian at 5:56 PM on July 11, 2008 [1 favorite]


Aw. I was hoping it would stay at 42 comments forever, being oddly appropriate, though I suppose that's little use to the OP.
posted by Solon and Thanks at 1:10 AM on July 12, 2008


If you meant it in a way analogous to "what are the dimensions of the tower case of my computer", it's not strictly speaking a measurable quantity. "The Universe" is everything that is. To measure my computer requires that there is something above, below, left, right, in front and behind it. This is not true of the Universe.

Further discussion on what the expanding Universe is expanding into here; further interesting cosmology stuff here.
posted by aeschenkarnos at 8:06 AM on July 12, 2008


« Older Completely overwhelmed with ch...   |  Has anyone successfully travel... Newer »
This thread is closed to new comments.