# How Many Dimensions Are There? **URL:** \ **Category:** Factual Questions\ **Created:** [January 22, 2018, 4:00pm UTC](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215 "2018-01-22T16:00:33Z")\ **Posts on this page:** 20\ **Page:** 4
**Author:** ![Itself](https://avatars.discourse-cdn.com/v4/letter/i/d07c76/32.png) [@Itself](https://boards.straightdope.com/u/Itself)\ **Post date:** [January 30, 2018, 5:04am UTC](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215/61 "2018-01-30T05:04:33Z")
> [@rat\_avatar](#): > > Please provide a cite that has demonstrated the existence of five-dimensional space or n-dimensional space as a as a physical entity. What I actually said was: > [@](#): > > We could be living in a Poincare sphere, on a 10+1 dimensional space filled with superstrings, or something else more complicated. We may not be, but the fact that we don’t see those effects in ordinary experience doesn’t somehow invalidate them, any more than the fact that driving to work doesn’t involve QED means that that theory is nonsense. As for the rest of it, you seem like you really want to talk about the efficacy of modern theoretical high-energy physics, but that’s not what this thread is about. ---
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [January 30, 2018, 5:15am UTC](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215/62 "2018-01-30T05:15:48Z")
> [@Itself](#): > > What I actually said was: > > As for the rest of it, you seem like you really want to talk about the efficacy of modern high-energy physics, but that’s not what this thread is about. Invoking a claim of it being physics, and I need to help correct GQ responses. But talking about overloaded terms, it is Theoretical physics but it is not a physics theory. A theory by definition, is a coherent group of **tested** general propositions, commonly regarded as correct, that can be used as principles of explanation and prediction for a class of phenomena. But if you go back to look at my post you will see I was responding to: > [@Exapno\_Mapcase](#): > > Hmm. There’s what you say and what actual working physicists say. Which to pay attention to? Such a problem. When you were talking about parameter spaces or configuration spaces and not the minimum number of coordinates needed to specify any point within a space. If you are going to claim that physics doesn’t care about experiments and tests I will refute that. Anyway, your example included dimensions of convenience, three spatial dimensions and three angles of rotation can be simplified to cartesian coordinate system when string theory requires extra dimensions of spacetime for mathematical consistency. These overloaded terms suck, but string theory is a theoretical framework and not a accepted physics theory and until it can even be tested it never will be. ---
**Author:** ![Itself](https://avatars.discourse-cdn.com/v4/letter/i/d07c76/32.png) [@Itself](https://boards.straightdope.com/u/Itself)\ **Post date:** [January 30, 2018, 5:31am UTC](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215/63 "2018-01-30T05:31:20Z")
> [@rat\_avatar](#): > > Invoking a claim of it being physics, and I need to help correct GQ responses. You’re not helping. Here are the main points: 1. What mathematicians and physicists call a dimension is, loosely, a degree of freedom in some nice configuration space. 2. The question of “how many dimensions does the universe have?” is asking about the dimension of space-time. In the Newtonian case, there are three space-time dimensions, which behave as one expects. In the special relativistic case, there are 3+1 dimensions and a nontrivial coupling (for a lack of more technical terms) between the space dimensions and the time dimension. In the general relativistic case, space-time is a 4-dimensional manifold with more complicated structure. 3. More exotic theories propose extra dimensions; for example, bosonic string theory and superstring theory involve 10+1 and 25+1 dimensions, respectively. 4. We’re all aware that we only see three flat spatial dimensions in ordinary situations. That’s not inherently a problem; we’re talking about a more complicated manifold structure than just R^N for large N. ---
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [January 30, 2018, 5:44am UTC](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215/64 "2018-01-30T05:44:28Z")
> [@Itself](#): > > You’re not helping. Here are the main points: > > 1. What mathematicians and physicists call a dimension is, loosely, a degree of freedom in some nice configuration space. > 2. The question of “how many dimensions does the universe have?” is asking about the dimension of space-time. In the Newtonian case, there are three space-time dimensions, which behave as one expects. In the special relativistic case, there are 3+1 dimensions and a nontrivial coupling (for a lack of more technical terms) between the space dimensions and the time dimension. In the general relativistic case, space-time is a 4-dimensional manifold with more complicated structure. > 3. More exotic theories propose extra dimensions; bosonic string theory and superstring theory involve 10+1 and 25+1 dimensions, respectively. > 4. We’re all aware that we only see three flat spatial dimensions in ordinary situations. That’s not inherently a problem; we’re talking about a more complicated manifold structure than just R^N for large N. Yet you hand wave away a cite from a credentialed professional particle physicist, and the question on this page. > [@Scylla](#): > > Chronos: > But extra dimensions and alternate universes are heady stuff, and people think these models are literal. > > It doesn’t help when people who should know better claim they are real. I know, I know, calculus is real and a 5 dimensional signal model of beer that provides useful data is real, but neither is literal. For a physicist there is one and only one criterion to believe in the correctness of a physical theory - whether or not it passes some observational or experimental test. As this is GQ, please provide a single observational or experimental test that string theory has passed, and think about Scylla’s question. **Believing** is unscientific and not “physics” as you Claim. GR is not perfect, but all tests including Frame-dragging, gravitational waves and equivalence principle which all depend on a 4 dimensional curved spacetime have passed. If you are going to claim that the extra dimensions of string theory are _real_ and that people should believe in them without a single observational or experimental test you are not practicing hard science. I could claim a particle called phlogiston is contained within combustible bodies and released during combustion and rusting, is the principal agent in fermentation and is responsible for colors. People may believe me for 100’s of years, but if it cannot meet the current standards they shouldn’t. Once again, string theory may be true, but to _believe_ in it right now is improper, but I hope people continue to dream about it, think about it and to try to prove it. This may seem like sophistry, but people are being confused about the core tenants of the hard science. ---
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [January 30, 2018, 5:49am UTC](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215/65 "2018-01-30T05:49:53Z")
I should note that Newtonian model was disproven not by Einstein’s claims, but because his claims were back by observational or experimental data. The predictions made by GR were **verified** and that is why we replaced the older, less accurate Newtonian model with a 4-dimensional manifold called spacetime. We didn’t just accept his theories based on _faith_, which is what you are asking for. And yes, these experiments were verified; most to five sigma. ---
**Author:** ![Itself](https://avatars.discourse-cdn.com/v4/letter/i/d07c76/32.png) [@Itself](https://boards.straightdope.com/u/Itself)\ **Post date:** [January 30, 2018, 5:50am UTC](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215/66 "2018-01-30T05:50:12Z")
I don’t know what to tell you, man. Hopefully that person who’s making the claims you describe will read your post and realize the errors of his ways. As for me, I’m pretty sure I’m aware of what physics is and what physicists do, but thanks for the heads-up! > [@rat\_avatar](#): > > We didn’t just accept his theories based on _faith_, which is what you are asking for. Cool story, bro. :rolleyes: ---
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [January 30, 2018, 5:53am UTC](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215/67 "2018-01-30T05:53:32Z")
> [@Itself](#): > > I don’t know what to tell you, man. Hopefully that person who’s making the claims you describe will read your post and realize the errors of his ways. As for me, I’m pretty sure I’m aware of what physics is and what physicists do, but thaniks for the heads-up! Provide a cite, if physics as a field doesn’t required observational or experimental tests it should be easy to prove. ---
**Author:** ![Itself](https://avatars.discourse-cdn.com/v4/letter/i/d07c76/32.png) [@Itself](https://boards.straightdope.com/u/Itself)\ **Post date:** [January 30, 2018, 5:55am UTC](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215/68 "2018-01-30T05:55:15Z")
> [@rat\_avatar](#): > > Provide a cite, if physics as a field doesn’t required observational or experimental tests it should be easy to prove. I’m not going to provide a cite for something I’m not even saying. Go bother someone else. ---
**Author:** ![Scylla](https://avatars.discourse-cdn.com/v4/letter/s/a5b964/32.png) [@Scylla](https://boards.straightdope.com/u/Scylla)\ **Post date:** [January 30, 2018, 2:23pm UTC](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215/69 "2018-01-30T14:23:02Z")
> [@Itself](#): > > For a concrete example, take the configuration space of a classical rigid body. It has six dimensions: three spatial dimensions and three angles of rotation. The latter are perfectly valid, even though they’re measured in different units than the former. > > Well, that’s the thing: We _don’t_ actually live in that kind of space. We live in a space that looks a lot like what you describe if you’re putting together a fish tank or walking slowly. If you’re working with GPS, MRI machines, superconductors, cosmic rays, or any of a larger variety of activities, that approximation is no longer sufficient. If you tell me that a fish tank measures 3 meters in length, that’s great if I’m standing next to you on earth, but I’m not going to get the same result if I’m travelling close to the speed of light and relativistic effects become significant. You might complain that that isn’t a case most people deal with in their ordinary lives, but that doesn’t make it any less valid or real. No one’s arguing that classical approximations aren’t useful, but they aren’t the full picture. Objects have 3 dimensions. If you know those three dimensions you know the shape and size of them, and in a way “know” them. This dimensions as a key to knowledge thing, means the word gets used differently in other applications. If a problem has 6 things that we care about and most know in order to work it than that problem has 6 dimensions. In the problems that you describe we can care about more than just the size and shape of something but also it’s relative axes and velocities and distances etc. in that sense we are adding dimensions. A mathemetician can note that we don’t have to treat these added dimensions any differently than the classic spatial ones, and that none is more important than any other. Therefore he concludes, that they are all the same and equally valid, and from his perspective of working on a model of a problem they are. The problem is that he is using spatial dimensions interchangeably with those built into a model, and assuming that what is in his model is a reflection of what really is. They are not interchangeable and the model does not create reality. ---
**Author:** ![Itself](https://avatars.discourse-cdn.com/v4/letter/i/d07c76/32.png) [@Itself](https://boards.straightdope.com/u/Itself)\ **Post date:** [January 30, 2018, 3:23pm UTC](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215/70 "2018-01-30T15:23:36Z")
I don’t know what else to tell you that hasn’t already been covered by many people in this thread. The dimension of a thing is, loosely speaking, the number of independent parameters at a given point. In special and general relativity, spacetime is a (3+1)-dimensional manifold. In more exotic theories, it’s (10+1)- or (25+1)-dimensional. There’s really not much more to say. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [January 30, 2018, 3:49pm UTC](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215/71 "2018-01-30T15:49:37Z")
> [@](#): > > Objects have 3 dimensions. If you know those three dimensions you know the shape and size of them, and in a way “know” them. You need a lot more than 3 dimensions to know the shape and size of an object. If I tell you that an object is five meters long, two meters wide, and three meters tall, is that three aluminum poles joined together at right angles, or a 720-ton block of solid concrete? ---
**Author:** ![Scylla](https://avatars.discourse-cdn.com/v4/letter/s/a5b964/32.png) [@Scylla](https://boards.straightdope.com/u/Scylla)\ **Post date:** [January 30, 2018, 4:06pm UTC](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215/72 "2018-01-30T16:06:04Z")
> [@Chronos](#): > > You need a lot more than 3 dimensions to know the shape and size of an object. If I tell you that an object is five meters long, two meters wide, and three meters tall, is that three aluminum poles joined together at right angles, or a 720-ton block of solid concrete? Not “know” in a godlike sense. There will always be more to a physical object than is contained in any description. No matter how many dimensions one uses, there is more to an object than the description. But, if you tell me you have a block of concrete 5x2x3, you’ve given me a lot of information and in that sense I know what you are talking about, and in that sense “know” it. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [January 30, 2018, 4:34pm UTC](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215/73 "2018-01-30T16:34:03Z")
I’m technically a social scientist. We do research by studying human behavior and discovering patterns. Here’s the result of some research I have conducted, confirmed by dozens of examples over many years. When a thread has gone through three rounds of “I said,” “I said,” the thread will never get any further. Neither side will convince the other, neither side will back down. Every post after that is a waste of time as an argument. (Some interesting facts may emerge as partial recompense, but that’s not a guarantee.) If this thread continues I’ll come back to see how well my prediction does. ---
**Author:** ![Quercus](https://avatars.discourse-cdn.com/v4/letter/q/7ab992/32.png) [@Quercus](https://boards.straightdope.com/u/Quercus)\ **Post date:** [January 30, 2018, 5:28pm UTC](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215/74 "2018-01-30T17:28:08Z")
> [@Exapno\_Mapcase](#): > > I’m technically a social scientist. We do research by studying human behavior and discovering patterns. Here’s the result of some research I have conducted, confirmed by dozens of examples over many years. > > When a thread has gone through three rounds of “I said,” “I said,” the thread will never get any further. Neither side will convince the other, neither side will back down. Every post after that is a waste of time as an argument. (Some interesting facts may emerge as partial recompense, but that’s not a guarantee.) > > If this thread continues I’ll come back to see how well my prediction does. Isn’t there an Internet Law that says 95% of on-line arguments are really just about the definition of a word? ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [January 30, 2018, 5:38pm UTC](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215/75 "2018-01-30T17:38:04Z")
> [@Quercus](#): > > Isn’t there an Internet Law that says 95% of on-line arguments are really just about the definition of a word? Probably. “Dimension” seems to be the point of contention here. (Which makes me wonder how wonder how dimensions are applied to pointlike elementary particles but I’m not dropping that crouton into this word salad.) ---
**Author:** ![Itself](https://avatars.discourse-cdn.com/v4/letter/i/d07c76/32.png) [@Itself](https://boards.straightdope.com/u/Itself)\ **Post date:** [January 30, 2018, 5:42pm UTC](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215/76 "2018-01-30T17:42:58Z")
> [@Exapno\_Mapcase](#): > > When a thread has gone through three rounds of “I said,” “I said,” the thread will never get any further. Neither side will convince the other, neither side will back down. Every post after that is a waste of time as an argument. (Some interesting facts may emerge as partial recompense, but that’s not a guarantee. Right, but don’t draw a false equivalence between the two sides. The physicists here are squarely on a single side, and the terms that people are arguing about the meanings of are well-defined technical terms in physics. This is a factual question, not a Great Debate. Nevertheless, i don’t know what else to say. The OP asked a factual question, and he’s gotten his factual answer. Cool. ---
**Author:** ![rat\_avatar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rat_avatar/32/255_2.png) [@rat\_avatar](https://boards.straightdope.com/u/rat_avatar)\ **Post date:** [January 30, 2018, 6:07pm UTC](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215/77 "2018-01-30T18:07:48Z")
> [@Itself](#): > > Right, but don’t draw a false equivalence between the two sides. The physicists here are squarely on a single side, and the terms that people are arguing about the meanings of are well-defined technical terms in physics. This is a factual question, not a Great Debate. > > Nevertheless, i don’t know what else to say. The OP asked a factual question, and he’s gotten his factual answer. Cool. I looked through the thread for a cite on a “factual answer”, can you help me understand by pointing out one that demonstrates that a prediction can be made that requires more that 3 spacial and 1 temporal dimension? While those 3 spacial and 1 temporal dimensions are also an artifact of convention, I am unaware of any known test that requires higher dimensional counts that are indescribable without them. Full disclosure, I would personally tend to not use the term “fact” to describe an incomplete theory or hypothesis. ---
**Author:** ![Itself](https://avatars.discourse-cdn.com/v4/letter/i/d07c76/32.png) [@Itself](https://boards.straightdope.com/u/Itself)\ **Post date:** [January 30, 2018, 6:14pm UTC](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215/78 "2018-01-30T18:14:55Z")
I don’t know what you think I said, but I’m done talking to you. Go away. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [January 30, 2018, 6:23pm UTC](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215/79 "2018-01-30T18:23:57Z")
> [@Itself](#): > > Right, but don’t draw a false equivalence between the two sides. The physicists here are squarely on a single side, and the terms that people are arguing about the meanings of are well-defined technical terms in physics. This is a factual question, not a Great Debate. > > Nevertheless, i don’t know what else to say. The OP asked a factual question, and he’s gotten his factual answer. Cool. Have the people arguing against the mathematicians and physicists ever been right in any thread? Rightness doesn’t matter. When one side repeats their claims essentially verbatim without offering any additional evidence the thread is over. The thread can be about physics or fast food. The side can be one person or many. The overall pattern is always the same. If you spot it, get out after round three. ---
**Author:** ![Itself](https://avatars.discourse-cdn.com/v4/letter/i/d07c76/32.png) [@Itself](https://boards.straightdope.com/u/Itself)\ **Post date:** [January 30, 2018, 6:31pm UTC](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215/80 "2018-01-30T18:31:25Z")
> [@Exapno\_Mapcase](#): > > Have the people arguing against the mathematicians and physicists ever been right in any thread? Rightness doesn’t matter. When one side repeats their claims essentially verbatim without offering any additional evidence the thread is over. The thread can be about physics or fast food. The side can be one person or many. The overall pattern is always the same. If you spot it, get out after round three. Ok, that I can agree with. As much as I like discussing physics, there’s nowhere else to go from here. (For what it’s worth, I’d recommend the stackexchange sites for physics questions like this one and the one you mentioned earlier about the dimension of point particles. Having single-post answers you can up- and down-vote makes them actually useful, rather than just an endless stream of, “But, but…”) [Previous page](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215.md?page=3) [Next page](https://boards.straightdope.com/t/how-many-dimensions-are-there/807215.md?page=5)