There is a category that groups time, space, and matter together. This category is called "substance" or "substantivalism." I am wondering if there are speculative ideas of something as fundamental as time, space and matter that may not exist in our universe, but may exist elsewhere.

In speculative scenarios, it is challenging to determine definitively what could be as fundamental as time and space in other universes, precisely because our understanding is rooted in our own unique cosmic environment. Speculating about such fundamental concepts is an intriguing intellectual exercise that pushes the boundaries of our imagination and understanding. However, the ultimate nature of such concepts in other universes remains speculative and subject to ongoing exploration and philosophical discussion. However, I am not aware of any attempt at even imagining or conceiving such ideas.

To me, it's impossible, because we can't understand time or space without experiencing it, so likewise, if there are things as fundamental, then we would need to experience them in order to speculate or think about them.

  • A substance is an object that exists independently rather than dependently. So for example, a statue would be a substance, the shape of the statue would not. I doubt anyone would say that matter is a substance because matter, as a generic term, isn't an object. Time and space would only be considered substances if someone were thinking of them as things rather than relations. Commented Aug 5, 2023 at 17:15
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    @DavidGudeman matter has usually been understood as a sort of substance, e.g. in the Transcendental Dialectic Kant writes, "It would indeed be surprising, if the conception of substance, which in other cases requires so much labour to distinguish from the other elements presented by intuition—so much trouble, too, to discover whether it can be simple (as in the case of the parts of matter), should be presented immediately to me, as if by revelation, in the poorest mental representation of all." C.f. Descartes' equation of space and matter. Commented Aug 6, 2023 at 3:05
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    @DavidGudeman however, more in line with your considerations, we could also trace the word "substance" back through Boethius (for whom a person is a rational substance) and the word "hypostasis" to Tertullian (except that Tertullian's proto-Trinitarianism was that the Father was made of His own special matter, and the other divine persons were special extensions of that matter). Commented Aug 6, 2023 at 3:32
  • @KristianBerry, in that quote, Kant is saying that the parts of matter are substances, not matter as a type of material. I've tried to explain this here before: in modern terminology, "substance" refers to stuff or material like gel or wood or concrete. In philosophy, it refers to a thing like a person or a statue. Commented Aug 6, 2023 at 15:29
  • @DavidGudeman the SEP article on substance includes clear references, by philosophers, to matter-as-substance, e.g. Aristotle has matter (along with form and form-and-matter) as such, or Descartes has matter and mind as two types of substance, or Hume equates substance with prime matter, etc. Commented Aug 6, 2023 at 15:51

3 Answers 3


Modern physics posits for example a quantum field. That is fundamental, but is not space, time, or matter. David Bohm also suggested the idea of an "implicate order", which would be a structure in which events are related, but which is not time, space, or matter (cf. wikipedia).

Also, I would urge you not to be too certain about "what we experience". Think: Do we right now experience that quantum field? Well, that is quite an undecidable question, is it not? In the same manner, we also aren't directly aware of that time which stretched from the past to the future or that 3D-space that we think in terms of in our everyday lives. This becomes really visible considering the difference between Newton and Einstein: What do we experience? 3D space, or 4D spacetime?

Yet we "love" arguing about those - constructions, as if they were the real deal.


Negative mass is well defined and well understood theoretically, and probably doesn't exist.

"Exist" and "not in our universe" are concepts that feel like they must mean something together, but probably don't.


Do you mean Can there be different laws of physics which hold elsewhere?

we can't understand time or space without experiencing it

I disagree that we can't imagine things without experiencing them, though I do picture our mathematical intuitions as based on our necessarily shared experiences, discussed here: The Unreasonable Ineffectiveness of Mathematics in most sciences

Consider String Theory and the attempt to understand an 11 dimensional model of a hyper-multiverse (I liked this humorous suggestion I heard: "what are these fabled dimensions that exist after length width and height?" "Bridth, leight, hength, breight, brength, lidth, hidth and hedth. There you go - eleven.").

E8 Theory is a picture of a cosmos with all possible variations of the fundamental constants, with our universe pictured as like a fracture plane within it.

We may not be able to access qualia of a higher-dimensional being, but there are certainly ways to make inferences and imagine things about them. Issues discussed here: Is it possible to visualize higher dimensional space?

I don't think your question is very clear. In Quantum Field Theory we have fields and local excitations of them which the fields can act on. That is matter, particles. We expect space and time to be quantised in some way, probably at the Planck Length. Or Loop Quantum Gravity pictures a spin-lattice network, with spacetime and matter emergent from it. Probably we can't think really clearly about alternatives to space and time until we know in a deeper way what they are (conundrums ofctime laid out here: Understandable definition of time), but we can use Noether's Theorem and symmetry groups to investigate mathematically the consequences of different assemblies of dimensions.

  • No, because physics is something that we can experience or observe (partly). I am talking about something as fundamental as space and time.
    – Sayaman
    Commented Aug 5, 2023 at 17:02
  • @Sayaman: No - we can't go beyond what we experience? What about, mathematics? As I say, I don't think your question is very clear. Did you open that first link?
    – CriglCragl
    Commented Aug 5, 2023 at 17:36
  • I thought it was clear, maybe remove matter from the question, because I don't think matter is as fundamental as space and time, but there doesn't seem to be any work that suggested the possible existence of a third, fourth, fifth fundamental element in a different universe from ours.
    – Sayaman
    Commented Aug 6, 2023 at 13:49
  • @Sayaman: Spacetime is just a set of continuous symmetries, a la Noether's Theorem. & there are other sets. I think you are failing to understand my answer.
    – CriglCragl
    Commented Aug 6, 2023 at 15:44

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