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Barring the terrible style of the article, I think the concept of a mirror universe is not difficult to understand. If we take our three spacial dimensions, an
by mikorym 7y ago
Barring the terrible style of the article, I think the concept of a mirror universe is not difficult to understand.
If we take our three spacial dimensions, and add another time dimension, then we can do a reflection at t=0 and this will produce a mirror object of everything from t>0 at t<0. (Note that in three dimensions, if we perform a reflection it is the same as a rotation when we add a fourth dimension, meaning we can do this "mechanically" if that is worth anything to you.)
This universe at t<0 looks exactly the same as our universe at t>0, except that you switch chirality (or left and right if you will). Now my toy example does not have exotic matter (abundance) differences and also cannot comment at things at the speed of light. In that sense it is Euclidean or perhaps Newtonian.
But what is interesting is that this toy example gives us a concrete way to understand right and left. You can choose anything to call left and anything to call right. But the side at which your heart is of your body will be switched at t<0. Additionally, and this is the only part that I find important or useful, we have actually partitioned things now according to whether they internally define left and right in the usual way or in the opposite way. And finally, we can even now say that subatomic particles that decide to decay as matter or antimatter now self-identify themselves for us and their choice of chirality determines their position at either x > 0 or -x < 0.
EDIT: Disclaimer: I am a mathematician, not a physicist.
- simonh 7y agoWe can imagine all sorts of arbitrary transformations of our universe into various geometrical forms, but they're just imaginary. What turns speculation like this into physics is a mechanism.
- mikorym 7y agoYes sure, that's true. But what my toy example does provide a way to understand chirality and what it means to switch chirality. As far as I can tell, mathematics is agnostic with regards to chirality. But we can partition into two sets the universe of objects according to their internal resolution of their choice of a left/right axis. We will know then that all the ones in t>0 and t<0 are grouped together, respectively, but we don't know which is the set t>0 and which is t<0 as they both look exactly the same.
- invertOfSugar 7y agoYou would have to account for the fact that the earth is moving around the sun, the sun around the galactic core, and so on. Their time backwards is our time forwards, but penguins at the south pole, polar bears at the north pole, and all the birds in every tropical jungle near the equator will watch the moon and the stars spin across the sky, as evolutionary eons pass. If we pass through some kind of temporal lens, and at the zero crossing, we come to understand the other side is an equal but opposite negation of ourselves, a look into the temporal mirror still doesn’t unlock the future. We’ll only catch an alternative perspective of now, and we also can’t do much to treat the mirror like furniture. There’s only one arrow of time, and the reflection isn’t separate and distinct just as shadows are anymore separate and distinct from the objects that cast them.
- nabla9 7y agoPhysicists have considered two time dimensions, but it seems that 3+1 spacetime is 'priviledged'. Here is a chart showing properties of n+m-dimensional spacetimes https://en.wikipedia.org/wiki/File:Spacetime_dimensionality.svg https://en.wikipedia.org/wiki/File:Spacetime_dimensionality.... This article speaks about mirror universe that exists in the same 3+1 dimensional space-time as ours. It's just that the two are transparent to each other. Only gravity ties them together.
- lukev 7y agoIf this concept is interesting to you, Greg Egan has written an entire scifi novel (Dichronauts) set in a 2+2 universe. Weirdness abounds, but quite rigorous.
- Jach 7y agoWas going to highlight that book too. It's also helpful / fun to explore the articles and visualizations outside the book either before/during/after reading it. https://www.gregegan.net/DICHRONAUTS/DICHRONAUTS.html https://www.gregegan.net/DICHRONAUTS/DICHRONAUTS.html
- Aardwolf 7y agoA 3+0 spacetime is described as "unpredictable (elliptic)". What is an intuitive explanation of what being in a 3+0 spacetime would be like? Since there's no time, nothing can "happen"...
- quintushoratius 7y agoOr everything happens, it just happens all at once. Imagine a 3D object squashed between two glass plates until it's a single plane. You can see everything without changing focus.
- vokep 7y agoCurious if a graph like this has been produced considering fractal dimensions? Or would that just be nonsense? I see "We are here" and think...well, sorta, but if the graph were continuous we're at exactly (3.0,1.0) or so it seems.
- pushpop 7y agoIn this mirror universe, do the men have goatees and compassion is seen as a weakness? If so, I have a few theories on how we can find that universe...
- orbifold 7y agoWell it can’t be quite as simple because in GR you don’t have necessarily a globally consistent arrow of time.
- mikorym 7y agoThat's why the toy example is described as "Euclidean".