Can a universe exist without matter?

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A universe can theoretically exist without matter, consisting solely of time, space, and energy, such as in scenarios involving radiation or pure gravity. In classical General Relativity, vacuum solutions demonstrate that a universe can be described without matter. However, the implications of quantum gravity complicate this understanding, raising questions about the nature of existence in such a universe. Alternate dimensions often depicted in media suggest the possibility of matter-less universes, though their observability remains a challenge. The discussion highlights the intriguing yet complex nature of universes devoid of matter.
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Just including time, space and energy, but no matter?
 
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If by "can a universe exist" you mean "does a consistent classical GR description exist", then yes you can have a universe with energy (just radiation) but no matter, or you can even have a universe with just pure gravity - a so-called vacuum solution.
 
But what if in quantum gravity?
 
Yes, Space Time and Energy, that's what most things consist of such as the unverse. Matter makes up parts of the unoverse such as our solar system and our planet. Think of alternate dimensions that you here of on TV or in Movies. They sometimes have no matter but yet they exist. This topic can be tricky but yes i pretty sure you can have a universe with no matter.
 
Why is that even interesting, if it's inherently impossible to observe or verify?
 
Duplicate thread.
 

Thread 'Illuminating Black Hole Shadows with Dark Matter Annihilation'

Abstract The Event Horizon Telescope (EHT) has significantly advanced our ability to study black holes, achieving unprecedented spatial resolution and revealing horizon-scale structures. Notably, these observations feature a distinctive dark shadow—primarily arising from faint jet emissions—surrounded by a bright photon ring. Anticipated upgrades of the EHT promise substantial improvements in dynamic range, enabling deeper exploration of low-background regions, particularly the inner shadow...
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Thread 'Matter density right after the decoupling'

https://en.wikipedia.org/wiki/Recombination_(cosmology) Was a matter density right after the decoupling low enough to consider the vacuum as the actual vacuum, and not the medium through which the light propagates with the speed lower than ##({\epsilon_0\mu_0})^{-1/2}##? I'm asking this in context of the calculation of the observable universe radius, where the time integral of the inverse of the scale factor is multiplied by the constant speed of light ##c##.
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