Comment by ck2
1 day ago
isn't holographic universe a similar concept to string theory in that they both propose higher dimensions projecting into lower dimensions
string theory, 11 dimensions, is bonkers though, it's what happens when people are too smart for their own good imho lol
No string theory (10d) or m theory (11d) map to lower dimensions (eg 4d) via (generalisation of) Kaluza Klein compactification. Vector boson (eg maxwell or Yang mills) are internal degree la of freedom-> 6/7d graviton becomes a photon/ gluon.
There’s holography in string theory: AdS/CFT but this rather maps 4d super Yang mills (on the boundary of AdS5) in an AdS5xS5 background: which is one holography correspondence we know works.
Holography is much more common, but we only really understand it on hyperbolic spaces.
Also since it has a theory at strong coupling on one side we cannot really do calculation on that side and verify it.
You can use it tho to make calculations.
Many concepts can be framed as projections onto lower dimensions. It’s the specific ways in which things are projected that makes things string theory. IOW don’t mistake the concept of a map for the territory that one type of map describes.
Eh, 11 dimensions is just what the math predicts based on the theory’s postulate and observations of the universe.
Holographic gravity is no less fanciful if there’s no practical experiment to prove it.