Replies

The extra time dimension

A second timelike dimension would have to be folded up to very small size like the other extra dimensions. If the second timelike dimension were similar to the first in size, just orthogonal, it would make too many things possible. If all things are possible, then evolution is dead and change is impossible, so there is a phenomenological contradiction. OTOH it would eliminate the need for the Big Bang.

Thank you so much for your post!

Indeed, the compactification of extra spatial dimensions is an artificial construct.

For instance, under ekpyrotic cosmology, the inception dimensions are deemed parallel and thus, there is no big bang.

Likewise, in 5 dimension space/time such compactification is not necessary:

Welcome to the homepage of the 5D Space-Time-Matter consortium. We are a group of physicists and astronomers working on a five-dimensional version of general relativity. Our work differs from Kaluza-Klein theory (the basis of superstrings) in that we do not assume compactification of the extra dimension. This means that new terms (those involving the 5th coordinate) enter into physics, even at low energies. In 4D spacetime these can be interpreted as matter and energy. We move them to the right-hand side of the 4D field equations and take them to describe an induced energy-momentum tensor. In fact, we have shown that no 5D energy-momentum tensor is required. 4D matter of all kinds can arise as a manifestation of a higher-dimensional vacuum. This is one way to realize Einstein's dream of transmuting the "base wood" of matter into the "pure marble" of geometry -- that is, of unifying the gravitational field, not just with other fields but with its source.

Generally speaking, the objection to extra time dimensions is the aversion of converting from a time line to a plane. Causation is essential to physics as is timeline order (this before that, that after this.)

If our time dimension is a plane and not a line, the past, present and future are all seen at once and the cause/effect can be inverted to effect/cause.

Therefore, IMHO the artificial aversion of science is a prejudice which may stand between us and truth.