Do scientists believe our universe had a beginning?
In spite of a very widely-accepted misconception, the truth is, that the Universe is infinite in space and time. Therefore it does not have a beginning.
The prevailing concept is that the Universe is expanding, from the Big Bang, which marked the beginning of the Universe.
The expansion idea came from the misconception that galactic red shifts were due to the Doppler Effect, from galaxies moving away.
Recent work shows that red shifts cannot be due to Doppler, because they are different at different ends of the same spectrum. If you can find a scientist who can explain this away with Doppler, good luck.

Fred Hoyle and the Big Bang
There's a fuller explanation in a YouTube video:
Science Myth Busting Episode 02 -- Big Bang. With David Noel. .
Or a detailed article at:
UG106: R.I.P. Expanding Universe (b. 1930, d. 2012): (The Big Bang never happened) .
Or a ten-line summary at:
How old is the Universe? .
Item: LT220413
Perth, Western Australia.
Last update 2025 Nov 28.