This one’s probably been argued to death , but I cannot find a specific reference in the archive , so :
My humble understanding is that :
1.Big Bang theorists claim that the Universe exploded into existence from an infinitely small , dense mass.
2.Steady Staters claim(ed) that the Universe has always existed.
To me , “always” means since the beginning of time.
Professor Paul Davies says that it is illogical to consider what happened “before” the Big Bang , as time came into being because of the Big Bang.
So , if time began when the universe began , is it not reasonable to conclude that the Universe has “always” existed - in which case the Big Bangers and the Steady Staters would be in agreement ?
No, because the big bang posits an origin to time itself: approx12-20 bil yrs ago IIRC. The steady state says that past time is infinite.
Also the two theories have many other differences. The steady state theory posits a continuous creation of matter to account for the expanding universe, while the expanding universe is a consequence of the big bang.
I don’t think anyone seriously holds the steady state theory any more.
You have made a very valuable insight, Lampokey (welcome BTW!), but the “always” of the timeless singularity-type-object is a little different to the “always” proposed by Steady Staters. In their model, there is no “place” in the universe where time has no meaning - the “line of time” stretches back infinitely. In currently accepted cosmology, the line stretches back to a certain point and then kind of “changes direction” so that it isn’t time any more (although it might be something “timelike”).
The main reason for discounting the Steady State theory is the discovery in 1929 by Ed Hubble that all galaxies are moving away from us (light from every observed galaxy is red-shifted, ie. lowered in frequency like the sound of an ambulance moving away from you), whereas the Steady State would predict a random spread of stationary (no frequency shift), approaching (“blue-shifted”, like the ambulance sound approaching) or receding (red-shifted) galaxies.
This took quite some time to become accepted, during which Steady Staters like Fred Hoyle ridiculed the idea by asking “What, so you expect us to believe that the origin of the universe was some king of Big Bang or something?!”. This term of lighthearted derision gradually became the standard nomenclature - a shame IMHO since it misleadingly implies an “event” (which requires time!) rather than a “place”.
Incidentally, Steady Staters haven’t given up the ghost yet. However, they admit that the expansion of the universe is a real observation (illusory or not) which must be explained by any new theory.
Not to nitpick, but technically only the redshift has been observed. The expansion of the universe is only viewed as the most reasonable explanation of said observation.
Steady state and big bang applies to two seperate and distinct classes of cosmologies, so no they are not the same. It’s just a matter semantics to say that they agree that the universe has always existed. There are a few steady-state supporters left but most of these are from the days before the big bang gained universal accetance.
SentientMeat, are you sure that all galaxies are red-shifted, I don’t know Andromeda’s Doppler shift, but we’re on a direct collision course with it, so I suspect it is blue-shifted.
There are modified Steady State ideas that suggest that cosmic expansion is caused by the (slow!) continuous creation of matter: every so often, a hydrogen atom, along with a cubic centimeter of empty space, pops out of nowhere, and that kinda pushes all the other nearby space away from it.
Fatal flaw: galaxies live too long for this alone to be an explanation for the observed red shift.
I suggest the possibility that there might be other Big Bang “Universes”.
Time for our Big Bang “Universe” may have started at our Big Bang, but “time” existed in the “Universal” Universe.
We discussed this in the other thread that Sentient has linked to. It’s certainly possible that other timelines exist; in fact I believe that’s the central idea of the “many worlds” interpretation of data from experiments in quantum physics. But unless I’m mistaken, we currently don’t have any way to determine whether they exist or not, so it’s pure conjecture at this point. And while I suppose there could be some sort of hierarchical structure to these multiple universes, where there is a “main” universe with its own transcedent timeline, it just seems like the wildest of speculation. And the thing is, according to the big bang model, there would be a disconnect between our time and any other timelines, so events in the other timelines (call it “before” the big bang if you like, although it seems meaningless to do so) could not have any effect on events in our timeline. To post part of my Stephen Hawking quote from the other thread:
In addition to what blow said, I don’t think it is really helpful to put “time” in inverted commas when speaking about these other domains. That they may have timelike properties is possible, but I believe that the word time and all of its associations (before, event, change, begin, cause etc.) should be strictly confined to our universe since we do not, perhaps cannot, know the nature of these other domains.
Steady State says that time had no beginning. Their “always” is philosophically “longer” than "since the beginning of time. It’s like this:
Big Bang: Useful numbers start at zero, that’s the “Beginning of time”. Anything before zero is defined as “undefined”.
Steady State: Useful numbers go back before zero infinitely.
Of course, I’ve no doubt that somebody will take my analogy in exactly the wrong way and natter on inanely about how I’m trying to insult Big Bang proponents by saying they don’t understand negative numbers or some other nit will natter on inanely about how negative numbers really are useful. I really ought to give up on metaphor and simile, but I can’t help myself.