I don't see why the idea that "the universe might have been around forever" is so surprising since as far as I know, the prevalent theory is that time started at the big bang, which means that saying "before the big bang" makes as much sense as "going north while standing at the north pole".
But that still isn't the same thing as "forever." Time does not go back infinitely — according to current theory, the universe definitely has a beginning in time.
The whole dimension-tautology has always irked me. Time, as a unit, is simply the "time" it takes for light to travel a certain distance. Distance, OTOH, is the "distance" it takes for light to travel under a certain amount of time. AFAIK one of the authors of this theory is a proponent of a variable speed of light. So if at some point in time light didn't move, then time didn't move, then that would mean that our universe existed since forever...? Not a physicist, but sometimes I feel weird when I am reminded of the fact that the Big Bang had a definite starting point 13.8B years ago (as you have done so), and then think about how time is really... a function of length and length is just a function of time.
No, time is defined in terms of atomic properties. It is not a function of length. (Length is, however, a function of time). A second is defined as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom.
A meter is defined in terms of the speed of light and the definition of a second. A meter is exactly the length of the path traveled by light in a vacuum during a time interval of 1/299,792,458 seconds.
Ah, thanks for that. I look pretty stupid now...I have actually heard of that definition but somehow I was thinking of time being ultimately defined by Planck units (time required for light to travel a Planck length).
The Einstein quote is great. I would add: The only reason for time is so that everything can't be understood at once.
'Stretching' and 'scaling' as the foundational principle of distances and time makes the idea of a starting point needless. I wrote about it here:
http://hashsign.co.uk/contemporary/by/thoughts/pop-pop-bang-...
People find comfort in knowing when something starts, and when something ends. It stems from controlling, wanting control over your environment. You can let that go though, and then the universe being infinite is beautiful.
I think our best guess is that our universe is connected to other universes, perhaps through a larger bubble / body, and perhaps through that connecting through to perhaps infinite other universes.
> the prevalent [in the general public, and therefore in the scientific community] theory
The reason it's prevalent is because it is the most easily understood and acceptable by most people/religions/cultures - not because it is the most accurate or plausible explanation.
I'm not talking about the scientific community. I'm talking about people in the world. Christianity for example has accepted the Big Bang Theory as plausible and has not accepted others. This fact alone will help 70% of the world make a theory more prevalent.
Christianity is a rather broad grouping that encompasses a hundred churches with different beliefs. I don't think you can make meaningful statements about what Christians believe, except that they believe in Christ (hence the name). There's no central planning committee that decides what to believe.
For practical purposes, you may as well just use the word religion, as in "Religion for example has accepted the Big Bang Theory", which is more obviously too general.
This is an anecdotal reposnse mostly based on having grown up in a strongly charismatic Christian background, but the folks I knew probably would have said that god existed forever and the universe started when he made it.
Obviously that's going to depend on who you ask in the denomination and what denomination you ask. My experience is that you're not generally going to get a very nuanced view of space and time but occasionally you'll be a little surprised.
Rewind the tape to 1900. Everyone who is non-religious assumes the universe has been around since forever: it is eternal. Then people like Edwin Hubble and Georges Lemaître notice that distant galaxies are red-shifted, and they calculate the amount. From this they conclude that the universe is expanding. From this they conclude that the universe must have at one point been compressed to a single point, and then exploded: a Big Bang.
But if there is no red shift, then there is no Big Bang, and the Universe is not expanding. Therefore we go back to where we were in 1900, when everyone assumes that the universe is eternal.
Proponents of a static universe have a lot of explaining to do. For example, older galaxies tend to look lumpy and amorphous, because they interacted and collided with other galaxies more often in our early, dense universe. Symmetric elliptical galaxies and our structured Milky Way tend to be younger.
Also, you can have a static universe with a beginning, or an expanding universe with no beginning. Rainbow gravity falls into this latter category.
Glad you too noticed that. I was feeling extremely stupid and ignorant for not having understood the correlation between rainbow gravity and an eternal universe.
The fundamentals seems to be provable by data-mining on gamma Ray bursts.
Funny coincidence, I just started "mining" some BOINC projects again since a week ago, including Einstein@home, because I couldn't stand all the CryptoCoin mining talk lately.
Maybe he's speaking of a much bigger 'local' like 'our corner of the universe' or 'the distance over which our deep space probes have so far traveled'.
I didn't really discuss the Rainbow Gravity Theory. But I referred to the Scientific American article here<br>
http://hashsign.co.uk/contemporary/by/thoughts/pop-pop-bang-...
My statement is: The difference between singularity and the world is differentiation. Differentiation is a kind of 'stretching'. The methods of stretching are called time and dimensions in space.<br>
It's nothing else than a crutch for thinking. 'All at once' is for thinking equal to nothing (singularity).
given that a sensical idea of time couldn't really exist before the universe, i believe it is sound to say that current understandings of the universe already state this.
just that "forever" is 13.8 billion years long and counting..
Life sure but sentient creatures like us using technology, maybe we're the only planet to have survived comets, meteorites, gamma ray bursts, black holes, galaxy collisions, novae to make it this far.
Or might not, no matter how far you go, there are no even numbers in the infinite set of odd numbers, and you can tell that without counting very high.
