Posted on 04/24/2018 10:57:04 AM PDT by ETL
At 13.8 billion years ago, our entire observable universe was the size of a peach and had a temperature of over a trillion degrees.
That's a pretty simple, but very bold statement to make, and it's not a statement that's made lightly or easily. Indeed, even a hundred years ago, it would've sounded downright preposterous, but here we are, saying it like it's no big deal. But as with anything in science, simple statements like this are built from mountains of multiple independent lines of evidence that all point toward the same conclusion — in this case, the Big Bang, our model of the history of our universe.
But, as they say, don't take my word for it. Here are five pieces of evidence for the Big Bang:
#1: The night sky is dark
Imagine for a moment that we lived in a perfectly infinite universe, both in time and space. The glittering collections of stars go on forever in every direction, and the universe simply always has been and always will be. That would mean wherever you looked in the sky — just pick a random direction and stare — you'd be bound to find a star out there, somewhere, at some distance. That's the inevitable result of an infinite universe.
And if that same universe has been around forever, then there's been plenty of time for light from that star, crawling through the cosmos at a relatively sluggish speed of c, to reach your eyeballs. Even the presence of any intervening dust wouldn't diminish the accumulated light from an infinity of stars spread out over an infinitely large cosmos.
Ergo, the sky should be ablaze with the combined light of a multitude of stars. Instead, it's mostly darkness. Emptiness. Void. Blackness. You know, space.
The German physicist Heinrich Olbers may not have been the first person to note this apparent paradox, but his name stuck to the idea: It's known as Olbers' paradox. The simple resolution? Either the universe is not infinite in size or it's not infinite in time. Or maybe it's neither.
#2: Quasars exist
As soon as researchers developed sensitive radio telescopes, in the 1950s and '60s, they noticed weirdly loud radio sources in the sky. Through significant astronomical sleuthing, the scientists determined that these quasi-stellar radio sources, or "quasars," were very distant but uncommonly bright, active galaxies.
What's most important for this discussion is the"very distant" part of that conclusion.
Because light takes time to travel from one place to another, we don't see stars and galaxies as they are now, but as they were thousands, millions or billions of years ago. That means that looking deeper into the universe is also looking deeper into the past. We see a lot of quasars in the distant cosmos, which means these objects were very common billions of years ago. But there are hardly any quasars in our local, up-to-date neighborhood. And they’re common enough in the far-away (that is, young) universe that we should see a lot more in our vicinity.
The simple conclusion: The universe was different in its past than it is today.
#3: It's getting bigger
We live in an expanding universe. On average, galaxies are getting farther away from all other galaxies. Sure, some small local collisions happen from leftover gravitational interactions, like how the Milky Way is going to collide with Andromeda in a few billion years. But at large scales, this simple, expansionary relationship holds true. This is what astronomer Edwin Hubble discovered in the early 20th century, soon after finding that "galaxies" were actually a thing.
In an expanding universe, the rules are simple. Every galaxy is receding from (almost) every other galaxy. Light from distant galaxies will get redshifted — the wavelengths of light they're releasing will get longer, and thus redder, from the perspective of other galaxies. You might be tempted to think that this is due to the motion of individual galaxies speeding around the universe, but the math doesn’t add up.
The amount of redshift for a specific galaxy is related to how far away it is. Closer galaxies will get a certain amount of redshifting. A galaxy twice as far away will get twice that redshift. Four times the distance? That's right, four times the redshift. To explain this with just galaxies zipping around, there has to be a really odd conspiracy where all the galactic citizens of the universe agree to move in this very specific pattern.
Instead, there's a far simpler explanation: The motion of galaxies is due to the stretching of space between those galaxies.
We live in a dynamic, evolving universe. It was smaller in the past and will be bigger in the future.
#4: The relic radiation
Let's play a game. Assume the universe was smaller in the past. That means it would have been both denser and hotter, right? Right — all the content of the cosmos would've been bundled up in a smaller space, and higher densities mean higher temperatures.
At some point, when the universe was, say, a million times smaller than it is now, everything would have been so smashed together that it would be a plasma. In that state, electrons would be unbound from their nuclear hosts and free to swim, all of that matter bathed in intense, high-energy radiation.
But as that infant universe expanded, it would've cooled to a point where, suddenly, electrons could settle comfortably around nuclei, making the first complete atoms of hydrogen and helium. At that moment, the crazy-intense radiation would roam unhindered through the newly thin and transparent universe. And as that universe expanded, light that started out literally white-hot would've cooled, cooled, cooled to a bare few degrees above absolute zero, putting the wavelengths firmly in the microwave range.
#5: It's elemental
Push the clock back even further than the formation of the cosmic microwave background, and at some point, things are so intense, so crazy that not even protons and neutrons exist. It's just a soup of their fundamental parts, the quarks and gluons. But again, as the universe expanded and cooled from the frenetic first few minutes of its existence, the lightest nuclei, like hydrogen and helium, congealed and formed.
We have a pretty decent handle on nuclear physics nowadays, and we can use that knowledge to predict the relative amount of the lightest elements in our universe. The prediction: That congealing soup should have spawned roughly three-fourths hydrogen, one-fourth helium and a smattering of "other."
The challenge then goes to the astronomers, and what do they find? A universe composed of, roughly, three-fourths hydrogen, one-fourth helium and a smaller percentage of "other." Bingo.
There's more evidence, too, of course. But this is just the starting point for our modern Big Bang picture of the cosmos. Multiple independent lines of evidence all point to the same conclusion: Our universe is around 13.8 billion years old, and at one time, it was the size of a peach and had a temperature of over a trillion degrees.
Sound is broked.
I knew I shouldn’t have stopped giving to PBS thirty years ago.
I’m sure it is wonderful, but I’m also quite sure it won’t explain, but rather posit.
I can do that too.
Sorry about the video. Should have checked it first. I had remembered seeing the clip in an old documentary titled Creation of the Universe, hosted by Timothy Ferris.
I found this transcript of the segment...
“The universe may have begun in a state of perfect symmetry. . . .
Perfect symmetry may be beautiful, but it is sterile; perfectly symmetrical space means nothingness. . . .
It may even be that we owe the very origin of our universe to the imperfection of the breaking of the absolute symmetry of absolute emptiness. There is even a theory to this effect.
It’s called vacuum genesis and it suggests that the universe began as a single particle arising from an absolute vacuum.
Curious as it may seem, this idea violates none of the known laws of physics. We have seen how virtual particles come into existence all the time from a vacuum and then fall back into non-existence. . . .
It’s just possible that there might have been absolutely nothing out of which came a particle so potent that it could blossom into the entire universe. It is not very likely, but then it only had to happen once. Out of nothingness could have come the spark of genesis.”
Timothy Ferris
The Creation of the Universe, 1985
http://www.vacuumgenesis.com/definition.html
Very pretty.
Glad it works for you.
On the other hand the whole thing could of popped out in a fart from Beezlebub.
It would only have had to happen once!
For what it’s worth...
‘A Universe From Nothing’ by Lawrence Krauss, AAI 2009
Richard Dawkins Foundation for Reason & Science
1,979,617 views
https://m.youtube.com/watch?v=7ImvlS8PLIo
One universe to another: "Man, I haven't see you in 14 billion years. You sure did blow up! I told you to lay off the carbs."
Regarding that lecture video I just posted a link to, if you can tolerate the typical liberal-academic arrogance and elitism, you may gain some insight into the current ideas of what the ‘experts’ think may have preceded the big bang.
...I would suggest taking a pass on that lecture video I linked to. I tried to watch it but couldn’t tolerate the liberal academic a-holes.
Thanks again for offering your thoughts!
This video is a lot better...
It’s a different person, despite the identical title.
“Something From Nothing”: Virtual Particles and Gravity
https://m.youtube.com/watch?v=UzLDkMfR_60
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.