Why do scientists think there was a big bang?

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If there is a big bang, and nobody nearby, does the big bang still make a sound?

ask a tree

-Imp

Hehe!

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I am uncomfortable with the notion that time started with the big bang. I either have a very impoverished ideation of what time is... it is not yet defined and / or discovered how and what time is. So how can people confidently say that "time started with the big bang"? It is a dimension, like a linear dimension in space, which exist whether there is matter in it there to define space, or not... time exists, whatever it is. It can't not exist, much like axes X, Y, and Z can't not exist in the three-dimensional coordiate system that can be used to describe point in space.

If someone here could please come forward and provide some sort of a descriptive explanation how time could not exist before it started with the big bang, I would be very appreciative. (While at the same time remaining critical of the notions and ideations presented.)

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In terms of narrative, I currently prefer the idea of a "big birth", where a new universe may form from the void left by the last.

I had developed two theories on what preceded the big bang. One was very romantic and went along the same line as a pulsating universe, but with some additional spice.

The one I wish to describe here, is the "bleeding" of material from one three-dimensional universe to another three-dimensional universe, both of which non-congruent 3-D universes are part of a four-D universe.

In this theory, matter is three-D; and as a plane contains infinite number of lines, and a line contains infinite number of points, a four-D space contains an infinite number of 3-D spaces. According to my theory (mostly void of math or checkable details, as you can see) a dense three-d universe had had so much matter squeezed into it, that it burst at one border with another, seemingly empty universe, ours, and some matter escaped the dense universe and found its way to the empty universe... once the matter was squeezed through, it felt depressurized, and started to expand rapidly.

[uwot]

We call it a bang, because it behaved like an explosion.

Well, there's no real analogue. Explosions as we experience them are chemical or nuclear reactions that stop once the fuel is exhausted. That more or less was the assumption behind some early interpretations, but as others have shown, it's not a very good model, and there are plenty of alternative hypotheses. I develop a simplified version of one of those (sorta Guth's inflaton field) in part two, which I'm revamping, but you can still see the old version here: https://willijbouwman.blogspot.com from page 12 of A Portrait of Reality. But...

[uwot]

From an article I was reading this morning:
https://www.quantamagazine.org/big-boun ... -20180131/

But as an origin story, inflation is lacking; it raises questions about what preceded it and where that initial, inflaton-laden speck came from.

Absolutely true. I have no idea how the 'inflaton field' came to be, or even if it's real; but I do think it is at least a useful device that helps understand stuff like quantum mechanics and relativity, without the tiresome business of learning post-graduate mathematical physics. The basic premise is simple enough: if the universe is made of any actual 'stuff', what properties would that stuff need to have to account for what we see?

In terms of narrative, I currently prefer the idea of a "big birth", where a new universe may form from the void left by the last.

Yup. Sounds plausible enough.

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We call it a bang, because it behaved like an explosion.

Well, there's no real analogue. Explosions as we experience them are chemical or nuclear reactions that stop once the fuel is exhausted. That more or less was the assumption behind some early interpretations, but as others have shown, it's not a very good model, and there are plenty of alternative hypotheses. I develop a simplified version of one of those (sorta Guth's inflaton field) in part two, which I'm revamping, but you can still see the old version here: https://willijbouwman.blogspot.com from page 12 of A Portrait of Reality. But...

To be the devil's advocate:

time is a relative measure, when considered in segments. A short time in our vernacular is a few seconds down to a few Gatyaruristen seconds, which the Big Bang lasted much longer... in fact, it is still lasting, according to some models, the names of which I am not even worthy of mentioning. But the time form then to now (roughly 15 billion years or more) is a SHORT time relatively to a time period which is, rather arbitrarily, fifteen billion times fifteen billion years.

The only way to decry the big bang as existing for a short time only, is to say the rapid expansion lasts forever. Because compared to a limited time, no matter how long the limited time lasts, an infinitely long time can't be called "short", with any stretch of imagination. And in "any stretch of imagination" I include "an infinitely long stretch of imagination".

[uwot]

Funny old world, eh?

Indeed. You are quite right that it is a question of scale, but given the supposed initial dimensions of the universe, its growth in the first few seconds I think can reasonably be called explosive. But it is an interesting point that to any 'god' that could see the entire universe (or at least our part of it), it would be like watching a balloon being blown up for nearly 14 billion years.

[uwot]

To be the devil's advocate:
time is a relative measure...

Indeed. A hour at the dentists is much longer than an hour in the pub.

...when considered in segments.

Well, segments is all time is; at least as we measure it. Seconds are divided into swings of pendulums or vibrations of atoms. It's completely arbitrary and the is no evidence that clocks are doing more than counting events and actually measuring some metaphysical stuff called time.

[uwot]

I rather like the notion that everything had its source in a point-singularity.

I also enjoy the idea that the Great Explosion is still going on, that we're ephemerals in the midst of it, thinkin' Reality is all stable and shit when -- really -- it's all in flux.

It's not nihilism, but it sure takes the edge off.

Yup. Whatever the truth is, it's a trip.

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Well, segments is all time is; at least as we measure it. Seconds are divided into swings of pendulums or vibrations of atoms. It's completely arbitrary and the is no evidence that clocks are doing more than counting events and actually measuring some metaphysical stuff called time.

Considering the above, how come some authorities deny that time existed before the big bang? There is a reference to that notion in this very thread too.

If you can, uwot, please give me a picture of what "they" mean, when they seem to say time has not lasted forever since the infinite past; and how it relates to the seemingly contradictory reality, that time is a dimension, in addition to a three-dimensional space, where the dimensions are undeniably forever lasting?

[henry quirk]

In a perfect vacuum there'd be no time cuz time is change (and the possibility of measurement) and in a perfect vacuum there's nuthin' to measure.

Introduce an energetic particle to the perfect vacuum, a decaying or changing particle, and WHAM! you have time (cuz that decaying particle can potentially be measured across the span of its changes).

So, time is (the possible perception of and the possible measuring of) changing matter.

So, even when Reality was confined to a point-singularity (the pre-universe) there was 'time' cuz sumthin' was goin' on with or inside the point-singularity, changes moving it from 'point' to 'Great Explosion', potentially measurable changes.

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time is change

I contest that. Time is not change... time is measured by change, but not defined by it. Time happens whether there is change or not.

In a perfect vacuum time happens, but you don't KNOW how much time happened; but it is knowable.

Much like in a perfect vacuum there is no measurement of distance, but you know there are distances in perfect vacuum. You just don't know how long the distance is in the vacuum.

The entire space of the universe (and not just the known universe) and time are both infinite; space, in all directions, time, going back past, and going forward into the future.

[henry quirk]

"In a perfect vacuum time happens, but you don't KNOW how much time happened; but it is knowable."

How?

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"In a perfect vacuum time happens, but you don't KNOW how much time happened; but it is knowable."

How?

Good question. If the entire universe was a perfect vacuum, then obviously no knowledge would exist.

If, however, just a little portion of this infinite expanse was not a vacuum, then you'd exploit the assumption that universal time happens everywhere at the same rate in the infinite expanse of space. Therefore anywhere where there is matter, time is possible to happen, to be known how much it happened, by the rate of change of/in matter.

Now imagine the infinite expanse of space with any amount of matter in it, and any amount of vacuum in it. The vacuum would not stop or slow down the universal time.

We have established that vacuum does not stop or slow down universal time.

Therefore if the entire space was vacuum, universal time would still happen.

It would be knowable, but there would be nobody to perceive the knowledge.

[henry quirk]

"If...just a little portion of this infinite expanse was not a vacuum, then you'd exploit the assumption that universal time happens everywhere at the same rate in the infinite expanse of space."

But that's my point exactly: the perfect vacuum is no longer a perfect vacuum when you introduce the particle, and in introducing the particle, you introduce time. In the perfect vacuum there is nuthin', nuthin', and nuthin'. And with a whole lot of nuthin' there is nuthin' to measure cuz there is no change of state. For time to exist there must be sumthin' that changes, not only as reference but as actual source (of time).

So: time is (the possible perception of and the possible measuring of) changing matter.