The Big Bang

[Paradoxum]

I came across a video recently that made me question my understanding of the Big Bang. I thought it meant that the whole universe was once a singularity, comparable to a black hole singularity. ie: The universe was a dot (or close to it). But the video I watched suggested that space merely contracted, which means that the universe was just really dense and hot, but not a singularity.

Is one of these more true, or is it simply unknown?

 

[Strathos]

According to my (layman's) understanding, it was both. It was a singularity, but that singularity was all of space and time, so nothing (in the universe) existed outside of it.

 

[EnemyOfReason]

The issue truthfully is not whether or not it is a singularity. It really goes down to semantics and how one views the word singularity. I have heard people rephrase it as a singularity in causality.

 

[Bill Shadowcat]

the universe was just really dense and hot,

I wonder what made it so hot.

 

[Strathos]

It would be the pressure from all of the matter and energy concentrated in one spot.

 

[Bill Shadowcat]

But where'd all the matter and energy come from?

 

[Gottservant]

It's all relative.

If you make something out of nothing, you are either anywhere or somewhere, but you can't be both.

So decide first where you are, in relation to it.

 

[GrowingSmaller]

Its unknown afaict from reaading. There are physical theories which entail an big bang, and others which dont like big bounce theory.

 

[Paradoxum]

Thanks for the replies.

I guess it depends on your view of the universe? If you think it is infinite, then it can't turn into a singularity like with a black hole, but if it isn't finite then it could?

I guess is the laws if physics seem to break down anyway, it doesn't matter which it is?

I'm just trying to understand what it is I should picture, even though the picture will be wrong.

It's all relative.

If you make something out of nothing, you are either anywhere or somewhere, but you can't be both.

So decide first where you are, in relation to it.

I don't know what you mean.

 

[Heissonear]

The issue truthfully is not whether or not it is a singularity. It really goes down to semantics and how one views the word singularity. I have heard people rephrase it as a singularity in causality.

If the physical realm was once a concentrated singularity then why is the universe some 154 light years in expansion but 15.4 byo?

Sitting on the face of the earth, using one's brain to fathom existence, and completely unaware of Him in their midst, acting like He's not around.

"The issue"

You miss it big time, friend.

 

[EnemyOfReason]

If the physical realm was once a concentrated singularity then why is the universe some 154 light years in expansion but 15.4 byo?

Sitting on the face of the earth, using one's brain to fathom existence, and completely unaware of Him in their midst, acting like He's not around.

"The issue"

You miss it big time, friend.

What are you babbling about? The Universe is over 40 billion Ly in expansion not 154 million.

Are you seriously trying to impress me with your lack of scientific understanding?

 

[bhsmte]

What are you babbling about? The Universe is over 40 billion Ly in expansion not 154 million.

Are you seriously trying to impress me with your lack of scientific understanding?

He often does that!

 

[Michael]

Thanks for the replies.

I guess it depends on your view of the universe? If you think it is infinite, then it can't turn into a singularity like with a black hole, but if it isn't finite then it could?

I guess is the laws if physics seem to break down anyway, it doesn't matter which it is?

I'm just trying to understand what it is I should picture, even though the picture will be wrong.

"Generally speaking", most astronomers that I talk with tend to "hedge their bets" on the actual "size" of the "clump" prior to expansion. They tend to avoid the concept of 'singularity', mainly because that is where the laws of physics tend to "break down". They tend to use terms like 'near singularity' rather than claiming that it's a singularity.

Keep in mind that I don't personally buy into any of their nonsense, but I can tell you that most of them are uncomfortable about describing the "clump" as a "singularity". Some do that of course, but usually only on websites. In actual online debates they tend to 'hedge their bets'.

 

[Davian]

I came across a video recently that made me question my understanding of the Big Bang. I thought it meant that the whole universe was once a singularity, comparable to a black hole singularity. ie: The universe was a dot (or close to it). But the video I watched suggested that space merely contracted, which means that the universe was just really dense and hot, but not a singularity.

Is one of these more true, or is it simply unknown?

The "singularity" is comparable in that it describes a point in space-time at which the space-time curvature becomes infinite (Hawkings words), but different as it is happening in reverse (expanding) to that of a black hole.

The Beginning of Time - Stephen Hawking

 

[Davian]

"Generally speaking", most astronomers that I talk with tend to "hedge their bets" on the actual "size" of the "clump" prior to expansion. They tend to avoid the concept of 'singularity', mainly because that is where the laws of physics tend to "break down". They tend to use terms like 'near singularity' rather than claiming that it's a singularity.

Keep in mind that I don't personally buy into any of their nonsense, but I can tell you that most of them are uncomfortable about describing the "clump" as a "singularity". Some do that of course, but usually only on websites. In actual online debates they tend to 'hedge their bets'.

Do try to keep *your* nonsense to your own threads. Thanks.

 

[Davian]

Thanks for the replies.

I guess it depends on your view of the universe? If you think it is infinite, then it can't turn into a singularity like with a black hole, but if it isn't finite then it could?

I don't think that an infinite universe is compatible with the big bang theory, as an infinite amount of mass accelerated to the speed of light at the initial expansion would be in violation of the laws of physics that should have applied at that time. I have lost my reference for this, but I think it was discussed on the Astronomy Cast podcast.

I guess is the laws if physics seem to break down anyway, it doesn't matter which it is?

Maybe they don't "break down". Maybe they are "different". Does it matter me? Only out of curiosity. You?

I'm just trying to understand what it is I should picture, even though the picture will be wrong.

There will always be shortcomings to any model. What exactly are you trying to picture?

Ep. 295: The Observable Universe | Astronomy Cast

 

[Michael]

Do try to keep *your* nonsense to your own threads. Thanks.

You got it chief. This thread is about *your* nonsense, not mine.

 

[Gottservant]

Thanks for the replies.

[...]

I don't know what you mean.

I mean you are in the world, right?

So you have a choice as to how to interpret the beginning.

Science tells us that the interpretation we adopt affects the type of thing we see.

The first step is to work out what kind of interpretation you want.

 

[bhsmte]

I mean you are in the world, right?

So you have a choice as to how to interpret the beginning.

Science tells us that the interpretation we adopt affects the type of thing we see.

The first step is to work out what kind of interpretation you want.

Psychology tells us many will see the interpretation we want to see. If someone has a deeply held belief, and science comes along with verifiable evidence to refute that belief, some will accept the evidence, while others will dig in, and have a long term bout of cognitive dissonance to hold onto their belief.

Science will tell us about the world, through the scientific method. One can accept the evidence that science reveals or they can reject the same. It all depends on what psychological needs one may have. Some want to understand the truth and some want to hold onto their belief, whatever floats your boat.

 

[essentialsaltes]

I came across a video recently that made me question my understanding of the Big Bang. I thought it meant that the whole universe was once a singularity, comparable to a black hole singularity. ie: The universe was a dot (or close to it). But the video I watched suggested that space merely contracted, which means that the universe was just really dense and hot, but not a singularity.

Is one of these more true, or is it simply unknown?

Singularity doesn't necessarily mean 'compressed into a point'. A singularity is more like 'dividing by zero'. Which isn't allowed, of course.

As we run the movie of the universe backwards, the density of matter increases.

As far as we can tell, there is no way to avoid this.

So going backwards, the universe becomes denser and denser until it approaches a singularity, where the density would be infinite, everywhere.

Now, to be able to run the movie backwards, we have to know what the laws of physics are. We have every reason to believe that when matter becomes very very very dense, new laws of physics will be important, and we don't (yet) know what they are.

So if you naively continue to use the Big Bang theory all the way back, you run into a singularity. But that's not necessarily what happened, since the Big Bang theory is incomplete and is not justified under those really extreme conditions. The Big Bang theory only becomes relevant a micromininano-second after the (possible) singularity. But it's possible (maybe even likely) that the new physics that takes over right at the beginning will avoid a singularity.