How big is the universe?

[SLD]

When we look out across the cosmos, we can see as far back in time as 13.6 Billion years ago. Yet the universe has expanded greatly since then so we know those objects are now 42 billion light years away. But the problem is that we still don’t see any curvature to soacetime at that scale. We have a flatness problem. The universe must be significantly larger than 42 billion light years radius. At present we can only make educated guesses than as to how much larger the universe is than we can see.

One analogy is earth. If you are out at sea, one sees only a flat line all around you. How far you can see depends on your height of eye. The higher you go the farther you will see. However even flying in an airplane at 30,000 feet you would see no curvature. I think I recall reading you really need to get above 100,000 feet, or close to 20 miles up to see the curvature.

The earth's radius is roughly 4000 miles. So one must get .005 above the surface to detect it’s curvature. Roughly. And that’s really more of a psychological thing as I’m sure fine instruments can detect it better than humans could. Thus if we’re at the limit to see the curvature of space than the total universe would be 8400 billion light years radius. But it could be much larger still. We could be just barely above the horizon.

Thoughts?

SLD

 

[steve_bank]

I do not buy a bound3d universe.

What we see is based on our ability to detect photons which is finite. Theory is based on observation, and observation has limits. What we imagine as the BB may be an infinitesimally small event in relation to the totality of the universe. As an an logy, the volume of the Erath compared to the observable volume of the universe.

 

[SLD]

I do not buy a bound3d universe.

What we see is based on our ability to detect photons which is finite. Theory is based on observation, and observation has limits. What we imagine as the BB may be an infinitesimally small event in relation to the totality of the universe. As an an logy, the volume of the Erath compared to the observable volume of the universe.

There is a boundary to our particular physical universe that was born in the Big Bang 13.6 billion years ago. It's been expanding ever since from an atomic scale to now where the visual portion is 42 billion light years radius. But what we can see is a fraction of the overall universe.

 

[steve_bank]

I do not buy a bound3d universe.

What we see is based on our ability to detect photons which is finite. Theory is based on observation, and observation has limits. What we imagine as the BB may be an infinitesimally small event in relation to the totality of the universe. As an an logy, the volume of the Erath compared to the observable volume of the universe.

There is a boundary to our particular physical universe that was born in the Big Bang 13.6 billion years ago. It's been expanding ever since from an atomic scale to now where the visual portion is 42 billion light years radius. But what we can see is a fraction of the overall universe.

In the beginning god created the heaven and the Earth...science, philosophy, and religion converge.

There is WAG a wild ass guess and SWAG a scientific wild ass guess. SWAG is based on objevtive projection where there is no direct evidence or proof.

We have no idea what the universe looks like out at the limit of our observation.

Consider ancient Zog looking out at the ocean thinking the horizon was the end of world. The BB is a good model as far it goes, but it is hubris to imagine we humans on our infinitesimally small planet with our minuscule brains can deduce the universe.

 

[Jokodo]

I do not buy a bound3d universe.

What we see is based on our ability to detect photons which is finite. Theory is based on observation, and observation has limits. What we imagine as the BB may be an infinitesimally small event in relation to the totality of the universe. As an an logy, the volume of the Erath compared to the observable volume of the universe.

There is a boundary to our particular physical universe that was born in the Big Bang 13.6 billion years ago.

If you have evidence there is, you should be collecting your Nobel prize.

 

[Cheerful Charlie]

Some years ago, I read an article on the size of the observable Universe. Because of inflation, the universe is bigger that one would expect of a Universe being 13.5 billion years old expanding at the speed of light. Observations from Hubble et al suggested a diameter of 128 billion light years. YMMV.

 

[DBT]

I vote for an infinite/eternal multiverse.

 

[steve_bank]

I vote for an infinite/eternal multiverse.

That is what makes sense to me, but it is just speculation on my part.

 

[DBT]

It a proposition, a possibility that's better than some.

 

[steve_bank]

In the beginning all there was a hot dense soup. Suddenly a quantum flucuati0n that trigged a transformation into the universe.

I am not trying to diminish the achieving of the model and all it provides. It is that in pop science it is takes as gospel truth. It has become a creation myth.

 

[Peez]

The obvious response:

Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the drug store, but that's just peanuts to space.

- Douglas Adams

 

[Testy Calibrate]

It's turtles all the way down

 

[SLD]

I vote for an infinite/eternal multiverse.

I do too, but that’s a different debate.

SLD

 

[SLD]

I do not buy a bound3d universe.

What we see is based on our ability to detect photons which is finite. Theory is based on observation, and observation has limits. What we imagine as the BB may be an infinitesimally small event in relation to the totality of the universe. As an an logy, the volume of the Erath compared to the observable volume of the universe.

There is a boundary to our particular physical universe that was born in the Big Bang 13.6 billion years ago.

If you have evidence there is, you should be collecting your Nobel prize.

According to this article the size of the universe went from atomic scale to golf ball size during inflation.

https://www.space.com/52-the-expanding-universe-from-the-big-bang-to-today.html

Other sizes after inflation I’ve read include grapefruit to solar system size. Regardless, it had a size and has been expanding ever since. I don’t understand how it would not be considered to still have a size 13.6 billion years later. Mind you I’m not talking about the multiverse, which is a scientific conjecture concerning other universes, some with different laws of physics. Our universe may just be a bubble on an infinite sea of other universes, but it is that bubble whose size I’m interested in determining.

SLD

 

[Jokodo]

If you have evidence there is, you should be collecting your Nobel prize.

According to this article the size of the universe went from atomic scale to golf ball size during inflation.

https://www.space.com/52-the-expanding-universe-from-the-big-bang-to-today.html

Other sizes after inflation I’ve read include grapefruit to solar system size. Regardless, it had a size and has been expanding ever since. I don’t understand how it would not be considered to still have a size 13.6 billion years later. Mind you I’m not talking about the multiverse, which is a scientific conjecture concerning other universes, some with different laws of physics. Our universe may just be a bubble on an infinite sea of other universes, but it is that bubble whose size I’m interested in determining.

SLD

Which part of that says that it has a boundary or even a finite size?

Your link even says that for all imaginable scenarios, the universe is either expected to be finite but without bounds, or infinite (under the header "Shape").

 

[SLD]

If you have evidence there is, you should be collecting your Nobel prize.

According to this article the size of the universe went from atomic scale to golf ball size during inflation.

https://www.space.com/52-the-expanding-universe-from-the-big-bang-to-today.html

Other sizes after inflation I’ve read include grapefruit to solar system size. Regardless, it had a size and has been expanding ever since. I don’t understand how it would not be considered to still have a size 13.6 billion years later. Mind you I’m not talking about the multiverse, which is a scientific conjecture concerning other universes, some with different laws of physics. Our universe may just be a bubble on an infinite sea of other universes, but it is that bubble whose size I’m interested in determining.

SLD

Which part of that says that it has a boundary or even a finite size?

Your link even says that for all imaginable scenarios, the universe is either expected to be finite but without bounds, or infinite (under the header "Shape").

Either way the question still stands. There’s an end to matter in our universe. There’s only a finite amount of it. And it occupies therefore only a finite amount of space. At one point that size was golf ball size. What is it now?

SLD

 

[Jokodo]

Which part of that says that it has a boundary or even a finite size?

Your link even says that for all imaginable scenarios, the universe is either expected to be finite but without bounds, or infinite (under the header "Shape").

Either way the question still stands. There’s an end to matter in our universe.

Says who?

There’s only a finite amount of it.

Based on what evidence?

And it occupies therefore only a finite amount of space. At one point that size was golf ball size. What is it now?

Arguably they meant the visible universe was the size of a golf ball. Not knowing the size of the universe in toto today (and the article makes it quite clear we don't), it is logically impossible to determine its size at a particular point in its past. Your own link is very clear on that.

 

[steve_bank]

If I hold up a meter stick against the night sky I'd say it is bigger than a meter across. .

 

[DBT]

I vote for an infinite/eternal multiverse.

I do too, but that’s a different debate.

SLD

Well, if what we call the universe is actually a part of a far larger system, a multiverse...our universe is not a universe at all. It is the multiverse that is the universe and our little part of it is merely an infinitesimal bubble.

 

[steve_bank]

Does the BB actually yield a finite size?

At the time of the event there was no center point. Observation says galaxies are moving awy from each other not diverging from a central point.

No matter what observational point you pick the belie is the observation will be the same. Things are spreading out from each other.