[Zer0 (OP)]

Why is Space considered as a Void/Empty/Vacuum?

If I observe a woman walking down the road n can't help but appreciate her wonderful natural beautiful curves, 👯 n the next moment think the woman is a nonexistent entity how could I then with a scientific temperament be foolishly ignorant to praise her natural beauty. 🙉

In the same manner we know Light bends, but Gravity doesn't bend Light right? 🎐

Gravity creates a shallow dent impression in the fabric of SpaceTime right? 🌊

When Light passes through the SpaceTime Medium which is curved, Light follows the curved path right? 🌉

Now if Space is void vacuumed n empty, how can it possibly inherit the quality to have a curvature? 😵

[Kryptid]

It depends on how you define "empty". You could consider the space where a field of some kind exists (gravity, electromagnetism, or something else) to not be empty. Even in a parcel of space where there is no matter or fields generated by that matter, there are still quantum vacuum fluctuations present.

[evan_au]

Now if Space is void vacuumed n empty, how can it possibly inherit the quality to have a curvature? 😵

Imagine an isolated neutron star, perhaps 10km across, with the mass of the Sun.

It has a dense atmosphere, perhaps a few inches thick, with a very good vacuum beyond that. It also has very deep gravitational well that is strong even millions of miles away.

So a photon passing perhaps 1 mile from the neutron star is passing through a very good vacuum, and yet it's path is still bent by the strong gravitational field which exists in that vacuum.

An even more extreme case exists with black holes - the path of passing light can be bent so severely that the light orbits 2 or 3 times around the black hole before continuing onwards to reach us!

[Bill S]

Could be the tendency to think in terms of physical curvature is part of the problem.   Spacetime is not curved within some higher dimensional medium.  What we think of as curvature (for convenience, and because the maths works) is a situation which makes one direction special, as compared to other directions.  Viewed that way, the question of emptiness, or otherwise, is not a problem.

An even more extreme case exists with black holes - the path of passing light can be bent so severely that the light orbits 2 or 3 times around the black hole before continuing onwards to reach us!

If gravity is strong enough to cause light to go into orbit, what might change to allow it to escape?

[jeffreyH]

If gravity is strong enough to cause light to go into orbit, what might change to allow it to escape?

Possibly quantum fluctuations.

[mrsmith2211]

I think vacuum exists as a matter of convenience, rather than a practical application, take a neutrino as an example, take 2 they are small.

[evan_au]

If gravity is strong enough to cause light to go into orbit, what might change to allow it to escape?

A photon in a closed circular orbit will not escape.
But a photon well outside this distance might have its path deflected by (say) 30 degrees.
In between, there are paths that will deflect the photon by 180 degrees, 360 degrees or 720 degrees.

take a neutrino as an example, take 2 they are small.

There are many meanings of "small".
- One measure the nuclear cross-section: the probability that it will interact with a nucleus. And this is small, for a neutrino.
- Another measure is the wavelength. For a particle like the neutrino which has mass, the wavelength varies with energy/velocity (high energy = shorter wavelengths)

We have not yet been able to measure the rest mass of a neutrino, but guesses suggest that the wavelength could be anywhere from centimeters to meters.

I think vacuum exists as a matter of convenience, rather than a practical application, take a neutrino as an example, take 2 they are small.

How does the size of a neutrino affect the vacuousness of space?

[Zer0 (OP)]

If gravity is strong enough to cause light to go into orbit, what might change to allow it to escape?

Possibly quantum fluctuations.

Are you folks hinting at the galactic streams or beams of excessive energy coming out of black holes?
Theories on black holes are still under formation, one such states black holes have tremendous gravity, not allowing light to escape hence they are black n dark.
Now a beam of light would have to break the light speed barrier in order to reach escape velocity or possible quantum fluctuations.
I just came across another possible explanation according to it the beam of light originates in the outermost part of the blackhole rather than originating from inside of it, Please have a look.

https://www.jpl.nasa.gov/news/news.php?feature=4753


Screenshot_20171023-161030.png (399.63 kB . 600x1024 - viewed 5629 times)

[Bill S]

Are you folks hinting at the galactic streams or beams of excessive energy coming out of black holes?

I was visualising a beam of light passing a BH and being deflected such that it went into orbit.  I think that's quite different from the jets that appear to escape from BHs. 

[Zer0 (OP)]

Are you folks hinting at the galactic streams or beams of excessive energy coming out of black holes?

I was visualising a beam of light passing a BH and being deflected such that it went into orbit.  I think that's quite different from the jets that appear to escape from BHs.

Oh Yes I got it, Sorry Bill[edited] I somehow missed out on reading evan_au's statement.

Quote from: evan_au
An even more extreme case exists with black holes - the path of passing light can be bent so severely that the light orbits 2 or 3 times around the black hole before continuing onwards to reach us!

Bill S:
If gravity is strong enough to cause light to go into orbit, what might change to allow it to escape?

[Bill S]

Returning to the OP:

Christophe Galfard (The Universe in Your Hand) says:

“To appear, particles have to borrow some energy from the quantum fields,  And since those fields fill in every place in space and time.  Particles can literally appear anywhere, and anytime.  That is the reason why there is no such thing as true emptiness, anywhere in the universe.”

Initially, I found this book off-putting, but much later, I decided to give it another go.  I’m glad I did. I would recommend it to absolute beginners.

[evan_au]

I just came across another possible explanation according to it the beam of light originates in the outermost part of the blackhole rather than originating from inside of it

Yes, that is the conventional explanation - light comes from the accretion disk around a black hole, which is outside the event horizon.
See: https://en.wikipedia.org/wiki/Accretion_disk

There is another potential source of light from the vicinity of the event horizon, predicted by Stephen Hawking. But the amount of this light is extremely small - effectively undetectable for a stellar-mass black hole. All radiation we detect comes from the accretion disk.
See: https://en.wikipedia.org/wiki/Hawking_radiation

[Zer0 (OP)]

I read through the Basics.
Newtonian Theory of flat earth, longitudinal lines parallel on a flat 2d map.
Einsteinian Theory of round earth, longitudinal lines remain parallel even though they originate from the same point and end at the same point.

I realized my mistake, I was literally visualizing space as a tablecloth n the heavy Sun kept on top of it hence the weight creating a shallow dent on the surface of the cloth.
I was wrong.
Now I'm imagining the cloth made up of Space & Time entwined n entangled hence 4d.
The Curvature was not in Space, it was in my head. 😇
Thank You all for your clarifications n comments. 😀

[Zer0 (OP)]

Now returning back on the Base Question, I will rephrase it in order to understand it deeper.

"On February 11, 2016, the LIGO Scientific Collaboration and Virgo Collaboration published a paper about the detection of gravitational waves, from a signal detected at 09.51 UTC on 14 September 2015 of two ~30 solar mass black holes merging about 1.3 billion light-years from Earth."

Based on the above statement☝ quote ⬆ :
Would it be wrong to conclude that from the 2 merging BHs till the Earth a total distance of 1.3bly there is no void or emptiness in a straight line as gravitational waves originated there n reached here?

I Agree there could be a Vacuum, but Not absolute Void or Nothingness as the space would be stuffed with different variating gravity fields, electro magnetic fields n quantum flux.
Makes Sense Right?

[jeffreyH]

Wheel a shopping cart down a smooth tarmac road. Now wheel it down a cobbled street. You'll get the picture. Think of your cobbled street as the vacuum.

[Zer0 (OP)]

Just finished reading about WMAP and CMB(R) which cleared a lot of concepts.
Also...
"In quantum field theory, the quantum vacuum state (also called the quantum vacuum or vacuum state) is the quantum state with the lowest possible energy. Generally, it contains no physical particles. Zero-point field is sometimes used as a synonym for the vacuum state of an individual quantized field."
So the base question stands answered.

Subject:
Re:  Why is Space considered as a Void/Empty/Vacuum?
It is an outdated consideration, keeping Quantum Theory in place one can scientifically conclude there is absolutely no void or vacuum or emptiness in space.

Once again, Thank you all for your views n clarifications n explanations.
🙏

[Bill S]

one can scientifically conclude there is absolutely no void or vacuum or emptiness in space.

I would not argue with that, but it is worth remembering that linguistic usage is such that words like “void” and “vacuum” can be, and are, used by scientists in specific ways, such that they don’t always imply “emptiness”. 

Just think of the ways in which “nothing” is used. 

One of my favourite quotes is from Lawrence Krauss:  “By nothing, I do not mean nothing…..”

[yor_on]

It's weird, isn't it?

Scaling the universe down you end in probabilities and uncertainty. Scaling it up you end with what we observe macroscopically. If it's a 'field' then 'change' is what makes it tick. So with 'change' we find lights propagation 'bend' to mass/gravity/'energy'. From the view point of that 'field' it's just the way it change in time, no motion involved, well, the way I look at it.
=

That doesn't need to define the vacuum as being 'something' though, it's more of a macroscopic geometry to me. What defines 'change' are 'interactions', not the vacuum per se.

[Bill S]

What defines 'change' are 'interactions', not the vacuum per se.

Are these interactions the result of things interacting with the vacuum?

[yor_on]

Within? The vacuum. If that is what you're thinking of, then

As a geometry, yes
As for 'being' a vacuum?

Nope, not classically. If you want it as a 'field' extended into a 'universe then, maybe? We're at an inside, and there is no looking out.