# Does space bend In a pure vacuum ?

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#### river

So far I have not found any proof that space bends in a pure vacuum. ( pure vacuum is defined as devoid of any quantum matter and/or smaller ).

I don't think that space " bends " at all ; it is the matter IN space that forms any geometry between the macroscopic forms such as the Sun and planet(s) .

Are you talking about curved space?

I don't think that space " bends " at all
And you would be correct. Spacetime has a curvature.

In answer to your OP:
If you were to isolate a volume of space between here and the Moon, say, one cubic metre, and ensure that there were no atoms in there, you could indeed measure the space time curvature within it. It would be as simple as placing a particle within the volume and watching that particle fall toward Earth under the influence of gravity. In an Einsteinian universe, gravity is the curvature of spacetime.

And you would be correct. Spacetime has a curvature.

In answer to your OP:
If you were to isolate a volume of space between here and the Moon, say, one cubic metre, and ensure that there were no atoms in there, you could indeed measure the space time curvature within it. It would be as simple as placing a particle within the volume and watching that particle fall toward Earth under the influence of gravity. In an Einsteinian universe, gravity is the curvature of spacetime.

Not good enough , want the whole of the volume of space between Macro-objects , suns and planetary , to be devoid , of anything atomic and further quantum and smaller , energy and/or quantum state .

Inotherwords Dave , the volume of space between Earth and Moon , three dimensionaly, has NO energy nor matter form .

Not good enough , want the whole of the volume of space between Macro-objects , suns and planetary , to be devoid , of anything atomic and further quantum and smaller , energy and/or quantum state .
Well, you won't get that in our universe. Every cubic millimetre of space is pervaded with electromagnetic radiation. Even if it's dark as heck, it's still irradiated by the CMBR.

river said:
Not good enough , want the whole of the volume of space between Macro-objects , suns and planetary , to be devoid , of anything atomic and further quantum and smaller , energy and/or quantum state .

Well, you won't get that in our universe. Every cubic millimetre of space is pervaded with electromagnetic radiation. Even if it's dark as heck, it's still irradiated by the CMBR.

And physical matter , from the macroscopic ; to the microscopic . Not just electromagnetic radiation .

And the reason that any electromagnetic radiation exists is because of physical matter. Without physical matter , electromagnetic radiation would not exist .

Moving on , back on the OP topic ; REMOVING all forms of energy and matter , no matter the scale of size , macro and micro in a defined space , this defined space is the distance to the moon and back , three dimensionally . 360° degrees .

A Pure vacuum .

In this pure vacuum , Does space bend , curve ? Could it ?

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According to the general theory of relativity, spacetime is flat in the absence of any mass or energy.

You've heard the saying, haven't you? "Matter tells spacetime how to curve..."

"Matter tells spacetime how to curve..."
I see that is ** the saying .But should it really be "Mass tells spacetime how to curve..." since not all matter has mass ....or does it? (can massless particles also curve spacetime if they have energy?)

Also can we say that it is not spacetime that curves (except when viewed in a model) but the spacetime distances that lengthen or shorten in proportion to the relationship between measured space and measured time?

**not the "wrong" one running through my head though.It is the one with "mass" that I assumed it was.

According to the general theory of relativity, spacetime is flat in the absence of any mass or energy.

You've heard the saying, haven't you? "Matter tells spacetime how to curve..."
Well, depends on what you mean. Or what River means.

Even if there was a complete absence of matter between Earth and Moon, the spacetime there would still have a curvature because of the nearby masses.

And the reason that any electromagnetic radiation exists is because of physical matter. Without physical matter , electromagnetic radiation would not exist .
Since there was a epoch of the universe where it was only electromagnetic radiation, this is obviously not true.

Since there was a epoch of the universe where it was only electromagnetic y not true.
Did one then have gravity (ie spacetime, apparently) with just em radiation ?

Did one then have gravity (ie spacetime, apparently) with just em radiation ?
Presumably, yes. Gravity broke away from the symmetry first, so there would have been a period where gravity existed but particles had not yet sublimated from energy.

Presumably, yes. Gravity broke away from the symmetry first, so there would have been a period where gravity existed but particles had not yet sublimated from energy
So the em field started almost symmetrical and was eased apart by gravity along lines of asymmetricality?

I am not sure if "sublimated from energy" sounds right.

Energy is a property of matter,I have heard and not a thing per se.

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Enegy is a property of matter,I have heard and not a thing per se.
Please don't hijack the thread.

So the em field started almost symmetrical and was eased apart by gravity along lines of asymmetricality?

I am not sure if "sublimated from energy" sounds right.

Energy is a property of matter,I have heard and not a thing per se.
Sorry. You're right. That should have read EMR.

Since there was a epoch of the universe where it was only electromagnetic radiation, this is obviously not true.
False. If your assertion were true, matter-antimatter imbalance could never happen, and planets, stars, galaxies etc. could never exist. Nothing in QED allows a matter-antimatter asymmetry.
The very early universe is believed to have been dominated by a quark-gluon plasma, and an as yet unknown BSM interaction operated there to yield an eventual one baryon per ~ 10^10 photons. Leptons (mostly electrons and neutrinos) and DM make up additional portions whose estimated numerical values can easily be found with a web search.

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