Lets say the universe is expanding

Lets say the universe is expanding,
what exactly is it, that expands?
Is one liter of water having a different volume each time it's measured, due to expansion? Or is matter itself not changing, but the vacuum gets bigger? Which on the other hand would cause a liter of water weigh less, each time measured, no?

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Uh, no, what is happening is the objects in the universe are constantly travelling outwards, hence expanding the bound of the universe. It has nothing to do with the expansion of matter, brainlet.

that's been my second question, no?
so, as mass doesn't depend only on the gravitation of the nearest object but on the total gravitational force, and other object moves further away of my liter of water, doesn't that make the water weigh less?

no, because you need an object of reference for any effect to be observed. The weight of a liter of water is not effected when a bird flies past it, nor when the moon is further away from it. It is weighed in relation to earth as a body - the only thing that would change the 'weight' of the water is if the mass of the earth changed.

Any measure of one light-year grows about 2cm each second.
This is slow enough that our galaxy gets pulled back together by gravity.

>so, as mass doesn't depend only on the gravitation of the nearest object but on the total gravitational force
Holy shit.

ok this becomes clear when looking at the effect of gravitation as a perception, rather than a fixed thing. it just came to me that water doesn't have any weight in space...could have thought about that.


mirin my combinatorics? starting undergrad in Mathematics tomorrow to achieve mastery.

>mass
>depend on the gravitation

space itself expands
if you think of the universe as of a sheet of paper, the sheet itself is expanding, not the things drawn on it

>not the things drawn on it
not quite true, they would expand too, but gravity and EM overcome the expansion

youtu.be/zO2vfYNaIbk?t=9m50s

Universal expansion is just that, a universal phenomenon. On smaller scales (anything smaller than a small galaxy cluster, and that's big) gravity prevails over expansion, so individual galaxies do not expand, but slide through the expanding universe to keep their overall shape. This continues all the way down to where electromagnetism starts to challenge gravity as the dominant force.

I unironically hate high schoolers.

The mass number would in fact depend on the gravitation force

The force itself depends on mass

Yes user, your love for little boys is common knowledge.

>the mass number
what do you mean?
as in the atomic mass or the reading of a scale, please clarify

Scale, degree, intensity, amount

de·gree
dəˈɡrē
noun
1.
the amount, level, or extent to which something happens or is present.

synonyms: level, standard, grade, mark; amount, extent, measure; magnitude, intensity, strength; proportion, ratio
"to a high degree"

I'll have what he is having.

the space between every pont expands the same amount every time all the time at the same time

...

then doesn't that mean the points at the edge move farther and faster than the ones near the center of the expansion point?
no other way to keep the distance between all points the same, is there?

yes
the objects at the edge of our observable universe, 46 bn ly away, are receding from us at 3x the speed of light

Elitism is why I can't stand this board. No higher intellectual does this shit.

no one gives a shit of your f-f-feelings user, but thanks for the bump

No idea op but check these dubs

>the mass number would in fact depend on the gravitation force