Why Don't Objects Fall in Space?

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Discussion Overview

The discussion revolves around the question of why objects, such as stars and the Sun, do not fall in space. Participants explore concepts related to gravity, motion, and the nature of space, questioning the existence of a support structure that prevents celestial bodies from falling. The scope includes theoretical reasoning and conceptual clarification regarding gravitational forces and the dynamics of celestial motion.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants propose that space might have a buoyancy or support structure that prevents objects from falling, questioning what holds the Sun and other stars in place.
  • Others argue that gravity is the primary force at play, suggesting that celestial bodies are in motion relative to one another and that their apparent stability is due to gravitational interactions.
  • A few participants highlight the idea that there is no absolute direction in space, emphasizing that motion is relative to the observer's frame of reference.
  • Some contributions mention the concept of space-time as a potential scaffolding, with gravity causing masses to attract each other, while also noting the effects of dark energy and redshift indicating that masses are moving apart.
  • There is discussion about the velocities of the Sun and other stars, with conflicting claims about their speeds and the implications of these speeds on gravitational interactions.
  • One participant references historical concepts like luminiferous aether to illustrate how scientific understanding has evolved regarding the medium in which celestial bodies exist.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the nature of motion and stability in space. There is no consensus on whether a support structure exists or how gravity operates in this context, leading to an unresolved discussion.

Contextual Notes

Participants express uncertainty regarding the exact velocities of celestial bodies and the implications of these speeds on gravitational dynamics. There are also references to historical theories that have been challenged by modern physics, indicating a complex interplay of ideas.

funniew
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Does space have some kind of buoyancy that prevents stuff from falling down? for instance, why doesn't the Sun fall downward eternally? Like, it is clear why the moon doesn't fall out of the sky but what is holding the Sun up in space? If you say the galaxy what is holding it up? what is the support structure for this stuff ... dark matter? Else it seems everything is just floating in space. is the entire universe everywhere filled with this support structure to prevent everything from falling?

Or is everything falling in the same frame of reference and it appears to be static? what happens if the support structure fails or becomes too diluted due to expansion?
 
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In what direction should it be falling?
 
Things only "fall" the way you're talking about because of gravity. Don't think of a model of the solar system as little balls you have to hold up, because then you'll make the mistake of implicitly thinking there is gravity you hold them up against. Presumably, there is a fairly even distribution of matter in space meaning the solar system is being attracted in many different directions, and this could balance out to hold it in place.
 
Why should it "fall"? Where would it fall to? Things fall when you drop them due to gravity. These aren't small objects near the surface of the Earth, they're massive objects in space.

Though, everything is moving outwards from a point of origin- as proven by red shift. Gravitational pull does attract the objects to one another, though it is very weak.
 
Ok, but I am not referring to gravity. There has to be some kind of scaffolding to hold the stars in position. Just seems weird that they are just sitting out there. what happened to their momentum maybe they should be falling in that direction.
 
funniew said:
Ok, but I am not referring to gravity. There has to be some kind of scaffolding to hold the stars in position. Just seems weird that they are just sitting out there. what happened to their momentum maybe they should be falling in that direction.

Yes, you are. You're used to living with gravity- and a lot of it, constantly. They aren't just sitting out there- they are moving apart from a central point. But they are certainly not "falling" as you suggested.
 
funniew said:
Ok, but I am not referring to gravity. There has to be some kind of scaffolding to hold the stars in position. Just seems weird that they are just sitting out there. what happened to their momentum maybe they should be falling in that direction.

You need to wrap your head around the idea that there is no falling in space. There is no specific up, down, left or right. Its all relative to you as an observer.

Imagine being in a geostationary orbit over the Earth's equator ( like the satellites in those positions) And your feet were in the direction of the south pole and your head towards the north pole. Now because you are used to thinking your feet and anything "below" them is down... you may say that south pole is below you.
But here I am in orbit beside you, but I am orientated the opposite way so we are looking at each other's feet ... I would argue with you that, UP is towards the south pole and down is towards the north pole. ! :)

There is no up, down, left, right ... nothing needs to be suspended.

Dave
 
... and on from that, whilst you are positioned there over the equator, rotate your body length through 360 deg, At 0deg feet to the Spole, at 90deg feet/body parallel to the equator, at 180 deg feet now towards the north pole, at 270 deg feet/ body parallel to the equator again.

NOW ... you tell me which one of those orientations is up or down etc ? ;) you cant

Dave
 
The closest thing to a scaffolding that I can think of is space-time. Gravity is an attractive force causing all masses to "fall" towards each other.
Red shifting evidence indicates that masses are actually "moving" further apart and this is attributed to dark energy.
There may very well be a scaffolding of some sort that the electroweak force doesn't interact with so it has yet to be discovered (unless you just think of it as space-time)...
 
  • #10
funniew said:
Ok, but I am not referring to gravity. There has to be some kind of scaffolding to hold the stars in position. Just seems weird that they are just sitting out there. what happened to their momentum maybe they should be falling in that direction.

The sun actually IS moving at quite a good clip around the center of the galaxy. I've heard something like 500,000 mph. But I've also heard ~52,000 mph. Maybe we don't know, but suffice to say that it's NOT standing still. It just seems liek it to us. If the sun somehow put on the brakes, then it would "fall" gravitationally towards the center of the galaxy.

Of course the center of the galaxy itself is not standing still either. However, IF something was standing still and there was no gravity acting on it, then it would indeed just chill there. Why would it move if there's no force on it?
 
  • #11
Lsos said:
The sun actually IS moving at quite a good clip around the center of the galaxy. I've heard something like 500,000 mph. But I've also heard ~52,000 mph. Maybe we don't know, but suffice to say that it's NOT standing still. It just seems liek it to us. If the sun somehow put on the brakes, then it would "fall" gravitationally towards the center of the galaxy.

Yep, it's gravity holding everything in orbit. Learning about UCM (uniform circular motion) may help you understand why the Earth doesn't fall to the centre of the solar system.

Anyway, as per SR, it's meaningless to ask whether we're standing still. From our point of view, we're standing still, obviously. From the point of view of someone sitting at the centre of the galaxy (ignoring the fact that it's pretty near impossible to survive there,) we're going pretty fast. And so on.
 
  • #12
Lsos said:
The sun actually IS moving at quite a good clip around the center of the galaxy. I've heard something like 500,000 mph. But I've also heard ~52,000 mph. Maybe we don't know, but suffice to say that it's NOT standing still. It just seems liek it to us. If the sun somehow put on the brakes, then it would "fall" gravitationally towards the center of the galaxy.
~220km/s relative to the center of the galaxy (about 9 million miles per hour), which corresponds to one orbit per ~250 million years.
Without this relative velocity, the solar system would begin to fall towards the central area.

All stars have some velocity relative to the center of the galaxy, and most of them are orbiting around it in some way.
 
  • #13
mfb said:
~220km/s relative to the center of the galaxy (about 9 million miles per hour), which corresponds to one orbit per ~250 million years.
Without this relative velocity, the solar system would begin to fall towards the central area.

I think you got a conversion factor wrong. 220 km/s is about 500,000 mph.

Here's where I was reading about the slower speed:

http://www.redorbit.com/news/space/1112533286/speed-of-the-sun-shockingly-slower-than-believed/

But they seem to have omitted some key information in the article. I'm guessing from info that I've pieced together that the solar system is actually traveling through some intersellar cloud, and 52,000 mph is the speed it's moving through this thing.
 
  • #14
It used to be thought that the stars & planets were in a medium called luminiferous aether, sort of like how a fish lives in a medium called water http://en.wikipedia.org/wiki/Luminiferous_aether
Experiments showed that luminiferous aether does not exist http://en.wikipedia.org/wiki/Michelson–Morley_experiment

funniew said:
Ok, but I am not referring to gravity. There has to be some kind of scaffolding to hold the stars in position. Just seems weird that they are just sitting out there. what happened to their momentum maybe they should be falling in that direction.
In a sense you are right, the stars & planets are rushing away from each other but nothing is "holding them up". This started at the big bang & is called the expansion of space http://en.wikipedia.org/wiki/Metric_expansion_of_space
 
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  • #15
Lsos said:
I think you got a conversion factor wrong. 220 km/s is about 500,000 mph.
Hmm, you are right, probably some typo in my WolframAlpha query.


But they seem to have omitted some key information in the article. I'm guessing from info that I've pieced together that the solar system is actually traveling through some intersellar cloud, and 52,000 mph is the speed it's moving through this thing.
That is the interstellar medium
 

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