Albert Einstein described gravity as a curve in space that wraps around an object—such as a star or a planet.
But what is it, how does it work?
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Imagine a mattress if you put something heavy like a bowling ball in the center it creates a dent and a kind of funnel around it anything smaller will fall towards the bowling ball, gravity is this but in 4 demensions
> Albert Einstein described gravity as a curve in space that wraps around an object—such as a star or a planet.
Well, that’s what it is.
As to how it works……………… we have not a single fucking clue. It’s a complete mystery. All other forces have a particle linked to them. Gravity doesn’t appear to have any. Scientists have named any particle that may be found for gravity the graviton but there’s exactly zero evidence that they actually exist.
It’s a property of the geometry of spacetime, prompted by the presence of matter. It causes the worldlines of objects (that is, their paths through spacetime) to curve.
In other words, matter tells spacetime how to curve. That is gravity.
Veritasium has the best explanation on youtube that I have seen.
[Why Gravity is NOT a Force](https://www.youtube.com/watch?v=XRr1kaXKBsU)
Edit: formatting
gravity is the attraction of anything with mass to anything else with mass.
the space/time relativity theory is how gravity and time interact, which isn’t necessary to ‘use’ gravity in the engineering/newtonian models
as for how gravity works.. their working on that, it’s being studied by numerous quantum physics labs and it is in no way easy to explain what i think i know about what they think they know about graviton waves. https://en.wikipedia.org/wiki/Gravitational_wave
Imagine you drew a 2D plot, let’s say it’s the price of a stock over time, or a slope of a roof, or Babe Ruth’s homeruns per year. Now imagine that you could bend the paper that the plot is on, or that you had it in photoshop and used a transform command that warped it so it wasn’t a rectangular plot anymore. The plot looks different even though it’s still showing the same data. The you look up the stock price from January and it’s still the same, Babe Ruth’s runs are still the same, even though the graph looks different.
That’s what’s happening with gravity. Everything in the universe sits in space and time the same way data points do in a plot. When mass is in space, it warps spacetime (space and time are linked together). Mathematically (that is, this may not make intuitive sense right away without actually seeing/understanding the math), everything follows a straight line in spacetime. As far as we know this is a fundamental feature of the universe. We perceive this “movement along a straight line in bent spacetime” as gravity.
Of course, these words almost certainly don’t paint a good picture of what’s happening. It’s much easier to show. [This video demonstrates exactly what I was talking about](https://www.youtube.com/watch?v=jlTVIMOix3I), it’s just in one dimension of space instead of 3.
A full description of gravity requires some high level physics which I havent brushed up on in awhile. To fully explain what gravity we need to explain relativity which means plotting space-time trajectories on penrose Diagrams and… yeah im not going over all that in a reddit comment. I will however try to present the general idea.
What are the fundamental forces?
The 4 fundamental forces of the universe: gravity, electromagnetic force, the strong nuclear force and the weak nuclear force. Out of these 4, gravity is the odd one out. It is 100x weaker than the second weakest force, electromagnetism, which is why your scrappy refrigerator magnet can resist the entire gravitational pull of the earth.
Why is gravity so weak?
The big secret is that gravity is not really an active ‘force’ like the other 3 forces, so much as it is a passive characteristic of curved spacetime. It just so happens that spacetime itself has the geometrical property of passively bringing areas with mass together.
But what does that mean?
Heres a lower dimensional analogy: If you pick two points and draw a set of parallel lines on a piece of paper or other flat plane, those lines will never intersect. They will be parallel forever. Is there a “force” keeping them apart? No its a natural characteristic of parallel lines to stay separate in a flat plane.
Now lets do the same thing but on a globe or sphere like object. Pick two points and start drawing parallel lines, this time those lines will magically come together no matter which points you start with. Is there a ‘force’ that brings those lines together? No, its a natural characteristic of a curved surface. Different kinds of surfaces can dictate how objects in it behave without imparting an ‘active force’ on said object. While this doesnt explain gravity, it does explain why the ‘curved’ part of ‘curved spacetime’ is important.
What is space made of?
Its a big misconception that space is empty or made of nothing. Space is much a tangible thing even when you take away all the matter and energy in an area to create a theoretical perfect vacuum. There is still something there: space! (and countless virtual particles poping into and out of existence but lets forget about that)
What Is Space?
Physicist think of pure space as a kind of membrane that extends and envelops every inch of our 3 dimensional universe. It can do things like stretch, contract, and vibrate. Matter not only exist within/out of this membrane, but more importantly this membrane can interact with matter and vice versa. Mass causes space to bend and curve around it.
Interestingly from some theories of quantum mechanics take the perspective that matter is really just vibrating energy packed a certain waveform. The universe is made of infinitely many vibrational energies and ’empty space’ is just the lowest possible frequency of those energies. The theory of gravity fails at the quantum levels, the search for a grand unifying theory of quantum gravity to bridge the theories between the macro world and quantum world is one of the most sought after theories to this day that the smartest people alive cant piece together.
What does gravity “look like”?
You can think of gravitational force like a bubble or force-field around an object that grows in strength and size proportional to the objects mass/density. Gravitational force follows an inverse square law meaning that it looses strength exponentially the farther you get from the center mass. You may think only cosmic bodies like planets or stars can bend space but actually all objects big and small will bend a proportional amount of space.
Some stranger aspects of gravity:
A really wierd property of gravitational force is that its range is infinitely large. Meaning that every object in the universe interacts with every other object in the universe through an infinitecimal amount of gravity. you are excerting *some* amount of gravitational force on not only the sun but every other cosmic object in the universe, and every cosmic object imparts *some* gravitational force on you. *some* meaning a non-zero number but its so tiny that its as close to zero as a real number can get.
Gravitational Space Waves
Gravitational waves were long theorized but just proven in 2015 after LIGO detected them emminating from a binary black hole merge event. Meaning those black holes were chonky enough to literally beat against the fabric of reality hard enough to cause a vibration wave to propagate across the universe at the speed of light. Wicked stuff.
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