Gravity: Caused by the fact that your feet move through spacetime slower than your head.

The Erath's mass causes a drag on the flow of time around it. 

 

 

 

Edited February 25, 20215 yr by martin-w

Gravity is caused by the distortion of space.  Masses distort space, and spatial distortions also affect masses.  Masses seem to attract each other, when in reality they are falling towards each other.

Large spatial distortions do not affect "time" per se.  They cause processes run slower relative to processes that are not in the strong distortion.  So if you park a ship close to the sun, your clocks will run slower than those on earth.

The same thing happens when velocity increases, that is, processes run slower, which is where the idea of time dilation comes from.  One ages slower relative to people whose velocity is slower because physical processes are slower.  What is the analogy between higher velocity through space and a strong "gravitational field"?  I suspect that moving through space also distorts it, analogous to a large mass.

Action at a distance has always been an enigma.  Gravity has pretty much been explained by Einstein, but the real "spooky" action at a distance is how charged particles attract and repel each other.  I have yet to see this adequately explained.  We just know that opposite charges attract, and like charges repel.  This has been explained more recently as due to quantum energy fields and particle spins, but these are more mathematical descriptions, and still don't explain what exactly these "fields" are.  I suspect that space, or spacetime, is somehow involved, although I have no proof this is the case.

My personal belief is that there is, indeed, an ether.  The ether is space itself, and it is what connects everything in the universe.  It also explains action at a distance if it is involved in electromagnetic forces.

This is fun stuff to discuss.  I'm sure a physicist will come along and blow my theory into smithereens.

Dave

 

 

11 minutes ago, dave2013 said:

Gravity is caused by the distortion of space.  Masses distort space, and spatial distortions also affect masses.

Dave

 

 

 

 

You need to watch the video... It explains how gravity is a result of time dilation. The distortion of space is not so important.

 

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Masses seem to attract each other, when in reality they are falling towards each other.

 

Yes, the famous rubber sheet, warped spacetime analogy Einstein gave us. But its not the entire picture, in fact warped space isn't so important, time dilation is. As I said, watch the videos to understand. Might be an idea to watch the video below first, then the first one I posted.

The first video on this is below and enlightening...

 

 

Edited February 25, 20215 yr by martin-w

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Gravity has pretty much been explained by Einstein, but the real "spooky" action at a distance is how charged particles attract and repel each other. 

 

No, we do not know what gravity is, in a fundamental way, we just know how it behaves.  Not definitively anyway.

https://www.newscientist.com/round-up/seven-things-that-dont-make-sense-about-gravity/

Spooky action at a distance is not "how particles repel and attract each other". You have mixed up two different concepts.

Particles attract or repel due to "force carrier particles" passing between them. Magnetism works the same way, by passing photons between.

Spooky action at a distance, a phrase attributed to Einstein, relates to quantum entanglement. How, once particles are entangled you can separate them by any distance, the other side of the universe if you like, and then when you change the state of one of those entangled particles the other changes too, not at the speed of light, but instantly. Einstein didn't like it and believed that "hidden variables" were at work. And that once we had discovered those hidden variables, it would all makes sense.

 

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My personal belief is that there is, indeed, an ether.  The ether is space itself, and it is what connects everything in the universe.  It also explains action at a distance if it is involved in electromagnetic forces.

 

Well yes, there is a kind of ether, in that spacetime itself is a "thing" a fabric. Its not empty, its not a void, its actually jam packed with "virtual particles" popping in and out of existence from underlying fields and then annihilating each other. You could say that science has redefined what nothing is, and that nothing is actually something.

At the fundamental level its about "fields". A multitude of interacting fields. Quantum field theory. A particle isn't at all like a little billiard ball. In reality, a particles is an excitation in a field. A photon is an excitation, or wobble, in the electromagnetic field, an electron is an excitation in the electric field, a quark is an excitation in the quark field, etc.

And if Inflation theory is correct, and there is good evidence, then the hot big bang was a product of the inflaton field that suddenly stopped expanding. And indeed, if the inflaton field (prior to the big bang) was infinite, then the hot big bang may have occurred simultaneously across the entire infinite universe in one go. So what we see now in terms of the expansion of the universe, is actually a change in density and temperature, not a change in size.

On the subject of inflation, namely "eternal inflation", this is why some scientists believe multiple universes must exist.

https://www.forbes.com/sites/startswithabang/2021/02/25/why-do-physicists-say-a-multiverse-has-to-exist/?sh=255b067c4727

Edited February 25, 20215 yr by martin-w

1 hour ago, dave2013 said:

I'm sure a physicist will come along and blow my theory into smithereens.

Well, since you were calling for one 😉. I am not a real pilot, but I do work on quantum physics and Relativity.

The video is by-and-large fairly accurate, but it can easily be misunderstood. Also, it only deals with classical (non-quantum) effects of Relativity, so there is no need to refer to entanglement or quantum fields to discuss its content. John Wheeler (a famous researcher) summed it up quite nicely: "space-time tells matter how to move; matter tells space-time how to curve". It is the curvature of space-time that makes particles move towards a heave mass like the Earth, they basically follow to straightest possible path in space-time.

For slow objects like us, the dominant contribution to curvature is the gravitationally induced time dilation that the movie talks about. That's different for fast objects, such as light. For instance, deflection of light around the Sun is twice as large as one would expect using time dilation alone, because they feel other forms of curvature (a form of space contraction) as well. And things get more complicated if you are close to extreme objects like neutron stars or black holes, but that's not important to understand the movie.

The bottom line is: for slow objects in the solar system space-time curvature and time dilation are basically the same thing. Both provide a description of how gravity affects moving objects, but you can also measure it directly. Most of us do this every day, since the GPS system wouldn't work if time dilation due to gravity (and due to the motion of GPS satellites)  was not taken into account.

Peter
 

12 minutes ago, qqwertzde said:

so there is no need to refer to entanglement or quantum fields to discuss its content.   

Peter
 

 

That was just the way my conversation drifted in reply to David, Peter, he didn't in the video. 

Thanks for your reply. 🙂

So what are your qualifications in this field and what do you do exactly in your day job, if you don't mind me asking? 

Edited February 25, 20215 yr by martin-w

Well, let's just say that I just came back from teaching Relativity (the Alcubierre metric, to be precise) 🙂

Fun fact: my avatar was drawn (a long time ago) by someone who is now the director of a center for computational relativity.

Derek has my vote for this kind of thing.

Google 

veritasium gravity

He even has a highly scientific poll of what people think about gravity.

Subscribe, we need more.

Edited February 25, 20215 yr by WingZ

My head is spinning now 😵

15 hours ago, qqwertzde said:

Fun fact: my avatar was drawn (a long time ago) by someone who is now the director of a center for computational relativity.

 

A very nice drawing. 👍

On 2/25/2021 at 10:12 AM, qqwertzde said:

The bottom line is: for slow objects in the solar system space-time curvature and time dilation are basically the same thing. Both provide a description of how gravity affects moving objects, but you can also measure it directly. Most of us do this every day, since the GPS system wouldn't work if time dilation due to gravity (and due to the motion of GPS satellites)  was not taken into account.

I look at it this way: larger mass causes larger spatial curvature, thus increased gravity.  The greater the spatial curvature, or gravity, the greater the time dilation.  Now, the higher the velocity of an object, the greater its mass becomes, thus curving space more and causing the same time dilation effect.  Is this correct?  If so, then it seems that the time dilation effect is simply caused by the curvature of space.

I think the fellow in the video is making this way more complicated than it actually is.  Time is just movement, really.  It is based on the movement of masses, e.g. fractions of the earth's orbit, or the movement of electrons in a Cesium atom.  Clocks running faster or slower is simply due to the fact that things move slower in a stronger gravitational "field", which makes sense as spatial curvature affects how masses move.

Am I completely off base?

Thanks.

Dave

Hi Dave,

yes, your first paragraph is basically correct. If you know calculus: time dilation depends on the distance d to a planet, so it is a function f(d). Space-time curvature is (very roughly) the second derivative of that function.

As for the video: it actually makes a very nice point. Time dilation can be seen as a change in the four-velocity of an object, which is essentially the local direction of time in space-time. The video tries to visualize this, but I think that one can get the wrong idea about what is happening there.

Peter

7 hours ago, dave2013 said:

 

I think the fellow in the video is making this way more complicated than it actually is.  

Dave

 

Maybe. But he is a professor of physics so certainly knows what he's talking about.