MigL

We previously took advantage of Quantum Field Theory for the EM field, since the all-pervasive QED field gives rise to the associated particles via the Dirac equation and relativistic Shroedinger equation, just to satisfy your need to have 'something to pin it on'. And we could use the color field of QCD similarly for the strong force. But I'm afraid we can't help you with gravity,Mike. We don't have a quantum field theory for gravity, all we have is a classical geometric theory. For now, you're going to have to be satisfied with 'the geometry is the field'. Pin it wherever you'd like.

Mike, if you expect Strange to hand you a 'clump' of space-time, that's not gonna happen ! Space-time is the geometry of the universe in three dimensions of space and one of time. A map of events, if you will. As Mordred explained, a contour map is modified by elevation to show a 'curvature'. This curvature is evident by the co-ordinates of the map having reduced or increased separation. And as Markus explained ( much better than I did ) space-time geometry is modified by mass-energy to show a 'curvature' ( in 4D this time ). This curvature ( the changed separation between events in space-time ) is what we call gravity. ( I was glad that you picked up on the Equivalence Principle between acceleration and gravity )

You've got it wrong, Ten oz. I don't think iNow is accusing you of underestimating D. Trump. He's saying don't underestimate the stupidity of voters ! ( and citing BREXIT as an example )

And of course, in the example you use, if the on-board clock is adjusted forward to be equivalent to each clock you pass, then each clock you previously passed and 'syncd' to would have been put back. How is this relevant to your argument ? As swansont notes, you're changing the parameters to give the ( apparent ) desired result. If you continuously monitor both the on-board clock and the other frame's clock, you will only ever see the other frame's clock moving slower, such that it's continuously lagging ( wrt the on-board clock ). If you observe at intervals, you will see the other frame's clock losing more and more time ( WRT the on-board clock ), giving the APPEARANCE that its running backwards.

We have a model called GR which is based on relationships between events ( space-time co-ordinates, x, y, z, and -ct ). The distance between events, s, is calculated using Pythagoras, such that a 'shortened' distance between events results in 'curvature along one or more of the four axis. It is this curvature which leads to geodesics, and which manifests itself as gravity. This model makes impressively accurate predictions and descriptions of reality. Or rather of our mental model of reality, since what we consider reality is also an interpretation our brain makes in response to certain sensory inputs. Does 'reality' really curve ? Who knows, but the model really works !

The rocket moves by a stationary ( wrt the rocket ) clock, and the onboard clock shows the same time as the stationary clock, say 12:00. The rocket rider waits 24 hrs and checks again ( using a telescope of course ) and notices the stationary clock is only showing 11:00. Since the rocket rider's subjective time hasn't slowed and seems to be running normally ( to him ), it APPEARS the stationary clock has jumped back one hour. IT HAS NOT ! It has simply moved slower ( as measured from the rocket's frame ) such that only 23 hrs have elapsed in ( the rocket frame's ) 24 hrs. No clock will ever actually move backwards. ( I think even grampa's own graphic uses the wording 'appears to' )

Think of a sheet of graph paper, AJB. Changing the spacing of co-ordinates is a way of describing intrinsic curvature. And one could then make the argument ( admittedly with a lot of hand waving ) that changing the spacing of co-ordinates is akin to changing the density of space-time. You're right, extremely 'messy', but it might work. The dynamics ( and nature ) of this field, which I wrongfully assumed was simply co-ordinate in nature, are what's central to his idea. And I don't believe that has any validity.

I don't really have a problem with describing GR in terms of a space-time density. If we consider the typical 2D reduction ( in order to better visualize it) of the depressed rubber sheet with a mass on it, we can get the exact same equations of motion by using a variable spacing of the co-ordinates, i.e. a density. And I've had this discussion with you before AJB, where I spoke of GR as a geometric theory, but you corrected me by saying that it is a field theory where the geometry is the field. So Declan's interpretation, while not mainstream, certainly doesn't change GR. But that's not the OP, is it ? What I really have a problem with is how this geometric field ( essentially a co-ordinate system ) can flow, disappear ( or sink ) into a Black Hole, and, in order to satisfy continuity, must be sourced elsewhere. And that idea is central to his claim to explain galactic rotation without dark matter.

A clock will move faster or slower WITH RESPECT to another clock, giving the APPEARANCE of having moved backwards. No clock will ever move backwards. As a matter of fact, any SINGLE clock ( without comparison to another frame ) will only ever measure 'regular' time.

Wow ! But I guess if I was a Chinese billionaire or government official ( the two are probably the same ), I would be worried about the billion poor people rising up and demanding their share of the pie. China has a revolution coming real soon, and the advantaged will do anything to retain power and wealth.

The procession of Mercury's orbit is usually explained in terms of space warping close to a massive gravitating body.

"The key thing about black holes is gravitational collapse - the gravitational field cannot escape the same way light cannot" So how does a BH manifest its gravitational field ? If its continuously 'eating' space-time ( AKA its field ) then test masses are NOT falling into the BH because of its field, but rather because of entrainment with the infalling space-time. This is completely at odds with GR, unless the two effects are exactly equivalent. But GR has been shown to be effective and accurate, even in the case of orbits about massive BHs. And if the two are exactly equivalent, you haven't brought anything new, just an alternate model. ( but one which still doesn't adequately describe this 'flow', and the sources supplying space-time for the BH sinks )

How come no-one has proposed 'best two out of three' yet ?

Are we voting already ? The year's only half over. I'm sure there's much more to come !

Congrats ! You've often demonstrated a great demeanor and willingness to help here. I'm sure your undergrads and masters will appreciate you as much as we do.

I'm not understanding the concept of space-time 'flowing' either. Especially with the notion of a BH sink and, therefore, a source. I don't think it can simply be explained away as similar to expanding space-time, since that simply implies distances between co-ordinates ( events ) becoming larger. There is no actual 'flow'. What would it be flowing relative to ? And if there are sinks in BHs, where are the sources ? And what process is 'creating' space-time at these sources ?

Quantum particles involved are charged, spin 1/2 particles that are solutions to the Dirac equation such as the electron/positron, and photons, which I believe are solutions to the Klein-Gordon equation.

Swansont's post above is a great example of constructive criticism. It doesn't say you have nothing, or you're embarrassing yourself. It points to a way forward, which will either allow Declan to discard his idea or modify it accordingly. Like I said, I don't think his idea will fly either, mostly because I can't think of a way space-time would flow ( and sink ). You guys are the experts, you provide guidance, in the way of knowledge and critical thinking; Should you be a little more forgiving of new members and not scare them away ? ( luckily, I'm either thick-skinned or too dense to get the hint, and stuck around after I first joined )

It seems that Declan's intent is neither the modification of Newtonian gravity, nor 'unseen' additional matter. He is looking for a third way out of the dilemma. I think that's commendable, albeit speculative. But the again, both MOND and DM are speculative.

Yes, according to the QED model, the field is there , permeates all of space, and gives rise to its associated particles.

In addition to AJB's comment, mass and weight are not the same thing. Weight is the interaction of mass with gravity, and of course, it'll be different for different gravities. I don't see how this implies a relation between the Higgs field and gravity.

At the risk of being mean ... All the comments you guys have applied to Declan's idea could just as easily be applied to the dark matter idea. We have no idea what dark matter is, nor does it have a physical basis, Strange. It just gives the appropriate rotation rates for large scale structures and lensing around them. Not that I'm saying his idea has merit ( I haven't looked into it enough and some definitions seem wonky at best ), but what if I was to pose similar questions to you guys about dark matter ? Could you answer questions about the mass of particles comprising it ? Without DM mass, what equations can you provide for its gravitational effects, Swansont and AJB ? Cut him some slack... The best scientific tool is an open mind.

That's been done too ... District 9

What about all this talk about Scotland already being in negotiations to stay in the EU ( its been clarified that they cannot veto the decision to leave ) ? And what if the Scots have a referendum of their own ( also already in the works ) asking the people of the UK if they want to leave the EU at the risk of breaking up the UK ?

Not in the strict ( or accurate ) sense. It is a 'medium' for the interaction, but not for the transmission. You keep thinking that there needs to be a transmission for an interaction to occur, but that's not the case. You also keep thinking that EM waves require a medium of some sort, and you are struggling to find anything that can be considered a medium. I would abandon this pursuit, Mike. One of the foundations of relativity IS the fact that light does NOT require a medium. Are you willing to be responsible for the scrapping of relativity just so you can sleep ?