MigL

Thanks for that Joigus.
It does relate to scale, as my original assertion was that at  Planck time, or at Planck scale, physical geometry might vanish.
And I've been unsuccessfully trying to make my position clearer to Genady that, while 'textbook' geometry does allow for singular points, the physical geometry of space-time cannot support such structures.
IOW infinities are useful, and fine, in mathematics, not so much in the Physics of the real world.

Textbook geometry might be fine with singularities, but I don't think space-time geometry is.
My opinion; take it for what it's worth.

OK.
I like all the older ones up to and including Voyager, and I like Strange New Worlds.
I hate everything in between.
I didn't know you wanted me to be specific, or that anyone was that interested in my likes and dislikes.
 

As I said 

25 minutes ago, MigL said:

Any field will have an associated energy density, and any energy, be it in the form of mass, stress, or momentum, will be a source of gravity. Even the gravitational field itself, is a source of gravity.

It may, however,  have been global, as local would require a specific field configuration, not a homogeneous isotropic energy distribution.

1 minute ago, Genady said:

It fails if the geometry is not sufficiently smooth.

Exactly.
As happens when geometric curvature goes to infinite at a singularity.

Maybe we can just agree that science itself has no bias, but it is done by humans, who do have biases.
I, myself, prefer LQG over Sstring Theory.
And TheVat and I prefer the older Star Treks over the newer ones.

6 hours ago, Genady said:

Why would I try to show an example of GR without geometry? 

GR is a geometric theory.
Any geometry can be used by ( a version of ) GR to define that space-time.
For example, a specific 5dimensional version of GR can be used to describe space-time with EM fields ( see Kaluza-Klein ).
Absence of ( or undefined ) geometry makes GR fail.

But if you don't wish to provide an example of GR without geometry, you don't have to.
 

1 hour ago, Airbrush said:

Cosmic inflation happened before the universe started to "pull" on matter through gravity?  That's how it expanded so fast because there was no gravity to slow it down?

Any field will have an associated energy density, and any energy, be it in the form of mass, stress, or momentum, will be a source of gravity. Even the gravitational field itself, is a source of gravity.
The symmetry break that precipitated the decoupling of electromagnetism from the weak interaction, and the acquisition of mass for leptons, quarks and some bosons, was due to a false zero energy level.
It was the slow roll down from this false zero level that provided the impetus for inflation, which I thought happened between 10^-35 and 10^-32sec.

On 6/2/2024 at 8:07 AM, Genady said:

ailure of GR does not necessitate failure of geometry.

GR defines space-time using its geometry; if there is any 'geometry', GR can use it to describe the space-time.
For GR to not be applicable there has to be an absence of 'geometry', such as geometry becoming infinitely curved.
Or can you show me an example of GR describing a space-time without 'geometry' ( does that even make sense ? ).

There are two types of time dilation; one due to motion relative to the observer, and the other due to depth in a gravitational potential well relative to the observer.

In the first case we would notice time dilation of distant galaxies if they were moving away from us, but this effect would be non-linear ( as Mordred has explained ) since dilation increases asymptotically as c is approached. The Hubble expansion constant is, however, just that, constant, and mostly linear ( except for the slight up-tic due to accelerated expansion ).

The second case would involve everything we observe, in all directions, being deeper in a gravity well than we are, in order to see a time dilated red shift; and that makes no sense due to the shell theorem.

If you know of another type of time dilation, please educate us ...

Ah, so many 'wanna-be' Philosophers who think the universe resides in their mind, and its reasons and workings can be divined in their own heads.

Good Philosophers temper their ideas with science and evidence based facts, before attempting to preach to us peons.

2 hours ago, TheVat said:

It's a bit like the Star Trek Discovery rubber science idea that outer space is permeated by a mycelium

Or the weapons used by the android world at the end of Picard S01, that looked like flowers.

Maybe they should call Swansont back to consult on the science, as all the new shows are destroying a dynasty, and I will not watch them.
Except Strange New Worlds, which I like.

If you don't wish to build anything, there are, at least for infrared, 'off the shelf' cameras that can be purchased, which detect infrared sources and dispay them on a screen.
I used to use one for detecting integrated circuits that had failed ( or were close to failing ) and heating up due to excessive power draw.

Digital multimeters are available for $20 on eBay/Amazon for detecting low voltages and low currents on automotive or digital circuits.
If you are going to test for voltage/current on your mains or higher, I suggest something with good protection, like a Fluke.
The cost will be much higher, but there's nothing worse than testing a 300 or 600 volt circuit, and having your meter blow up in your hand and catch fire.

Well, to be fair, he did say

12 hours ago, curium96 said:

There is no debating fact where fact is indisputable

and, true to his word, he didn't present any, and there is nothing to dispute or discuss on this discussion forum.

Might as well close the thread, then.

Why all the comparisons of human designed airplane wings to bird wings ?
The first flying machines were balloons, and had no wings.

Oh, and I could design a much better system than these crappy eyeballs I have in my head. The Nikon autofocus and stabilized lenses for my camera aren't prone to hi pressure and image loss due to glaucoma.

2 hours ago, dimreepr said:

The stage doesn't assume the actor can act...

GR has no stage to act on ...

I have posted that there may be some biases in science, gave a few examples, and even posted my definition of a 'bias' to support my stance.

That being said, science, and the scientific method, is like democracy; certainly not perfect, but way better than any alternative.

I would say that, since GR is geometric, and GR fails on approach to Planck time, any notion of geometry ( spatial or temporal )  is similarly not applicable.

Fields have an energy density; any field will contribute to the stress-energy-momentum tensor, and curvature.

4 hours ago, JohnDBarrow said:

However, Mig (as in Soviet jet?), you failed to answer any of my questions.

MiG is currently a division of United Aircraft Corporation, also including Sukhoi, Tupolev, Yakovlev, Ilyushin and others.
It was originally known as the Mikoyan and Gurevich Design Bureau after the engineers who founded it during the first stages of WW2, Artem Mikoyan and Mikhail Gurevich.
Both have been deceased for over 50 years, and design duties passed on to be succeeded by R Belyakov ( I believe ).

Over the years they have produced iconic interceptor/fighter jets which have sold in great numbers because of low cost and 'simplicity' of operation, including MiG-15 ( Korean war ), MiG-19-21 ( Vietnam war), and MiG-25 ( Iraq, and V Belenko's famous defection in 1976, with vacuum tubes in the radar ).

As with your other thread, I can't take this one seriously either.

@Airbrush Why do your posts often sound like sermons ?

5 hours ago, curium96 said:

Where there is less gravity, time moves faster, right?

The gravitational wells of galaxies are extremely 'shallow'; the galactic voids where expansion occurs, just slightly more so.
The dark energy term ( Cosmological Constant ? ) only slightly exceeds gravitational potential in the voids between clusters, but is not enough to overcome it at galactic scales.
The gravitational potential difference is not enough to account for sufficient time dilation which would explain expansion.

Oh my.
You sure are picking to discuss all the topics that will get you in trouble.

A much more current example would be the 'infatuation' of some Physicists with String Theory.
It has pretty well been shown to lead nowhere, as it doesn't apply to any specific universe, but many possible ones.

Yet the 'beauty' of the theory keeps many Physicists working on it, the thought being that aesthetics make 'right'.
That seems to me, a 'bias'.

Sorry if I seem to be picking on Physicists, but that is what I know.

I would have thought D Trump would just pay off one of the jurors, resulting in a hung jury.
But knowing him, he would have used campaign financing, instead of his own money 😄 .

14 hours ago, JohnDBarrow said:

You tell me how you and I got here, hot shot. 

I don't know about you, but I was born, for the first and only time, as a result of my dad and mom having sexual relations, about 65 years ago.
Do we need to have a 'birds and bees' talk ...

My personal definition of a 'bias' is a subjective like, or dislike, that is not based on available information.
As an example, I know both bread and cake have equal calories, and both are bad for me, but I prefer savory bread, and dislike sweet cake; someone else, with that same information, may like cake, and dislike bread.

This has happened in science, and I still believe early QM interpretations are an example.

That being said, I do agree it is very rare ( but does happen ) in the hard sciences. It is probably ( my opinion, or bias ) more prevalent in the 'softer' sciences, like Psychology or Sociology where multiple 'conclusions' can be drawn from similar observations.
As an example, if a Psychologist links every human interaction to sex, is it a reflection of his observations, or a reflection of his own obsession ?

1 hour ago, swansont said:

Interpretations are personal preference; I don’t see how that’s bias.

Personal, subjective preferences ARE biases.