Is space infinite?

[Elp]

I think if you take a look at what is observable currently, from atomic, microscopic then work out to scale, things exist at different scales relative to the object within its own scale space. There likely is a limit, we'll just never see it.

[Stickey]

30 minutes ago, vlaiv said:

 

Freaky stuff ...

So true. 

Thinking about the subject of infinity is mind expanding to the point of oblivion.

For a start, they're are different types of infinity, as I think Vlaiv had implied. 

Think of integer numbers. The number of them is infinite, but take the number of even or odd numbers, which should be half, they too are infinite. 

Consider natural numbers between 2 successive integers, in theory finite. But the number of real numbers between the 2 is infinite. Even some particular real numbers between the 2 integers are irrational.  I.e., the number of decimal places is infinite. Trying to write out the number is impossible, the number of digits is infinite, but it exists between 2 finite values. 

Then we have mathematical conundrums. My favourite is Gabriel's Horn. Take the equation y=1/x where x >1 and then rotate it around the y axis, it forms the shape of an exponential horn (much loved by hi-fi aficionados of the 70s). You can prove that the volume of the horn tends towards Pi, but the surface area is infinite.  So you could FILL the horn with a Pi pot of paint, but you couldn't actually paint it. 

Like I said, there's more than 1 type of infinity.

[saac]

5 hours ago, Stickey said:

Like I said, there's more than 1 type of infinity.

To see a World in a Grain of Sand
And a Heaven in a Wild Flower 
Hold Infinity in the palm of your hand 
And Eternity in an hour

William Blake - Auguries of Innocence 

 

While some are more poetic than others  

Jim 

[Paul M]

9 hours ago, saac said:

As for dark matter/energy. Why do you think they are fudge factors?  In their absence what do you believe will explain the missing mass and what is causing the accelerated expansion and why would that be more credible than dark mater and dark energy?

They just look so fudgy! It strikes me that they have been invoked to make the missing mass problem go away, but raise even more questions. Perhaps there is an upheaval in cosmology coming our way. I see occasional headlines that suggest cosmology is broken. Maybe it is?

My own theory is struggling to develop, don't bother watching this space 😁

[Paul M]

double post..

Edited July 6 by Paul M

[saac]

35 minutes ago, Paul M said:

They just look so fudgy! It strikes me that they have been invoked to make the missing mass problem go away, but raise even more questions. Perhaps there is an upheaval in cosmology coming our way. I see occasional headlines that suggest cosmology is broken. Maybe it is?

My own theory is struggling to develop, don't bother watching this space 😁

I get where you are coming from but if it is a fudge then it is a fudge with reason behind it. Gravitational attraction would tend to collapse the universe while the expansion forces  would act in opposition. When we see an accelerated expansion it raises the question what is driving this. Dark Energy is then the place holder for whatever (unknown) is causing the acceleration in the expansion.  In a similar way dark matter is the place holder for whatever (unknown) is causing the observed higher rotational velocities of galaxies. So if they are fudges then they are fudges based on observational measurements and confirmed understanding of behaviour.  It would be exciting if the accelerated expansion and the excessive rotational speed of the galaxies turned out to be the result of something even more mysterious (if that were possible). If it does then there is potentially new physics to be discovered.   As for headlines - physics has always been in crisis since Newton fought Leibniz.  Everybody is competing for their share of funding. 

Jim 

 

Edited July 6 by saac

[vlaiv]

Is that bowl of petunia thinking "Oh no, not again .... "?

[Paul M]

38 minutes ago, saac said:

Dark Energy is then the place holder for whatever (unknown) is causing the acceleration in the expansion.  In a similar way dark matter is the place holder for whatever (unknown) is causing the observed higher rotational velocities of galaxies

That's my point, I think. You've given a good definition of "fudge" 😀

Certainly something is afoot, but maybe neither energy or matter in any sense we recognise. Will these "placeholders" be manifestations of one of the known forces or of something yet to be discovered

I just get the same GUT feeling about this as I did for String Theory, and (surely?) that's been put to bed now.

[saac]

25 minutes ago, Paul M said:

That's my point, I think. You've given a good definition of "fudge" 😀

Certainly something is afoot, but maybe neither energy or matter in any sense we recognise. Will these "placeholders" be manifestations of one of the known forces or of something yet to be discovered

I just get the same GUT feeling about this as I did for String Theory, and (surely?) that's been put to bed now.

Don't all theories get replaced as further layers of reality reveal themselves?  String theory was no exception and it had its uses.  I guess as much as it may be frustrating, we only ever hold a momentary interpretation of reality.  Unlikely to be one of the fundamental forces given that we know how these interact.  A yet to be discovered force? Most definitely,  let's give them names, mmm how about  dark energy and dark matter, they seam appropriate given their apparent influence   That is all they are, placeholders for an observed nature, until we can further peel back the layers.

Jim  

[saac]

1 hour ago, vlaiv said:

Is that bowl of petunia thinking "Oh no, not again .... "?

Well spotted vlaiv, you got the reference  .

Jim

[steppenwolf]

On 04/07/2024 at 23:30, Paul M said:

Is cosmology in crisis? I've never like Dark Matter or Dark Energy concepts. Look like fudges to me... (as a sewage worker 🤣)

Look like fudges to me too but then I’m just an ex-printer with a fancy camera 😂😂

[saac]

1 hour ago, steppenwolf said:

Look like fudges to me too but then I’m just an ex-printer with a fancy camera 😂😂

I

Seeing an effect and hypothesising that there must be a cause is not a fudge it's the basis of all science. I'm still curious as to what it is that causes the trouble, is it the observation of the accelerated expansion and higher rotational speeds of the galaxies?  Is it these measurements that you are thinking as a "fudge".  Or is it the suggested causes - an energy and a form of matter?  In that case let's call them Thing A and Thing B  

I suppose the measurements could be incorrect but the Hubble Tension was confirmed by JWST not that long ago. It could of course be that there is an observational effect that we do not know of that introduces error. But for the meantime I think the two candidates are a reasoned response, in fact to not suggest them would be a dereliction or a fudge so to speak! 

Jim 

[MalcolmP]

19 hours ago, saac said:

fudge 

 physics has always been in crisis since Newton fought Leibniz

Newton fought everybody ! and anyway Leibniz won ! But you wouldnt know it from the spin given to Newton these days.

The trouble with fudge is that it is just a word with meaning of good/bad in the ear of the beholder !
If a fudge factor was good enough for Albert (cosmological constant, to explain the static universe as he required when his equations could imply an expanding one , oh my ! how that backfired ) then Dark Matter is good enough fudge pro.tem for me.
Mind u, for galaxy rotation MOND can be an alternative to DM (depending which arxiv paper you read ) but it falls down badly when gravitational lensing is observed. It can only explain certain limited special cases, whereas DM gives a sweet answer in GR, never mind it messes with the standard model of particles.

[saac]

1 hour ago, MalcolmP said:

Newton fought everybody ! and anyway Leibniz won ! But you wouldnt know it from the spin given to Newton these days.

The trouble with fudge is that it is just a word with meaning of good/bad in the ear of the beholder !
If a fudge factor was good enough for Albert (cosmological constant, to explain the static universe as he required when his equations could imply an expanding one , oh my ! how that backfired ) then Dark Matter is good enough fudge pro.tem for me.
Mind u, for galaxy rotation MOND can be an alternative to DM (depending which arxiv paper you read ) but it falls down badly when gravitational lensing is observed. It can only explain certain limited special cases, whereas DM gives a sweet answer in GR, never mind it messes with the standard model of particles.

 

I wonder if Einstein had ever thought of using the term "dark energy" for his "fudge" lambda. How prescient that would have been.  

Ach well, the layers will no doubt reveal themselves in due course; I think the universe is patient.   New proposals/"fudges"  to advance. 

Jim 

 

[steppenwolf]

21 hours ago, saac said:

Or is it the suggested causes - an energy and a form of matter?  In that case let's call them Thing A and Thing B  

This ☝️ - I don’t doubt the observations but to ascribe them to mysterious energy and equally (not mathematically!) mysterious matter doesn’t sit well with me - you will be relieved to learn that I have absolutely no alternative suggestion for what we see but I do like Thing A and Thing B a lot because that leaves things open to one of those two being that we have misunderstood how the Universe works 😂

[saac]

53 minutes ago, steppenwolf said:

This ☝️ - I don’t doubt the observations but to ascribe them to mysterious energy and equally (not mathematically!) mysterious matter doesn’t sit well with me - you will be relieved to learn that I have absolutely no alternative suggestion for what we see but I do like Thing A and Thing B a lot because that leaves things open to one of those two being that we have misunderstood how the Universe works 😂

I could understand your hesitation had they (energy and matter) been ascribed in some random arbitrary manner. However their nomination is I believe consistent with the physics of what we are observing. Thing A and B I can live with, place holders at the end of the day; their nature, matter or energy the universe has already determined and awaits our discovery. No fudges😀

Jim

[Gfamily]

The point is that either:

* Thing A acts in the same way as an energy field would on matter 

* or we need to change the laws of motion.

Similarly for Thing B:

* either it acts gravitationally in the same way as matter would 

* or we need to change the laws of gravity.

MOND is an attempt to change the laws of gravity to account for Thing B, but (AFAIK) it neither has an a priori reason for the required change, nor an outcome that fits all aspects of the evidence for Thing B.