Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
Age wrote: ↑Sat Jul 02, 2022 4:28 am
There are many, many things that we are still trying to understand, but there is no need to keep informing us of this.
I'm not sure why you're taking issue with this.
Take issue ith 'what', exactly?
I am just informing you that, 'you are still trying to understand things', you do not need to inform us of. We know, and already knew, that you are still trying to understand many, many things.
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
It's important to demarcate between things we observe and things we're still trying to understand.
Are you not yet aware that what you observe, and think or believe you understand, is truly not necessarily the case at all?
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
I will continue to use whichever language I feel is best to express subjects because you're not the only one reading. No hard feelings!
And I will continue to inform others of things that they do not need to continually do. Like, for example, keep informing us that there are still things that they are trying to understand.
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
Age wrote:
"Today's galaxies" is a very relative term. As the only galaxy that would exist within the 'today' realm' is the one that 'your team' is within. Every other galaxy 'your team' looks at and observes is really what was happening and occurring before, or in 'yesterday's realm' and term.
Sure, but this is nitpicky when we're talking about very small redshifts.
And, not being so-called 'nitpicky' is WHY there are still so many things, which you are trying to understand.
Once one gets down to the nitty-gritty, then this is WHERE understanding is found.
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
In terms of cosmic time, they are current.
If you say and believe so.
In terms of so-called 'cosmic time', that the Universe began 10,000 years ago, is still very 'current' also, to SOME people.
It is ALL very relative.
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
This would be like complaining that you're not watching a football game in real time because the light took a non-zero time to reach your retina: technically true, but overly pedantic and not constructive.
But considering the Fact that absolutely NO one WAS complaining here, your now complaining is just attempting to over-shadow what is actually and irrefutably true.
It could also be argued and pointed out that you calling what is 'irrefutably true', 'technically true' is just you being 'nitpicky' and/or overly pedantic and not constructive, at all, also.
If some thing IS True, then it does not matter whether 'it' is technically or not technically true.
If it is True, then it is IRREFUTABLE, and a part of what is sometimes sort out in and through philosophical discussion.
And, philosophical discussion is what this forum was set up for, one could imagine.
Also, watching a 'football game' take place, when what 'took place' as already been SEEN, and the 'end score' is already been KNOWN, some might infer is unnecessary.
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
There is a point where redshifts are far enough away not to be well-representative of today's universe, but very short redshifts "ain't it," as they say.
Age wrote:
So, when you talk about 'the universe', you are really only looking at and talking about a part of the whole.
In other fields other than astrophysics when we use the 'Universe' word, or some use the 'universe' word, we refer to Everything, all-there-is, and totality instead.
This way we are not looking at just a narrowed and small picture of things, nor look from a very narrowed and small perspective neither.
Words in the English language often have multiple contexts. I think a reasonable person knows what a physicist is talking about when they mention the universe in a cosmological context.
Does EVERY know that 'you' class 'yourself" as a "physicist"?
Also, is there another way to mention the Universe not in a cosmological context?
If yes, then how exactly?
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
Age wrote:Also, your definition explains a lot about why some people assume or believe that the Universe began and/or is expanding.
These people are only looking at a part of the whole only, and so not seeing what the actual Truth is. Well not yet anyway.
...
Oh, and by the way, is 'cosmoses' an esoteric word that is used in your field, of study?
I'm not sure what you're trying to say here. The universe -- the cosmos, if you prefer -- has a beginning at least to its current state and is definitely expanding.
Here we have another example of the views of the 'religious'. That is, they BELIEVE that what they 'observe' and think or assume is true, is ACTUALLY, IRREFUTABLY TRUE.
Just like those other BELIEVERS who BELIEVED that the sun REALLY did revolve around the earth.
What do you propose the Universe from or of, exactly?
And, I would ENJOY having a discussion about WHETHER the Universe, Itself, is expanding or not. But, sadly you ALREADY KNOW what is DEFINITELY and thus IRREFUTABLY TRUE, and so are NOT OPEN to ANY thing else here.
Also, how MANY 'states' do you envision the Universe has had, and will have?
ANY 'state' could be narrowed down in an attempt to "prove" one's claims are true.
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
These are more than just assumptions, they have the weight of evidence.
The suns movement in the sky WAS also said and claimed to 'evidence' that the sun revolves around the earth.
'evidence' NEVER outweighs 'proof'.
There is NO ACTUAL 'proof' that the Universe BEGAN, nor IS EXPANDING.
There is, however, 'proof' for the opposite. But, AGAIN, sadly most people here BELIEVE what DEFINETELY happens and occurred.
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
I don't know if "cosmoses" is a common term in cosmo or not, but I've seen it. Sure.
I questioned whether the word 'cosmoses' was a word used in your field, of study.
You say you have seen that word before. Do you know what is means or refers to, exactly?
If yes, then will you explain for us here?
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
Age wrote:
So, only 'that expansion', which you could observe, was, supposedly, what was actually 'slowing down'.
But let us not forget that what is, or was, actually being 'observed' may not be what is, nor was, actually happening and occurring. This is because of the misinterpretation of 'observed data' equation, which comes into play. This is also not taking into account APE thinking, which also comes into play here.
I'm not sure what APE thinking is, nor am I sure what kind of point you're trying to make here.
Here we have another example of WHY people took so long to LEARN and DISCOVER, back in those days when this was being written.
Absolutely NO 'curiosity' AT ALL, as seen, was existing.
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
If you have questions about how we know the universe is expanding, I'd be happy to give details so you can draw the same conclusion yourself.
I have MANY questions. First one;
How do you, SUPPOSEDLY, 'know' the Universe, Itself, is expanding. (This is NOT forgetting that this is a philosophy forum, and not some astrophysics forum, so we can use the Universe word in the far more 'bigger' definition and usage here, rather than tiny, little and narrowed definition used in astophyisics.)
In other words, how do you KNOW that the area of all-there-is, totality, or Everything is expanding?
OBVIOUSLY, expansion exists. No one disputes this. So, how we KNOW expansion exists is just obvious anyway. But the claim the Everything, all-there-is, or totality is expanding is a huge claim.
But if you want to still continue to claim that the 'Universe', Itself, that is; Everything, all-there-is, or totality is expanding, or even began, then please let us in on how 'you', and maybe some "others", supposedly KNOW this.
I would love to see those 'details'.
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
Age wrote:
This plot is only a part of, and so does not take into account all of.
This plot is only of what was observed, which let us not forget only what happened and occurred 'previously' and so is not necessarily what is happening and occurring 'now' at all.
Understanding how the scale factor has changed in the past due to changing density parameters does make a prediction for the future.
Age wrote:Astro Cat wrote: ↑Sat Jul 02, 2022 2:35 am
We are using Type 1a supernovae to constrain how the scale factor has changed over time.
What for and why?
Type 1a supernovae are good for measuring distances. We can correlate the distances to redshift and ultimately the scale factor. The "why" is because understanding how the scale factor evolved in the past tells us what kind of cosmology the universe has: what kinds of energy densities there are, which density parameters dominated and when.
Correct me if I am wrong here, but you said;
"different energy densities have dominated at different times (first radiation, then matter, and now finally dark energy very recently) and the universe expands differently during these epochs." Does this mean that 'dark energy' came much later after the 'big bang', than 'matter' and 'radiation' did?
And if so, then how does this correlate with the claims that expansion was much greater immediately after the 'big bang'?
You have stated after all that;
"when matter was the dominant energy density, the expansion of the universe was actually slowing down. As soon as dark energy dominated, the expansion began to accelerate."
Also, would it be possible to just remove the 'universe' word, so this does NOT interfere with what we are actually talking about and looking at here?
If we want to look at and talk about 'expansion', itself, then that is one thing. And, looking at and talking about whether the Universe, Itself, is expanding or not is another thing.
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
Age wrote:
But the past does not always represent nor always predict the future.
In the same sense that we can't know for certain the sun will appear to rise tomorrow, but that doesn't mean we just throw up our arms and say "welp, science is pointless." I don't understand the point of this objection.
1. There was and is NO 'objection'.
2. That you "saw" and "see" an 'objection' would explain your absurd and ridiculous remark, "but that doesn't mean we just throw up our arms and say "welp, science is pointless."
3. Where and why you JUMPED to that ASSUMPTION, you made here, was from NOTHING I wrote.
4. I was just pointing out and stating a Fact.
5. That I put a Fact, straight after a particular question, is no excuse to jump to an assumption nor claim, which was NEVER being made AT ALL anyway.
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
Age wrote:
Most things, when people do not yet understand them, are explained as 'complex' or evolve/behave in 'complex ways'.
To be very frank and Honest with you there is absolutely nothing here that is evolving in 'complex ways' at all.
I do understand how the scale factor evolves, and to be equally honest and frank with you,
you don't.
OF COURSE NOT.
To be Honest and frank with you, again, this is the first time I have seen and talked about these terms. But this is probably VERY OBVIOUS to you. Especially considering the fact of the forum we are in and the questioning I am proposing to you here.
The reason WHY I am questioning 'you' is so that I can BETTER understand what 'it' is, which you claim here you do understand.
There are also LOT of things that you do NOT understand, but this is WHY I do NOT bring up those esoteric wording and understanding, in a forum like this one.
Now, if the 'scale factor' as you have already explained, and I have NOT misunderstood you, is just the name given to what one considers is the Universe is in Its current or present form or state, when the Universe is being observed, in relation to whether the Universe is, supposedly, expanding, shrinking, or neither, and which are, supposedly, caused by ''density energies', which is either 'dark energy', or 'negative equation', of the state that does not scale with the scale factor of the Universe, which, supposedly, expands the Universe, or the other two 'energy densities', which are 'radiation' and 'matter'.
Which, by the way, I am stil trying to work out what they do, if 'dark energy' 'energy density' supposedly drives the expansion of the Universe, but which supposedly only came about AFTER the other two 'energy densities', but which contradicts the claims made previously that expansion was greater nearer the 'big bang'.
And, this is without looking at and questioning your claims about how the so-called 'scale factor of the Universe' coincides with the 'present state of the Univese', which is OBVIOUSLY continuously CHANGING. As the present state of the Universe is in a CONSTANT 'state' of CHANGE.
So, what this actually means is, if one was looking at things, from a DIFFERENT 'present state', say in one of those other claimed states whent the Univese was said to be 'shrinking', then the 'scale factor of the Universe' THEN would be DIFFERENT, but would also be MADE TO BE defined as
1 ALSO.
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
I'm starting to see why someone in another thread mentioned you among people that think they know everything.
Did you also notice that that one who mentioned me among people that think they know everything was also one mentioned as one among people that think they know everything?
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
It is complex because there are three different density parameters that scale differently over time, it isn't a simple curve.
And, what would ALSO makes this SEEMINGLY 'more complex' is the Fact that the so-called and newly-called or named 'density parameters', which, supposedly, 'scale differently over time' could also NOT be DIFFERENT in relation to the Unverse, Itself,
Sure, the 'rate of expansion', of ANY individual so-called 'bang', would CHANGE or be DIFFERENT, at different times, but there is absolutely NO need to add other words here, which just very simple words would suffice.
Adding these newly formed words and terms, and mixing them in with the Universe word, only complicates things, and which makes things far more complex than they really need to be here.
Now, you say and claim that the;
'energy density' known as 'dark energy', is a so-called 'negative equation of state, but drives the 'acceleration of cosmic expansion'.
And, the 'energy density' also known simply as 'radiation', which is a 'positive equation of state' scales with the so-called 'scale factor of the Universe' and so to does the 'energy density' also known simply as 'matter', but which is neither a 'positive equation' nor a 'negative equation' 'of state' but is rather just 'an equation of state' also scales with the so-called 'scale factor of the Universe', correct?
If this is correct, then 'different density parameters, which scale differently over time' is not really that complex.
This is just part of the naturally, and really, very simple and easy way of how the constantly-ever-changing Universe actually works, or behaves.
Also, there is NEVER any so-called 'simple curves' in the 'vastly different density parameters, which scale differently over time', with EACH and EVERY different 'bang' or 'expansion'. But this is just ALL these 'curves' will be, naturally, and very simply, vastly different.
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
Age wrote:As I can see from those lines that were plotted on a graph, which were made and/or used here, by you;
1. The scale of the Universe is shrunk down to 'try to' 'fit in with' only what is able to be observed at a particular time or moment. And,
2. What the rate of expansion was no one who had anything to do with that 'plot' has absolutely any idea.
Here I think you just don't know what you're talking about again. The scale factor is defined as 1 for the present,
Here I think you just do not, yet, know what I am talking about, and referring to, again. The present, is EVER CHANGING. Therefore, the 'scale factor' as defined by 'you' here, as 1, will also be ever changing. This is because the 'density energy' is ALWAYS CHANGING, and thus the EVER CHANGING 'present' 'scale factor' will also be constantly changing.
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
this is the vertical line on the plot that all lines pass through (as they must, if they would produce a universe that looks like the one we see today). I'm not sure what you're talking about shrinking down.
You claimed that the Universe you refer to is ONLY what you observe. OBVIOUSLY, there is MUCH MORE than just what 'you' and some "others" observe. Therefore, what 'you' and "them" are 'trying to' do is 'shrink down' the MORE to 'try to' fit the MORE into 'your' own little view of things.
Lines on a plot will NEVER match the Correct perspective nor view of the Universe, that is; the MORE that 'you' can see and observe.
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
As for your second point that just amounts to saying "this plot is wrong, because I say so," I reiterate that you just don't know what you're talking about.
Here we have, another, example of;
One SAYING, "You do NOT know what you are talking about, whereas I do. I say, 'you are wrong', therefore I am right, and this is because I KNOW what I am talking about".
Look, I am just going by the actual words written on that plot. Those words are;
After inflation, the expansion EITHER; first decelerated, then accelerated OR always accelerated. Which amounts to saying; "We have absolutely NO idea as to what 'the rate of expansion' was." This can be transferred over to the 'future' section of that plot. The opposing words of what could take place, also reiterates that the ones who had anything to do with that 'plot' has absolutely NO idea of what the 'rate of expansion' WAS nor WILL BE.
As I was saying;
What the rate of expansion was, no one who had anything to do with that 'plot' has absolutely any idea.
Another way of saying or showing this is through the answer, or non answer, given to the clarifying question, What is the AGREED UPON 'rate of expansion' after what is called 'inflation' did expansion 'first decelarate, then accelerate', or, 'always accelerate'?
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
If you want to have a serious conversation and you'd like to know how we arrive to conclusions about how the scale factor changes, I'd be happy to have it. But this sort of baseless, smug denial isn't something that really interests me in suffering through.
If you want to have a serious conversation, with me, then STOP MAKING ASSUMPTIONS and JUMPING to FALSE and WRONG CONCLUSIONS.
The Fact that the 'scale factor' CHANGES, and is ALWAYS CHANGING, was ALREADY A KNOWN Fact.
How 'you' FINALLY arrived at this CONCLUSION, is NOT of ANY real interest to me.
What I am far more interested in is LEARNING how to communicate with a species of beings, which ACTUALLY BELIEVES that what it, individually and/or collectively, CURRENTLY BELIEVES is true, at ANY PRESENT MOMENT, is IRREFUTABLY TRUE. The Fact that they have been SO Wrong, SO OFTEN, one would HOPE would make them LESS "BELIEVERS", but SADLY this is NOT the case.
Now, AGAIN, if you want to INSIST that 'expansion' exists, and 'its' rate CHANGES over time, then this is and WAS just common knowledge, and ALREADY KNOWN. However, if you want INSIST, and/or PERSIST, that the Universe, Itself, is 'expanding' and/or 'began', then let us continue on with this conversation/discussion, which I would LOVE to SEE and KNOW how 'you' arrived at that conclusion.
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
Age wrote:WHY is there an assumption of an expanding universe firstly, to begin with?
Because we observe redshift in every galaxy that overpowers the peculiar motion (Doppler effect) out to a certain redshift, generally past the Virgo cluster.
So what?
I have ALREADY partly explained, in this forum, (not that you would be expected to have read nor be yet aware of), that 'redshift' explains 'expansion'. But, redshift does NOT explain, NOR is 'evidence' for the Universe, Itself, expanding.
What you are saying here would also be like those ones claiming the sun does revolve around the earth because we observe the movement of the sun, revolving around the earth.
What NEEDS to be UNDERSTOOD here is that what is 'observed' is NOT always what ACTUALLY is happening and occurring, nor is ALWAYS what ACTUALLY happened and occurred.
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
Since cosmological redshifting dominates peculiar redshifting/Doppler redshifting, the only viable explanation is an expansion.
Which NO one here is DISPUTING, and especially NOT me.
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
I would post some helpful plots, but you asked me not to do that (I will if someone asks, though).
Are they 'helpful' in explaining or showing that the Universe is expanding, or that there is an expansion?
If it is the former, then I would LIKE to see them.
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
Age wrote:
I was wondering what you now say is 'radiation', which is said to be the positive equation of state that does not scale with the scale factor of the universe, and what it does?
In other words if the 'negative equation' 'dark energy' drives the acceleration of (cosmic) expansion, then what does the 'positive equation' 'radiation' drive or do?
If 'radiation' and thus the 'positive equation' do nothing, then just say so.
If 'radiation' and 'positive equation' do something, then just say what that is.
(As for what 'matter' does this is already known anyway, correct?)
Once you clarify this, then we can move onto other things.
Quick correction on what might be a typo in your response. Radiation
does scale with the scale factor, so does matter. Dark energy is the only energy density that doesn't scale.
Okay, and that was NOT a 'typo', that was completely my MISTAKE. You had written:
Energy densities with a positive equation of state (w = 1/3) and scales by /a^4 is simply radiation.
Energy densitites with an equation of state w = 0 and scales by /a^3 is matter.
Which I ASSUMED, Wrongly, that because there was an 'energy density' "with an equation of state", that this would then mean that this one does 'scale with the scale factor of the Universe, while the 'positive' and 'negative' ones would not. Again, my MISTAKE, and my APOLOGIES for ASSUMING some thing. (This is just further PROOF of WHY I say ASSUMING is NEVER a good NOR right thing to do here.)
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
I still don't know what you mean by asking what it does.
I was, again, ASSUMING that if 'dark energy' 'energy density' drives acceleration of expansion, then the 'energy densities' of 'matter' and/or 'radiation' would be said to do/drive some thing as well. As I said, if they do not do any thing or do drive any thing at all, then just say so. But if they do/drive some thing, then just say that, as well.
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
I suppose a relevant thing to say is that radiation and matter energy densities work against the expansion; they would slow and eventually reverse the expansion on their own.
I just found where you had already answered my question. You wrote:
different energy densities have dominated at different times (first radiation, then matter, and now finally dark energy very recently) and the universe expands differently during these epochs. For instance, when matter was the dominant energy density, the expansion of the universe was actually slowing down. As soon as dark energy dominated, the expansion began to accelerate.
When was 'matter' the 'dominant energy density', exactly?
But if you do not know when, exactly, then roughly would suffice?
Also, how would 'radiation' and 'matter', supposedly, slow, and eventually reverse, 'expansion', on their own?
Furthermore, 'radiation' being, supposedly, first, would imply, according to your claim here, that the 'rate of expansion', if it was not reversed/contracting, "in the beginning", was much slower, which opposes what some others say and claim. And, when you say 'dark energy' only came about in a time 'very recently', when was this 'very recent' time, exactly, or roughly?
Astro Cat wrote: ↑Sat Jul 02, 2022 5:59 am
Age wrote:
Furthermore, if you hit the quote button, instead of copying and pasting or writing our names, it makes it much easier to go back and research over what we had previously actually said and written.
The first quote in my responses always have the little arrow thing, I find it's faster just to type things out after that rather than going and copy/pasting that whole thing.
You would only have to copy once, and just paste every other time, but if it is quicker for you to do this that way, then all good. At least you do have the little arrow thing in there at least once. Which is all that is really needed and a lot more than other posters will do.