1

Physics, Astronomy & Cosmology / Re: Why can't i understand the andromeda paradox?

« on: 07/08/2022 00:10:00 »

But some physicists are vague about whether the rapid variations in the current age of the distant person (according to the accelerating person) should be considered to be MEANINGFUL or not.  It is possible to show that those rapid age variations (including negative ageing) MUST be considered to be fully real and meaningful.

But you're the one being vague about it since you're not giving any definition of 'meaningful' here, except to put it in caps, which signifies it being shouted.
For instance, I can face Andromeda and say it is 2.5 MLY in front of me. Now I turn my back and it suddenly is 2.5 MLY behind me, 5 MLY from where it was a moment ago. Is that a MEANINGFUL change in location? I don't know your definition, so I can't answer, but that's all that's going on in the Andromeda scenario.

And while I have you on the horn, please stop copying your personal theories into the main sections of the forum. You have your own thread for that, and your own paper (full of mistakes) to which I left your link intact there.

2

New Theories / Re: If there was one Big Bang event, why not multiple big bangs?

« on: 06/08/2022 04:00:31 »

Olbers's paradox ... says that the darkness of the night sky conflicts with the assumption of a ... static universe.

Well, thermodynamic law also conflicts with the same thing. I don't think this qualifies as a paradox, it is a mere falsification of this 'static universe' suggestion, something that was presumed right through the 18th century.  You sort of propose one yourself, and thus contradict these observations.

3

Radio Show & Podcast Feedback / Re: Food waste, from The Naked Scientists 2 August 2022

« on: 05/08/2022 21:47:26 »

are on the "Sell By" date. Very much reduced in price, and thus about to be tossed, but still good to eat for a while more.

Indeed. Too many confuse sell-by with eat-by.

are all in the freezer

But you can only do so much of this before the price of storage exceeds the savings you got buying it on the cheap. Things stored for months, unless unavailable later, are often more expensive that just buying at the current price and eating it fresh.

grapefruit outside is not showing any signs of bearing fruit this year,

Alas, my zucchini leaves are being eaten by something each night. They're not likely to ever bear me an actual zucchini.

Even saved more money, walking to the shop and back.

I've done it with a bicycle sometimes, but it's just too hot to do that with perishables right now.

4

Physics, Astronomy & Cosmology / Re: How many levels of orbit can a planetary system sustain?

« on: 31/07/2022 23:00:28 »

I suppose a lot depends on one's definition of orbiting something else.
If two identical mass objects orbit each other, is that an orbit on your list, or does one (Earth) have to be larger than its satellite? If so, what is the smallest ratio of primary to secondary?

5

Physics, Astronomy & Cosmology / Re: How many levels of orbit can a planetary system sustain?

« on: 31/07/2022 22:57:33 »

The ratio can be far less than that.  Charon orbits Pluto, and its mass is a whopping 12% of the primary.

Mathematically, there seems to be no limit to the number of levels for at least reasonable stability. True stability cannot be achieved in any 3+-body system.

One can add levels to the other side as well, say by having our sun orbit some larger star well away from our local solar system, but it needs to be quite far away to not disturb the orbits of the more distant things. So best way to get a lot of levels is to not have a lot of separate things (planets) orbiting any one thing.

6

New Theories / Re: Can a photon escape from inside the event horizon of two black holes?

« on: 25/07/2022 18:34:57 »

It isn't something that needs references, so you should not be demanding any. If your model doesn't conform to the requirements of STR, it will enable you to measure absolute speeds with ease, so GTR has to include STR as part of itself in order to fit observations.

I do see what you're saying here. If it was just an absolute interpretation of GTR, any empirical claim of GTR would also be an empirical claim of this alternate interpretation. But then it must also conform to GTR’s geometry, and your assertions deviate from that. Hence the need for references since the equations of GTR only work with GTR geometry.
Calling a hypothetical unwritten theory ‘ LET’ seems a mistake. Still, the references you indicate here are not needed when talking about this alternate nameless theory. There's the Schmelzer absolute ether theory which I will call SET for lack of a better name.
The references for which we're asking are the ones that violate GTR:

GTR also has to conform to our 3D Euclidean view of events while doing its 4D stuff

But GTR includes the effects of gravity and thus is not confined to Euclidean 3D space like STR is. Space is not Euclidean under GTR, so if it is under the hypothetical LET theory, it no longer can use GTR mathematics, and we need a reference for the new mathematics that maintains consistent empirical measurements. You don’t give this because no such theory exists.
SET does not suggest Euclidean 3D space as its preferred frame. The frame is the harmonic coordinate condition, a coordinate condition in GTR which makes it possible to solve the Einstein field equations. This is a non-linearly expanding metric, which Euclidean space is not.

SET is not just a trivial hand-wave, saying everything GTR says is true, but there's a preferred foliation. It derives everything from completely different premises. It very much has differences.  Like any absolute interpretation, the preferred frame doesn't foliate all of spacetime, so black holes, wormholes and such cannot exist. There can be no black hole event horizon at all. The big bang must be replaced by a big bounce, perhaps to solve the issue of 'something from nothing' that you get with a model with the universe being contained by time, instead of time being contained by the universe as in GTR, but I didn't actually see if SET posits universe contained by time. LET doesn't posit this, but nLET (another incomplete theory) does.

LET describes what you get in that 3D Euclidean view

That's the claim that needs the reference. A 3D Euclidean view with slowed physics makes different predictions, such as the angles of physical rigid triangles adding up to 180°. You're essentially making claims of a nonexistent theory. If space is Euclidean but light (and other motion) merely slows down based on the dilation equations for gravitational potential, you'd get different times for light to get from A to B through a gravity well. By positing this Euclidean assertion, you throw away all the mathematics of GTR that uses a different geometry, and yes, this completely new way of doing it very much does need a reference.

The two ways of looking at it necessarily map to each other and you don't need a reference to understand that.

I actually agree with this, but if they map to each other, then the space under gravity is necessarily non-Euclidean. SET (the only generalization of LET of which I am aware) does not agree with your assertions.

That's why whenever I employ LET as a tool for viewing the action

If you're matching GTR descriptions, then you’re using GTR despite calling it LET. If you're making up new rules that contradict GTR, then it needs an actual theory behind it to make the new predictions since the GTR mathematics no longer apply. That needs justification, or it is just 'making up your physics'.

When LET and STR tell you what these lines of black holes

Neither LET nor STR deal with black holes.

... what these lines of black hole look like as they approach each other before the gravitational interaction becomes significant (due to the extreme contraction of the gravity wells - no amount of applying GTR can change that because the gravity acting on each line from the other is so weak up to that point and cannot affect the 3D Euclidean view of the action)

This assertion not backed by mathematics. I tried to point this out in an earlier post, but you don't seem interested in actually working it out. This is another reason for the topic to be in new theories.

"What [the boat] it zigzags downwind and there's very little drag against the water? It might be able to go downwind faster than the wind." Someone might then object by saying, "Nonsense: by definition a sailing boat cannot go downwind faster than the wind, so you cannot be talking about a sailing boat!

This is entirely valid. Based on the definition of sailing boat you gave, the thing you describe isn’t a sailing boat. Ditto for event horizon.
We did have a thread on a sailing ‘car’ that did go directly down wind (no tacking) faster than the wind, or even directly upwind. With a similar definition, we’d have to call it something else.

Guess what the LET in CLET stands for. Doug Marett's site dates back before that and deals with LET and how it covers the same ground as GTR. You ought to remember this page; http://www.conspiracyoflight.com/Conspiracy.html

Ah, an actual reference! I was actually wondering if you would bring up this crackpot site.

I invite to to cite sources for your claims, and not sources from science denial sites.

conspiracyoflight is very much a science denial site. It asserts that GTR and even STR is wrong, so if it asserts that CLET makes the same claims as Einstein’s theories (as you do), then it follows that CLET is wrong. I doubt they piggyback off GTR since it attempts to debunk Einstein at every possible turn.
It became a classroom exercise to take any random article listed on that site and find the flaw in it. It isn’t difficult. Pick one if you want a demonstration. This is actually the site you choose to back your claims?

the necessity of both theories to generate the same 3D view of the action as they're applying the same maths, there is no cause to dispute them.

But you’re asserting an alternate 3D view, so the dispute stands.

People who actually work on LET with this simple addition of having light slow down in gravity wells do call it LET.

OK. That claim come right from GTR, so they can stick on the label if they want, despite the lack of an actual theory that does it. But when the claims diverge from GTR, then it becomes something that needs backing since the backing of GTR is lost.

I did explain why your idea that a line of black holes doesn't suddenly have a single singularity in it the moment the event horizons connect.

I never asserted otherwise.

7

New Theories / Re: Can a photon escape from inside the event horizon of two black holes?

« on: 24/07/2022 15:00:21 »

Only by denying said action [within black holes] at all. There is no 'in them' in any preferred frame model.

You get more irrational by the year. There are objects which science has discovered and called black holes, and they have event horizons. There is an inside and an outside of an event horizon.

This is using Einstein's model, not a preferred frame model. To my knowledge, no preferred frame model has an event horizon at black holes since there  are no events on the other side to define one. I may be wrong about this, so kindly put in the citation. Your lack of citations reduces your posts to mere assertions. LET does not make the claims you ascribe to it.

You're the one making thing up here by misunderstanding things and misrepresenting my position.

Misunderstanding your position isn't 'making things up'. You asserted valid physics in Euclidean space. You asserted action (or even space at all) within black holes in a preferred frame model like LET. I need references for those claims, else you very much indeed are making up your physics. I'd not have moved the thread just for saying what LET theory posits, but you seem to simply be attaching the LET label to your personal ideas. That puts the topic here in new theories.

It is a matter of fact that the predictions of LET and GTR match up perfectly for all observations and experiments - there's already been a link in this thread to the wikipedia entry on LET which spells that out.

Wiki spells out something entirely different. It says LET in only an interpretation of special relativity and thus matches the predictions only of SR because it had never been generalized.

The non-existence [up until apparently 2012] of a generalization of the Lorentz ether to gravity was a major reason for the preference for the spacetime interpretation.

Wiki says an entire century went by without LET having a theory of gravity. The one in 2012 is not called LET as far as I know, and it does not back your claims as far as I know, but I invite your to prove me wrong.
In particular, when does say an infalling particle actually get inside a black hole? How long does it last there? These questions are meaningful in an interpretation with absolute time.

It is not disputed by serious physicists, so what's your game?

I'm disputing your personal claims, not disputing anything on which serious physicicts have commented.

and this maintains Euclidean geometry while providing the same precision in its predictions as GTR.

This is the first assertion. If physical triangles (made of rigid rods say) have angles that don't add up to 180°, it is hard to argue for Euclidean geometry. From where does this claim come?

It comes from the fact (acknowledged on that wikipedia page) that the predictions match and that LET achieves this using Euclidean geometry with the speed of light slowing instead of trying to cram extra space into gravity wells while maintaining the speed of light at c.

Wiki says nothing of the sort. I'm looking at the LET page ES linked. Kindly quote the text you think says this. The article I see says LET doesn't have a theory of gravity at all, per the line I quoted above. It says nowhere that LET is a mathematical abstraction of GTR.

LET is an alternate interpretation to only Special Relativity, never to GR.

Let me repeat: LET accounts for gravity by having light slow down in gravity wells, and this enables it to match up as perfectly to observations and experiments as GTR, so you're simply wrong.

Perhaps so, but citation needed. It certainly doesn't say that on the wiki page, which actually says that LET doesn't account for gravity at all.

You said,

There's no 'long black hole'. If you put the little ones close enough together, you get one black hole, and the event horizon of it is more or less spherical (assuming minimal total angular momentum). There's no such thing as a line of barely linked black holes. I spelled out why in my prior post, which perhaps you're not bothering to read. Tell me why my explanation is wrong if it is, but don't just keep repeating refuted stuff. I lay no claim to be necessarily right on this stuff.

So, that had to be corrected, and it just added to your drive to hide this thread in the subforum bin dominated by mathematically illiterate ramblings where hundreds more of your errors are stored. You have to move my threads to hide your errors just as much as to defend the establishment's broken models.

This fails to tell my why my explanation is wrong, and didn't even bother to quote the explanation itself. Your purposes seem to be evangelism and not actual science. A scientist would back his claims, and would demonstrate how erroneous explanations such as the one you didn't quote above are wrong. Instead I get raving assertions of conspiracy.

How can this object move at all through space? If the speed of light reaches zero there, the speed of matter would too, preventing a black hole from moving in coordinate space. It all seems self contradictory.

As I mentioned in an earlier post, the speed of light is slowed relative to the black hole - not relative to the space fabric.

Sounds then like relativity. In an absolute interpretation, speed is relative to the absolute frame an not to any other. It's a property, not a relation. Schmelzer seems to have solved this issue, but seemingly not by the premises you're asserting. I admittedly don't know any of his premises. The premises of SR are not held of course, but the Einstein Equivalence Principle is derived (not postulated as in GTR), which is impressive.

8

New Theories / Re: Can a photon escape from inside the event horizon of two black holes?

« on: 23/07/2022 13:44:09 »

The two theories map to each other perfectly when it comes to predictions of the visible action from outside black holes

Lorentz Ether Theory was, to my knowledge, never generalized to a theory of gravity anytime in the 20th century.  I did find one first published in the 21st century, last revised in 2012: https://arxiv.org/abs/gr-qc/0205035
It differs significantly from your assertions, primarily in the existence of black holes, which is an Einstein-only concept. They cannot exist in a preferred frame model since no coordinate system foliates all of spacetime.

but they diverge when describing the action inside them.

Only by denying said action at all. There is no 'in them' in any preferred frame model.

You see to be making up your physics. I invite to to cite sources for your claims, and not sources from science denial sites.

and this maintains Euclidean geometry while providing the same precision in its predictions as GTR.

This is the first assertion. If physical triangles (made of rigid rods say) have angles that don't add up to 180°, it is hard to argue for Euclidean geometry. From where does this claim come?

the two theories are essentially mathematical transformations of each other (which is why some people consider them to be different interpretations of the same theory)

LET is an alternate interpretation to only Special Relativity, never to GR. It never got gravity right, unless you count theories like the one I linked above, which probably should be called something like 'Schmelzer Ether Theory'. It does have singularities in what it calls 'frozen stars'. The mathematics at the event horizon (GR only term) is necessarily singular in this preferred frame.

I won't go into the details here as this is not a discussion of rival theories.

But you've done so in making these assertions. Topic has been moved accordingly.

The term black hole becomes fuzzy in such a situation, just as it does during part of the time when two black holes are merging and have linked up without their singularities yet merged.

The verb tense usage here suggests there's a meaningful coordinate time at which what you picture as a pair of physical singularities merge after crossing each other's event horizons. I never suggested any such thing.

In LET, the speed of light reduces, reaching zero at the event horizon

How can this object move at all through space? If the speed of light reaches zero there, the speed of matter would too, preventing a black hole from moving in coordinate space. It all seems self contradictory. I don't think Schmelzer makes this assertion/deduction either. Again, a citation would be nice here since I doubt any of it comes from Schmelzer.

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Physics, Astronomy & Cosmology / Re: Can we utilise antimatter to store energy from solar power?

« on: 21/07/2022 21:31:50 »

Can we store energy efficiently and safely using it?

Define 'efficient'.
I mean, for every unit of energy stored as antimatter, it takes over 20000 units of energy to produce it. I cannot think of an energy storage technology less efficient than that, and this assumes that no losses when the energy is subsequently used for the purpose for which it was stored.

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Physics, Astronomy & Cosmology / Re: Star distance appearences

« on: 21/07/2022 01:35:24 »

The OP asked about 'visible' stars in a context of constellations and such, implying it is objects visible without aid of instruments not available to the 'ancient Greeks'.

Hence the list is limited to about 2500 stars (7000 according to @evan_au who apparently lives in a unlikely dark place), the vast majority of which likely still exist today.
The list of potential stars that are exceptions were all particularly nearby and bright things, suggesting that there's a far more boring list of similar candidates that are just barely visible due to their far greater distance. But this greater distance also increases the window in which it can cease to exist.  We see very few dim stars like our own, and most of them are fairly large bright distant stars.

We see at least one galaxy (I can still spot it here without aid despite the light pollution), but no individual stars in it are visible. The galaxy is assuredly still there, so I don't think it counts as something that has self-destructed in the time it took for the light to get here.

If you consider that what you name "stars" are in fact galaxies or clusters of galaxies, it is true that, accordingly to the big bang therory and the expansion that come with it, already 97% of galaxies are actualy, from our point of view, unreachable.
Because 97% of all the galaxies inside the observable universe are recessing faster then the speed of light.

Having a recession speed greater than light isn't what prevents us from getting to most of them. We see them, and they see us, so clearly something is 'getting to them'.  What prevents us from getting to them is being beyond their event horizon, and while that event horizon and the distance where things have a recession rate (measured in cosmological coordinates) greater than c is close to it, it is inside, and we can theoretically reach something currently receding at a rate greater than c. Just not much faster.

In the absence of acceleration of expansion, there would be no point in the universe that is unreachable regardless of recession rate. But there is acceleration, and that means that our local group of galaxies will never reach another group. Our current neighbors are all we will ever have.

At some point, i think that we can say that physicaly speaking they do not exists for us any more.

If you can see it, it physically exists (at least with a measurement definition of 'exists', and I don't know of a better definition), and over time, new objects come into the visible universe. They cannot leave it by definition, so over time, more and more stuff exists to us, despite all of it eventually fading to red to the point of undetectability.  There is a limit beyond which we will never see even in infinite time, and currently about 60% of that is within our visible universe, and the other 40% will move in over time. Everything else will never 'exist' in any meaningful way.

There are 100 billions of visible galaxies (reachable or not) and 100 billions of stars in our galaxy (or 400 billions but this is around this).
So let say half of the "bright points" are stars and half of them are galaxies ( galaxies and same for stars)

I think, given a good telescope, that there are far more galaxies visible than local (in our galaxy) stars. The deep field shots you see are all galaxies and no stars. The shots looking into our own galaxy find it impossible to see through the dust and other material obscuring the view. The vast majority of stars are not visible, but the galaxies are unless they happen to lie on the same plane where all the obscured stars are. I am unsure of the percentage of the deep sky that is available for unobscured viewing.

News: Earlier this year they broke the record for most distant object (called SD1), with a redshift of ~13¼, breaking the old record of about 11. The JWST did not get credit for this find. SD1 is young, small and bright, but I suspect it very much still exists (certainly as part of something bigger just like us) today.

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New Theories / Re: Can a photon escape from inside the event horizon of two black holes?

« on: 19/07/2022 20:15:32 »

But with a long line of separate singularities inside that long black hole

There's no 'long black hole'. If you put the little ones close enough together, you get one black hole, and the event horizon of it is more or less spherical (assuming minimal total angular momentum). There's no such thing as a line of barely linked black holes. I spelled out why in my prior post, which perhaps you're not bothering to read. Tell me why my explanation is wrong if it is, but don't just keep repeating refuted stuff. I lay no claim to be necessarily right on this stuff.

It isn't a normal black hole, and it isn't a normal merger of two either. In a normal merger there are two singularities inside a single event horizon

No. Per no-hair theorem, there's no external difference distinguishing one arrangement from another. Black holes have mass, charge, and angular momentum. They don't have different shapes due to internal arrangements of matter/singularities. Your entire line is in a one black hole. It cannot differ from another black hole with the same mass/momentum/charge. It cannot separate into two parts any more than a normal one.

This is something that may never have been explored.

Per above theorem, it has been explored, and proven otherwise.

[I like the list of "similar topics" underneath: Do white sheep eat more than black sheep?]

Ah, the wonders of low-AI word matching. @neilep would love the topic, and sure enough, was the first to reply.

Answer is obviously yes since there's so many more white sheep mouths to feed than the black ones.

12

New Theories / Re: Can a photon escape from inside the event horizon of two black holes?

« on: 19/07/2022 17:34:34 »

If we have two long lines of black holes running into each other (with each black hole aimed at the open spaces between black holes in the opposite line, all the event horizons would link up into one with lots of singularities within it

Doesn't work. The correct answer involves coming up with a metric describing this that is a solution to Einstein's field equations, but that is beyond either of us. But some naive reasoning may still apply.

You have a series of masses, say 1 cm radius black holes (a bit more massive than Earth each).
There's some threshold of (coordinate) separation where the line is either a series of distinct masses, or is one large mass (regardless of the number of them that you put in the line).  So we presume the separation is greater than that, so they're spaced over 2cm apart. Any less than that and the mass of any pair of adjacent ones is greater than their mutual Schwarzchild radius since the latter is directly proportional to mass (well, at least for the two of them in isolation). So any finite line of these masses will have a Schwarzchild radius greater than the length of the line, and thus it will just be one big black hole.
So they're further apart than 2 cm.  When the oncoming 2nd line of BHs comes on, for a moment they'll be one line with half the separation between them. Same story. If that new half-separation is under 2cm, both lines become one black hole and nothing gets out. If they're still further apart than that, then none of your event horizons (assuming naively that they don't distort) will overlap.
So they pass without incident. High speed of passing doesn't help. If anything, that just adds energy and makes it more likely to be that one big BH. If slow and steady doesn't work, doing it fast isn't going to help, at least not for the line scenario.

so can they really be halted quickly enough to stop them separating again?

If they're one big black hole, then there's no meaningful coordinate 'speed of halting'. It's just there. Under the presentism that you love to push, it takes nearly infinite time for the speedy objects to come to a complete halt, assuming equal speeds/masses in opposite directions. There is probably a brief but intense pulse of gravitational waves that you'd not want to be near.

If the two singularities move further apart by continuing in the direction they were moving in at the start, the depth of that photon in the gravity well will reduce and it can end up outside the event horizon.

Said photon was never inside any EH then, by definition. See my very first sentence of my first reply. You're positing this photon outrunning a null surface, which requires it to move faster than light, a self contradiction.

13

New Theories / Re: What is the real meaning of the most-distant-quasar/galaxy?

« on: 17/07/2022 12:48:30 »

Quote
Sorry, why do you claim that my assertions are wrong.

Because they predict the rapid breakup of arms

Wow!!!
You fully that our scientists "predict the rapid breakup of arms"

Halc clearly had stated that our scientists "predict the rapid breakup of arm":

predict the rapid breakup of arms

That prediction is a direct outcome from the Dark matter.

You did not answer the questions I required. You thus fail the test of being someone who displays any reading comprehension skills. For instance, this little quote above suddenly suggests that I said that scientists predict the rapid breakup of arms, when I of course made no mention of scientists (or dark matter) in what you quoted. It was your assertions that do, and thus your assertions that contradict the evidence.

Can you please explain the process how the dark matter by itself can help the spiral arms to be recovered to their nice symmetrical spiral shape after they have been broken?

Another example. Nobody every suggested this. You cannot read.

Based on the replies here, and since you would not answer the questions testing if it is worth leaving the topic open, it is (and has been for some time) very apparent that communication with you is not possible. This is a waste of everybody's time. Topic closed.

14

New Theories / Re: Can a photon escape from inside the event horizon of two black holes?

« on: 17/07/2022 03:47:06 »

There may be room for an argument about whether the event horizons join up for a moment or not in a case where the black holes don't merge and go their separate ways afterwards

No there isn't. An event horizon isn't a location in space. It's a null surface, and there's no way for two null surfaces to touch and then separate. For example, it's not possible for the future light cones of two spatially separated events can intersect and then later on not intersect.

15

New Theories / Re: Can a photon escape from inside the event horizon of two black holes?

« on: 16/07/2022 23:48:57 »

Can a photon escape from inside the event horizon of two black holes?

It wouldn't be an event horizon if it could, so no, by definition.

Picture a situation where two black holes are moving in opposite directions at just a fraction under the speed of light. Their event horizons are length contracted so much that they practically become discs rather than spheres.

You're using special relativity concepts to describe something gravitational, which isn't the way to go about it. A stress energy tensor might describe the situation. You're picturing a Schwarzschild black hole in a non-Schwarzschild situtation. That doesn't work.

The two black holes pass each other in such a way that at the point of closest approach the edges of the two discs pass through each other.

Translation, two black holes with high relative velocity and similar Schwarzschild radius r pass at perhaps less than 2r of each other (coordinate separation?). Event horizons can't 'pass through each other'. Either there could be events between them from which light could escape or the event horizons merge, and it must become one black hole.

Picture one moving towards you and the other moving away, and imagine them side by side as they pass each other - both should be deflected sideways by each other's pull, and the amount of that deflection will be related to how fast they're moving.

Yes, a plot of their mass centers will curve. There will be a sort of coordinate distance between them at closest approach, and we assume that they're far enough aprat that they don't merge. You're at that midpoint, and by symmetry, you go nowhere. You live to see the day and tell others about it, so light has escaped from you, and thus you've never been within either event horizon.

16

New Theories / Re: What is the real meaning of the most-distant-quasar/galaxy?

« on: 16/07/2022 13:00:19 »

Answer the reading comprehension questions Dave, or you fail the test of being smarter than a 3rd grader and the topic gets closed.

As both stars orbit at the same velocity

Oops

Sorry, why do you claim that my assertions are wrong.

Because they predict the rapid breakup of arms, yet most galaxies have arms. Your claims contradict evidence, but that's nothing new.

17

New Theories / Re: What is the real meaning of the most-distant-quasar/galaxy?

« on: 15/07/2022 17:35:18 »

I have also said that trying to explain something to you is about as productive as explaining it to my cat.
You display negligible reading comprehension skills, and mathematics and logic skills are also lacking.

This topic seems to be devolving into assertions of slander against these 'astonomers' that have so little clue, so I am once again threatening to close the topic that has long since passed any hope of making progress.
But let me put a little reading comprehension test, based on some past responses. Apologies for treating you like an 8 year old in a quiz here, but you're determined to act like one.

What is being violated without dark matter is basic Newtonian law. We have objects (our solar system say) that accelerate far more than can be accounted for by the sum of the forces applied by all the various baryonic masses in the galaxy. Thus there must either be more (a lot more) mass that isn't baryonic, or Newton's laws (the inverse square one concerning gravitational attraction) are wrong.

Your explanation is valid as long as we ignore the arms.

What exactly do you think I was saying in that quote?
Please don't just copy my words. Tell me in your own words what the post was about.
You don't have to agree with the words, just give an indication the comprehension isn't totally absent.
Why do you think mention of arms was necessary?
Who was the comment addressed to?
What was the purpose of my posting that when I've been mostly keeping out of this?
Was the purpose served?

You go on to reference the same comment again, like it somehow backs some assertion of yours.

There is no "arm" in [Halc's same] explanation.
In order to get better understanding, please also see the following:
https://en.wikipedia.org/wiki/Galaxy_rotation_curve
"The rotation curve of a disc galaxy (also called a velocity curve) is a plot of the orbital speeds of visible stars or gas in that galaxy versus their radial distance from that galaxy's center."

The rotation curve comment you quote also does not mention 'arms'. What do you think the wiki comment says? Why was a reference to my comment (especially my lack of mention of 'arms') relevant to this comment?

Quote from: Dave Lev on 08/07/2022 06:22:55
Please set each star at a fixed velocity and fixed orbital radius.
Based on my basic logic, while a star at 15KPC complete only one galactic cycle, a star at the same arm at 3KPC would have to set 5 orbital cycles.
So please, based on your superior logic, how many orbital cycles (for the one at 15KPC) are needed in order to break the spiral arm structure?

Here you actually make a point. Stars closer to the center go around much more often than the ones further out. The ratio of 5 is poor mathematics, but the ratio is not far from that. You're giving evidence that your assertions are wrong. Not sure why you're doing this.
As for superior logic, you commit a straw man fallacy here, asserting facts that are not held by these 'clueless' astronomers, only by you. So that's the demonstration of 'superior logic' you've been requesting.

As you think that you do understand, then please advice what is the meaning of the following message:
https://scitechdaily.com/galactic-bar-paradox-a-mysterious-and-long-standing-cosmic-conundrum-resolved-in-cosmic-dance/
"The bar in the center and the spiral arms are thought to rotate at different speeds. If they are disconnected the bar shows its true and smaller structure (left). Every time they meet, the bar appears longer and its rotation slower (right). Credit: T. Hilmi / University of Surrey"

OK, since you quoted that, what do you think it says? This is a reading comprehension test remember.
Why do you think this comment is relevant here?
The comment is a caption, and is obviously commenting on the images above it. What is it saying that you think is worthy of being introduced in this topic?


If this is too difficult, you've really no business wasting all our time on this site.

18

Physics, Astronomy & Cosmology / Re: What would happen to the Solar System's gravitational connections if ....?

« on: 14/07/2022 20:30:13 »

while, on a occasion, a comet does crash into the Sun, the newly formed Black hole would be an extremely small target to hit.

So the Sun turning into a BH would affect the orbit of a comet but not (as @Halc  says) that of the planets?

No, it would not alter the orbit of a comet or any other object. The sun squashed down to a 3 km black hole merely becomes a much smaller target, so a comet that might have hit the sun would miss the black hole.

19

Physics, Astronomy & Cosmology / Re: Has the distance between the sun & earth changed?

« on: 13/07/2022 17:06:04 »

What laws and conditions are you relying on to allow the system to lose rotational energy via radiation and not momentum via radiation to the system under consideration.

Basic Newtonian law, under which the Sun/Earth/Moon system is effectively closed with no external input of torque. It is obviously not closed to heat radiating away.
Spin momentum is transferred to orbital momentum until the relative spin ceases.

The link you give is for gravitational waves, which don't exist in Newtonian physics. It is a relativity thing, and it does indeed radiate away angular momentum, but at an incredibly small rate (200 watts of power, conversion to momentum left as exercise). This was listed as the 4th thing affecting Earth's orbit in my post 5, and it is driven by orbital energy, not spin energy.

The sun consuming its fuel also reduces the system angular momentum, just like getting a log spinning and then setting it on fire. Its RPM would be constant absent friction, but it would lose momentum as it loses mass to the combustion.

20

Physics, Astronomy & Cosmology / Re: What would happen to the Solar System's gravitational connections if ....?

« on: 11/07/2022 14:57:11 »

What if the Sun became a black hole almost  instantaneously?

It would get very cold in short order. Humanity would survive perhaps a couple months in a few places, more if they're given time to prepare for the calamity, but what would be the point of such preparation?
A nuke sub, heavily stocked and lightly crewed, would be my choice of places to last the longest.

The people on Jupiter and further out would probably not notice since local energy is far greater than the pittance given by solar radiation.

In that scenario what would happen to    the orbits of the planets?

Nothing of course. You seem to know this already.  The orbits are determined by acceleration=GM/r² and period=√(4π²r³/GM) and none of those values are changing in your scenario.