1

New Theories / Re: How black hole really works

« on: 24/04/2023 16:29:45 »

Dave, you are quite obviously arguing that black holes make their own accretion disks. You might not be saying it directly, but you are saying it indirectly. If you're arguing that matter isn't coming from outside, then you are arguing for the opposite: that it's coming from the black hole. That's Theory D. This thread is taking basically the same path as if you were talking about it explicitly. I see that you are still trying to weasel your way around a thread closure. For that reason, this thread is getting closed as well.

2

General Science / Re: [Asking ChatGPT] Could newborn childs now learn perfect pitch while they sleep?

« on: 12/04/2023 18:13:39 »

Did you know that you can ask chat bots stupid questions without telling us about it?

3

New Theories / Re: Gravity as a unity force

« on: 06/04/2023 19:30:35 »

Hi.

   Well, I thought I'd try this approach.   Some of what you ( @Yahya A.Sharif  ) have said was correct.

Spacetime does not need to be and is not defined as if it is some thing with physcal properties so that you could touch it, see it or move it.    However, PopSci articles do often provide diagrams and sketches where spacetime is thought of as if it was some sort of fabric.   The idea of it being a fabric is just a visual aid.  So it's not entirely your fault to think that it was required to be some physical thing that can be curved.

So this section:

it has dimensions but this is only geometry

   is correct.    Spacetime is just a mathematical tool or structure that allows us to specify the location of an event:
( 1, 2, 3, 4 )    is an event in spacetime which is located at  x=1, y=2, z=3 and time, t =4.

 The next section:

and there is not anything whatsoever to be curved

  is then also correct.   There may not be any physical thing there.    The term "curvature" and the notion of a spacetime being curved developed for historical reasons only.    It does not mean that there is some physical thing there which is curved.
    "Curvature" is just a technical term that has a precise meaning.   We just want to know about the distance between an event  ( 1,2,3,4 ) and some other event like  (0,1,2,3).     If that distance follows conventional Euclidean geometry then we say the spacetime is flat.   Euclid was an ancient Greek who developed most of the ideas of geometry,  you may not have been told that the geometry you studied at school was "Euclidean" but it was.   So to paraphrase the whole thing:   If the geometry we learnt at school works, then that spacetime is said to be "flat".
    (Actually, some people would prefer to say that 4-dimensional spacetime follows  Minkowski geometry but we don't really need to worry too much about the fine details).

   On the other hand, if the distance between two events did not follow the behaviour of Euclidean geometry then we say that the spacetime was curved.     That is all that "curvature" means - it just tells you if distances between two events behave exactly as in Euclidean geometry, or not.

   Now, if we examine the history then we can see why the term  "curvature" was used.    The first mathematician to study some useful geometry  (usefull for developing General Relativity) was Riemann.    I'm going to take some liberties here and greatly distort what he really did - but hopefully it will be easier to understand this way.    This is what he did:
      He imagined you had some small creatures,  perhaps ants, and all they can do is crawl over the surface of some solid object.  So the critical assumption is that the ants only know about 2-dimensions,  they are completely unaware that their world actually exists in 3-dimensions.  They cannot go straight up or straight down so as to go through or come off the surface.   The only directions they can travel in are directions they may refer to as the the x-axis and the y-axis,   there is no  z-axis direction they can move in or are aware of.
     Now, let's say that the object they are crawling over was a large and completely flat sheet of paper.    Provided the paper is flat, they will have distances that make sense and follow Euclidean geometry perfectly.   However if someone comes along and bends the paper so as to make a rounded hill in one place which is quite steep on average, then some things start to go wrong.   The ants realise that the shortest distance between two points that are on opposite sides of that hill do not seem to be a straight line.   If they tried to go straight from point A to point B that may take them over the hill.  If the hill is steep, then they have travelled a long way up in the z-axis direction and also a long way down on the other side BUT they are completely unaware that such a z-axis direction exists.  All they know is that going straight from point A to point B is a long distance they have to move.   However, if they take a curved path, then the distance does not need to be so large.   Out here in the 3-D world, we can see why - the ants have gone around the hill instead of going over the top of it.    However, all the ants know is that going in this curved path does seem to be a shorter distance between points A and points B  instead of trying to go in a straight line.   Euclid was wrong - the shortest distance is not a straight line.
      Now, we have enough to see why this sort of weird or strange geometry has been referred to as "curvature".   Riemann was studying situations where Eucldiean geometry went wrong because a surface was literally curved.   However, the term "curvature" is now just a technical term which means that distances don't follow a Euclidean form and that is all.

   I hope that helps a bit.

Best Wishes.

4

New Theories / Re: New theory of social evolution and social structure

« on: 03/02/2023 08:37:13 »

However, I invite you to read the whole thing

If the synopsis peaks my curiosity I will, otherwise I don't think so.

If I point out that the word is "piques" then this thread will serve some tiny purpose.

5

New Theories / Re: Biblical Flood

« on: 23/01/2023 13:07:38 »

https://onlinephilosophyclub.com/forums/viewtopic.php?f=12&t=15652
That page just shows that you are consistent, not that you are right.
I note he has removed the post....

I did not remove my post. Who removed my post ?

Probably somebody who realised it was pointless obfuscation.

http://www.rationalskepticism.org/pseudoscience/experiment-to-test-w-mg-t55108.html

I think the rules have something to say about posting here to drive traffic to other sites.
If you think you made a valid point at some other forum, just make the same point here.
We don't need to look through dozens of people telling you why you are wrong.
We already know that.

6

Physics, Astronomy & Cosmology / Re: What is the exact cause of the time dilation of the twin?

« on: 15/01/2023 16:19:16 »

It's not a function of acceleration, so I cannot say from just that.

Then would you say that Sabine in the video is wrong?

I am actually going to go so far as to say exactly that. I caution against taking a simple comment out of context, and I'm not much on clicking videos and actually watching them (21 minutes to wade through), and it's Sabine, so I presumed the content is accurate. Well it isn't, which is a shame.

At 0:40 she complains about trying to learn relativity from pop-science sources and failing or finding them incorrect. Many are. Here she is creating her own pop-science tutorial and she does the same thing: get it wrong.

At 1:45 she gets into the length of the path between two sets of coordinates, correctly pointing out that different paths are different lengths despite the beginning and end of the paths being the same, as it is in the twins scenario.

At 6:50 she shows how the calculation of the temporal length of an arbitrary path can be done by breaking the path into pieces and integrating over the length of the path. This is what Eternal Student has done in post 16:

Do you know any math formulas to see how acceleration and time dilation are related?

the elapsed time for the travelling twin (who goes to Andromeda) is given by:

Δτ =   

[Eqn 2]

The computation above is completely scalar. Note the complete lack of acceleration reference in the formula. I see time and speed (v) and that's it. It isn't a function of acceleration, as I said above. The formula above is from special relativity, so it only applies to the special case where gravity is not involved. Hossenfelder's video is entitled "Special Relativity: This Is Why You Misunderstand It", which means the content should stay away from gravity, or the video is mistitled.

And what's with Andromeda? Sure, with enough acceleration, Bob can get there and back before he dies, but Alice (and the whole human race for that matter) isn't going to be there upon his return. Sabine should pick a closer target.

Back to the video:
At 11:00 we get into the twins thing and she correctly says that at least one of the twins needs to accelerate to turn around. That's a biased way of putting it, but true. More correctly, at least one of them needs to accelerate in order for their paths to diverge but meet up a second time. Without acceleration, any relative velocity will just have them meet once at best and forever diverge after that. But it isn't the acceleration that causes the dilation, it is the relative temporal lengths of the paths they take, as computed by the above formula.

11:25 She says acceleration is absolute. She means proper acceleration (the kind you feel with an accelerometer) is absolute. Coordinate acceleration is relative to some coordinate system and is thus not absolute. So sitting at your computer reading this, your coordinate acceleration (relative to your house maybe) is stationary, but your proper acceleration is 1g upward because that's how hard the chair under you is accelerating you.

12:52 She correctly points out that the twins scenario has nothing to do with gravity.

13:39 She correctly points out that the twins starting and ending with the same velocity is not necessary (except to explain that they're twins and presumably had reasonably identical velocity at birth. They merely have to meet twice.

15:30 We start getting into gravity, which is out of scope for a video entitled "Special relativity". She starts with pointing out that under Einstein, gravity is not a force. It is in fact spacetime which has a geometery other than flat Minkowskian spacetime. So anything not accelerating (has no force acting on it) follows a geodesic along the local spacetime.

16:55 She first says acceleration causes time dilation. This is blatantly wrong. Contradictions follow.
17:50 Things really start falling apart. The time runs slower at sea level than on a mountain due to greater acceleration at sea level. This is completely wrong. If true, clocks would run fastest at the center of Earth where acceleration would be zero, but they in fact run slowest there than anywhere else on Earth. The acceleration on the surface of Mercury is under 40% of that on Earth, but time on Mercury runs slower, directly contradicting what Sabine is saying.

19:25 She asks if her video was any better than those incomprehensible books from way back? Well it would be if she hadn't mucked it up.

Back to Special relativity, since I want to disassemble her treatment of that as well and not just her botching the gravity bit. A couple examples contradicting her assertions:

Example 1) Alice, Bob and Chuck are triplets and age 20. Alice stays home. Bob and Check set out on a trip and accelerate identically (10g say) for a month and then coast, riding side by side for a while.  After a year on his own clock, Bob accelerates towards Earth at 10g for 2 months, going back towards home at the same speed he went out. He coasts for another year and takes a month to stop. He's aged 2 years coasting and 4 months acceleration and is age 22y4m now and finds Alice at age 23y2m, or 10 months older. They wait together for Chuck to come back.
Chuck coasts twice as long and turns back. So he ages 4 years coasting and the 4 months accelerating and comes home at age 24y4m finding Alice to be 25y5.7m and Bob to be 24y7.7m.
This contradicts what Hossenfelder says since both Bob and Chuck have experienced identical accelerations, just at different times. They should be aged identically per Hossenfelder's words, but they're not. This is one trouble with doing physics in the language of laymen instead of the language of physcs. Time dilation is not a function of acceleration and there's no mathematical formula expressing it in terms of acceleration.

Example 2)
I have a pair of wheels or gears. One wheel is 1000 times the radius of the other, and they meet at one point and move at the same velocity there. I put a clock on each wheel at the point at which they meet. The wheels get turned with the small  one going around at 1000 times the RPM and hence 1000 times the centripetal acceleration. Both clocks are moving at the same speed relative to the inertial frame of the setup. The two clocks will stay in sync indefinitely despite the one acceleration being a thousand times the other. This also contradicts what Hossenfelder says in the video, but is entirely consistent with the formula that ES provided.

7

Physics, Astronomy & Cosmology / Re: Has the speed of light been tested in a vacuum?

« on: 05/01/2023 20:38:30 »

Has the speed of light been tested in a vacuum?

When it comes to the speed of light, air at sea level is a pretty good vacuum.

Light slows down in a medium, compared to its speed in a vacuum
- For example, in glass, light is slowed by a factor of about 1.5
- In air at sea level, light is slowed by a factor of 1.0003
- The amount of slowing is measured by the "Refractive Index"
- See the Refractive Index list at: https://en.wikipedia.org/wiki/List_of_refractive_indices#List

For non-magnetic materials, you can calculate the amount of slowing from the measured relative permittivity of the medium.
- For air at sea level, the relative permittivity is already close to 1 (almost the same as a vacuum)
- For achievable vacuums (eg at LHC), the relative permittivity is immeasurably close to 1
- See the list at https://en.wikipedia.org/wiki/Relative_permittivity

From a totally different viewpoint, gravitational waves also travel at "c" (commonly called "the speed of light in a vacuum", but its more fundamental than that).
- Gravitational waves travel almost unaffected through the high density of the Earth, the Sun and neutron stars
- The LIGO observatory observed a neutron star merger, which was accompanied by a gamma-ray burst starting 1.7 seconds later. The source was in a galaxy 130 million light years away.
- This suggests that light travels at a speed through intergalactic space at a speed that is reduced by at most 1.7 seconds in 130 million years, ie pretty much the speed of light in a vacuum.
- See description at: https://en.wikipedia.org/wiki/Neutron_star_merger#Observed_mergers

8

Physics, Astronomy & Cosmology / Re: Orbiting or descending into the black hole at the centre of the Milky Way?

« on: 27/11/2022 20:49:35 »

Mainly the MW is in orbit around itself.

And the mass of the Milky way is dominated by the (so far) invisible Dark Matter halo.

it looks like the stars are swirling down into the black hole

Out in the fringes (where we live), the stars are well-separated, most of the stars are in a fairly thin disk, have fairly circular orbits, and and have roughly the same angular velocity. So they won't interact very strongly with each other.

However, in the central bulge, stars are closely spaced, they have wildly different orbital planes, and the ones we can see near the central black hole have rather elliptical orbits, so the stars will transfer angular momentum between each other.

Some of these gravitational interactions will "cancel" angular momentum (if the stars have different orbital axes).
I expect that this will result in the central bulge flattening out over time - but the average distance from the central black hole will then be less than it is now. When stars are moving in a disk, they will have fairly stable orbits.

...that is, until the central black hole merges with another black hole; the incoming black hole will add angular momentum into the system on an entirely different axis, and once again send the stars off in all directions.
https://en.wikipedia.org/wiki/Sagittarius_A*_cluster

it looks like the stars are swirling down into the black hole

You inferred this from looking at a still image, and imagining the galaxy as a drain emptying in a whirlpool. This is not what "Whirlpool Galaxy" means.
https://www.nasa.gov/feature/goddard/2017/messier-51-the-whirlpool-galaxy

The Gaia space probe has been able to measure the velocity of stars in the Large Magellanic Cloud, and it is showing the stretching associated with being spaghettified by its close approach to the Milky Way. But the orbits are still roughly elliptical, rather than converging on the central black hole (if it has one...)
https://www.esa.int/ESA_Multimedia/Images/2018/04/Rotation_of_the_Large_Magellanic_Cloud#.Y4PLHulNzqU.link

9

Physics, Astronomy & Cosmology / Re: Orbiting or descending into the black hole at the centre of the Milky Way?

« on: 27/11/2022 17:55:10 »

The black hole has a mass of about 4.154±0.014 million solar masses.
The milky way has something like  100 thousand million stars
So, if the sun is a "typical" star only about 1 in 25000 of the mass of the milky way  is due to the BH in the middle.
If that BH disappeared it wouldn't make much difference to the motion of the sun.
Mainly the MW is in orbit around itself.

10

New Theories / Re: Why does Mass/Energy Distort Spacetime?

« on: 21/10/2022 22:12:07 »

Then you define it by its affects. You can't pull that definition back to mass/energy itself. In itself it is vague.

I don’t know what you mean by “Then you define it by its affects”. If you mean by its effects, then yes, that is science.
We observe and define everything by the effects they have.

Your ‘theory’ is wandering aimlessly all over the place. You have 48hrs to fulfil the requirement I outlined earlier “You have to show that your idea makes predictions that are correct, as determined by experiment, and which are not predicted by any other theory.”
Failure to do this means you will be considered to be trolling us and you will be removed from the forum.

11

New Theories / Re: Can we use spheres with 2^n to show will to move (perpetual energy creation?)

« on: 17/10/2022 20:52:59 »

he said one system is aloud.

I don't think you understood me. Perpetual motion that doesn't create energy is allowed because it doesn't violate conservation of energy and therefore doesn't violate Noether's theorem.

and the mindset, is that it is proven.

It is.

its proven in instances tried.

That's the great thing about proofs in math: it's proven to be true in all circumstances already. You don't think that the Pythagorean theorem was proven by testing every possible number in the equation, do you? That would be impossible, since there are an infinite number of numbers. So we know for a mathematical certainty that conservation of energy holds in all circumstances where time symmetry also holds. If you want to beat conservation of energy, you also need to beat time symmetry.

This happens in the real world due to the metric expansion of space. This causes radiation in the universe to be redshifted, reducing the energy content of each photon. The energy doesn't actually go anywhere, it's just plain gone. This is allowed because time symmetry is violated: space now is not the same as space later (it's bigger). So that's a real life occasion where time symmetry is violated and thus Noether's theorem doesn't hold.

12

General Science / Re: Why can't radio waves pass through the ionosphere, but a spaceship can?

« on: 05/08/2022 20:02:37 »

The clue is in the name - ionosphere. Ionised air is an electrical  conductor and acts to some extent as a "short circuit" to electromagnetic radiation, but to a solid object it is just "thin air".

Obviously most em radiation does pass through the ionosphere (hence sunlight, radiotelescopes, and communication with spacecraft) but at some frequencies and angles of incidence it acts like a mirror.

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

That CAN'T be true! / Re: does tourmaline have magical beneficial powers?

« on: 24/06/2022 15:04:34 »

Oh, it keeps like vampires and werewolves away.  Does it also work on dementors?

It certainly works on spammers, this one went very quickly 

15

Just Chat! / To answer a question from Pseudoscience-is-malarkey

« on: 11/06/2022 12:58:47 »

I notice one of the other moderators has removed your post, so I’ll answer your question here

Why do we have to be subjected to such juvenile garbage on a science site???

It's the "Just Chat" section of a science sight. Anything goes, as the description pretty much states.

No, anything does not go.
We give more leeway in this section than others so it doesn’t need to be science. However, it does need to be family friendly.

Also, I do for some levity.

Levity is one thing, but you often use this section for posts in bad taste and/or of a sexual or crude nature. That’s not what this section (or any other) is for.

16

Physics, Astronomy & Cosmology / Re: Is there a net heat exchange between water and ice at 0 degree C?

« on: 08/06/2022 18:01:01 »

The average of n samples of x is ( x_i)/n. At least it was when I was alive, but this thread seems to be some kind of scientific purgatory.

17

Physics, Astronomy & Cosmology / Re: Is this a paradox in general relativity?

« on: 24/05/2022 23:15:26 »

Hi.

Is your origin (0,0) at the very back of the back fin of the ship like in the video?

  Yes.  The origin is intended to be exactly where they placed it in the original video (although I only sketched it, I didn't get a ruler and compass).
   The planet based observer says the back of the fin is at x= 0 when t =0.        Spaceman says the back of the fin is at x'=0 when t' =0.   

- - - - - - - - - -
   Just to emphasize one issue,  although in my diagrams it looks like the x and x' co-ordinates of the rock collision event are both  +5,   they aren't actually exactly the same.   That's just that the diagram is only a sketch and I haven't placed all the gridlines exactly the same space apart etc.   I just want to dispel the notion that there was any reason why they had to agree on the spatial location of the event... there isn't.

    I've run the precise calculation with these figures  (they are roughly what was used in the video).
Set  the velocity of the rocket =  half the speed of light.     
Use units for measuring time and distance so that the speed of light, c = 1  in those units   (Just to be clear that's not going to be seconds and metres.  It's just conventional to set c = 1).
Set the rock collision event to co-ordinates   (x, t) = ( +5.00 , +1.00 )   as was shown in my diagram for the planetary observer.
This becomes  (x', t') =  ( +5.20  ,   -1.73) in the spacemans co-ordinate system.
So, with these figures,   the spaceman and planet based observer disagree on the both the location and time of the collision event.

Best Wishes.

Yeah this makes sense to me.  Thank a lot.

18

New Theories / Re: Insulin myths and the science that broke through

« on: 18/05/2022 16:46:36 »

I can't answer your questions, it's 50 years since I studied chem/biochem and I never worked in this field. I am just stating that insulin can cause rapid passage of glucose into cells(not specifying which type) leading to life threatening hypoglycaemia. The point being that insulin is a direct stimulant of glucose transport-if it was just a glucagon antagonist this effect would not happen.

19

Physics, Astronomy & Cosmology / Re: Is this a paradox in general relativity?

« on: 16/05/2022 02:51:37 »

Hi.

Is your origin (0,0) at the very back of the back fin of the ship like in the video?

  Yes.  The origin is intended to be exactly where they placed it in the original video (although I only sketched it, I didn't get a ruler and compass).
   The planet based observer says the back of the fin is at x= 0 when t =0.        Spaceman says the back of the fin is at x'=0 when t' =0.   

- - - - - - - - - -
   Just to emphasize one issue,  although in my diagrams it looks like the x and x' co-ordinates of the rock collision event are both  +5,   they aren't actually exactly the same.   That's just that the diagram is only a sketch and I haven't placed all the gridlines exactly the same space apart etc.   I just want to dispel the notion that there was any reason why they had to agree on the spatial location of the event... there isn't.

    I've run the precise calculation with these figures  (they are roughly what was used in the video).
Set  the velocity of the rocket =  half the speed of light.     
Use units for measuring time and distance so that the speed of light, c = 1  in those units   (Just to be clear that's not going to be seconds and metres.  It's just conventional to set c = 1).
Set the rock collision event to co-ordinates   (x, t) = ( +5.00 , +1.00 )   as was shown in my diagram for the planetary observer.
This becomes  (x', t') =  ( +5.20  ,   -1.73) in the spacemans co-ordinate system.
So, with these figures,   the spaceman and planet based observer disagree on the both the location and time of the collision event.

Best Wishes.

20

Physiology & Medicine / Re: Is sex better in the morning or evening?

« on: 24/03/2022 17:01:58 »

Dear Sir/madam,

This is just awful.
   Other forums would have removed the thread or moved it to their "Just Chat" or "Just Offensive" section.

   If you're going to answer a question like this, then sure you can have some humour but you should do it in the general background of discussing science.
     There are nocturnal / diurnal hormone flucations, there can be better times of the day for fertility.  There may be psychological effects etc. etc.

Yours faithfully,
   Disgusted of the British Isles.
(Not that it matters - but I'm also going to boycott this forum for a day and use Science Forums instead).