1

New Theories / Re: What is non-returning twin paradox?

« on: 28/09/2023 22:33:18 »

Twin A finds twin B as younger than himself, hence he says that B experience time dilation.

No. While in relative motion they both consider/know that time is slow for the other. That's what is called "Time dilation".

And it goes both ways - it's reciprocal. After all, that is what puts "paradox" in "twins' paradox". (But to be clear, it's not actually a paradox, there's is no argument about that. The term comes from a naive partial understanding.)

On the other hand, Twin B finds twin A as older than himself, hence he says that A experience time contraction.

That one turns out a different age than the other is usually called "differential aging".

2

Physics, Astronomy & Cosmology / Re: Does helium make all sounds higher pitched?

« on: 03/09/2023 21:08:41 »

I don't think so, Kryptid. The resonant frequency of the glass is determined by the physical properties and physical form of the glass. The larynx relies on gas properties, a bit like an organ pipe. Have look at organ pipes and how they work, with open and closed pipes influencing the frequency. There might be some slight effect with different gases.

3

Physics, Astronomy & Cosmology / Re: How do we know that particles are entangled?

« on: 27/06/2023 18:53:26 »

How do they know that the spins of each electron were not predetermined when they were entangled. 

Bells inequality.

4

Chemistry / Re: Why Choose Full Lace Remy Hair Bundles?

« on: 11/06/2023 19:50:59 »

Hmm...how did sxgrt know about the Spam Link?

Links were Removed from the OP's original message.

But when sxgrt Quoted the OP post, the Spam Link is right in there.

How's that Possible?

5

New Theories / Re: A Quandary about Accelerated Motion in Special Relativity

« on: 24/04/2023 17:01:22 »

Hi.

   OK, we can see the diagrams you ( @MikeFontenot ) have posted.    We can also see that you have drawn some diagonal lines between the two worldlines.

   So I'm going to agree with previous comments from others.   The situation is very much like Bells's spaceship paradox and it is probably best explained just by looking through a good explanation of that situation ("paradox" - although it isn't really a paradox, a perfectly fine explanation does exist).

     I'm, not sure that the link to Wikipedia's article provides a great explanation.    Try this explanation:
https://math.ucr.edu/home/baez/physics/Relativity/SR/BellSpaceships/spaceship_puzzle.html
    (That's a physics  FAQ  webpage  from the University of California and should be safe enough).
I've noticed that their diagram and explanation has the same approach of drawing diagonal lines from one worldline to another (lines of constant time or of "simultaneity" in a different frames of reference).    I think it will help to remind you of what was actually done in your own diagram and answer many of your questions.   Obviously they have chosen to put time on the y-axis and not the x-axis but other than that switch it's showing exactly the same as your diagram.   

    The phrasing of these situations is always complicated and English Language is rarely the best tool to use,  diagrams really help.   The phrasing used on their  ( ucr) webpage isn't without some problems but it's a good effort and I doubt I could do much better.     Notice that they do end the discussion with a digram showing a very different pair of worldlines the objects could have traced out in the lab frame  (the one you called IRF in your posts),  where the people in the rockets now would find that the distance between the rockets remains constant - but the person in the lab frame no longer does.

A new question: Do the two observers who are doing the accelerating agree that their separation is decreasing?

    If you manage to follow the explanation of Bell's spaceship paradox you'll see that the answer is  "no",  not if the objects have the worldlines with the shape you've given them.   The distance also doesn't decrease as you stated, they would notice the distance has increased.   

Best Wishes.

6

New Theories / Re: Biblical Flood

« on: 04/02/2023 21:11:37 »

My theory predicts PE2 particles (anti-protons) should be unstable in a positively charged universe.

Well then your model has been falsified, as antiprotons are very much real.

Since you have ignored my last post yet again, and you were warned about it, this thread is getting closed. Don't open a new thread about your model or it too will be closed and you will be suspended for trying to bypass a thread locking.

7

Physics, Astronomy & Cosmology / Re: Does time have more than one direction?

« on: 12/12/2022 04:51:25 »

Hi.

Some of the formating of quotes has gone wrong in your last post. So I'll just use something sensible here:

ES said:   How long did you take to come up with that?
Halc replied:  Quite some time ago, when first asked how to point in the 4th direction.
   The original comment was about the time axis and was sufficiently inspired it's worth repeating here:

The time dimension is like that. You pick two events (points in spacetime). You say 'this' event and clack two rocks together to define the event.  Then you wander off some arbitrary place and clack the same two rocks a 2nd time to define a second event. The one unique line through spacetime connecting those two events is now defined. You've chosen a totally arbitrary orientation for your time dimension since the two events you chose are completely arbitrary.

   
   Now, I did mention in a post some time that it was "more or less" correct.   I'm just going to discuss the "less" part here because the "more" part speaks for itself, it's an amazing way of describing how you could choose a time axis.  So, there's genuinely no offence intended.  You've obviously spent some serious time replying to @Dimensional and might just want a little feedback or something to think about.

   Let's start by considering a person, we'll call her Roxanne ("Roxy") because she's the one who will be doing the rock clacking.   Now Roxy starts by clacking some rocks at  x=0, t=0 in whatever co-ordinate system she was originally using.   Supposedly, Roxy can clack more rocks at any arbitrarily chosen event in spacetime.  Let's say she clacks the rocks at the event   x=10, t=0   in her original co-ordinate system.   So that's just two events that were at the same co-ordinate time and just lay along the x-axis of her original co-ordinate system.....   do you see where I'm going with this?
    The spacetime interval between those two events =  +100   (in a suitable convention with  ΔS² =  Δx² - c²Δt²),  in particular they are most definitely spacelike separated.  Moreover, the spacetime interval is a conserved quantity under any Poincare transformation we apply.  So whatever new co-ordinates t'  and x' we try to generate,  we will still have    ΔS² = +100 = (Δx')² - c²(Δt')² .   It's the being positive thing which is the real sting in the tail.  The two events remain spacelike separated.   In particular there is no way those two events can lie along the new t'  time axis.
   More generally, the two events with the rock clacking can't be completely arbitrarily chosen,  the first one is arbitrary.  The second one must be timelike separated.
   **Also,  Roxy is only metaphorically allowed to "wander off" to the other rock clacking event.  Since that event must be timelike separated from the other one, she has to run faster than anything else in her world.  That's not too bad though, there doesn't need to be a Roxy and even if there was she was only metaphorically wandering off to the other event.**

Best Wishes.   

**LATE EDITING:  I've already spotted that the last paragraph was backwards,  Roxy can't get to spacelike separated events but timelike is no problem.   I've left the error in because we're all human.  **

8

New Theories / Re: Gravitational Arm

« on: 16/11/2022 12:59:11 »

THANKS
So you fully confirm that one spiral arm which is connected to the other galaxy is due to gravitational attraction.

Do you fully confirm that this simulation shows that using our current theories a stream of stars between interacting galaxies is not a surprise?
https://svs.gsfc.nasa.gov/10687

9

New Theories / Re: Gravitational Arm

« on: 16/11/2022 06:05:05 »

However, once one spiral arm had been frozen by gravity force to the other galaxy

It isn't. Gravity isn't freezing anything in place here. It's like saying something in free fall is frozen in place. It's not. This tidal tail is a temporary structure.

10

New Theories / Re: An Offer I Made to Utrecht University in the Netherlands

« on: 19/10/2022 17:00:00 »

This poster has repeatedly ignored moderator requests to:
-  keeping to topic and not ranting.
- not reopen a closed thread
- post only in New Theories section

This topic has been previously published elsewhere by the op, however we cut him some slack to allow discussion and defence of his ideas, but he has now resorted to more off topic rants and has also used non-family friendly language.

He also needs to note that his maths has been commented on by @Halc who is to be commended for taking the trouble to answer a very confused piece of pseudomaths which demonstrates very poor understanding of both the maths and physics by the op.

For the above reasons this poster is now banned.

11

Physics, Astronomy & Cosmology / Re: Are fields and particles something of a chicken and egg story?

« on: 14/10/2022 00:38:02 »

Hi.

I've seen discussion of how there were not distinct fields at first, and gravity separated out first, followed by other forces/fields.

    Yes,  that's OK.   I've seen similar discussions, usually focusing on the fundamental forces and when they begin to separate as temperature and presure falls in the universe.
     I had the impression that all the fundamental forces were always there,  it's just that some were indistinguishable.    To say this another way, the original one big force was always four individual forces added together but they all behaved the same way.   So, there was in effect just the one big unified force.   This is different from saying that some forces were not there at all.  This could be a matter of semantics or personal preference but since it's a quiet day, I'm going to keep pushing the point.   

    Example:      You have a stack of  4 bricks on top of each other,   this height or the total stack is the value of the original grand unified force.   Later on the bricks cool down and you can start to see that there are differences between the bricks:  The yellow ones are water-proof,  the red ones are harder, the green ones are spongy.  That's how I imagine the situation:   All the forces were always there, you just couldn't distinguish between them.

    To put this on a more secure mathematical footing:    There should be one Lagrangian describing the system   (the whole universe),    the one commonly used for the standard model of physics as derived from QFT is shown on this t-shirt:

Lagrangian tee.png (184.14 kB . 428x411 - viewed 1380 times)
   (The details aren't important  AND indeed this is still thought to be just an approximation.  It's a low energy approximation -  a good approximation for the Lagrangian at sensible temperatures etc.)
   Note that the standard model Lagrangian is just the sum of components, where each component is usually identified as being due to ... a photon field component, Higgs components,.... etc. etc.   
     Anyway, assuming the universe can be described with a Lagrangian then there is no reason why the Lagrangian would suddenly be thrown away and a different Lagrangian used at high temperatures or pressures such as close to the time of the big bang.   However, many of the terms within each component can and do conceal expressions like   (1/T)   where   T is the temperature.   So as  T ---> hot   then these terms -->0.   The disappearance of these terms results in the properties of what was the electromagnetic field becoming indistinguishable from  those for the nuclear Weak force   etc.       Anyway,  that's my take on it.    The Lagrangian can't suddenly be a different Lagrangian at early times,  it should really be just the one Lagrangian all the time.  Just because you can't easily identify one component from another at high temperatures does not mean that they were not there,  they were just a portion or fraction of the force you can find.    (This is very informal, with many simplifications,  for example not all the interactions or forces have a simple numerical value which you can just divide up into fractions,  some interactions are described with rank n tensors instead of single numerical values).

Best Wishes.     

12

General Science / Re: Are space and time just two sides of the same coin?

« on: 03/07/2022 16:59:06 »

Might be time to take a pause and look at some basics here because I think there are some misunderstandings.

Minor point. Ideas generally come before models, but not always. Take eg of Copernicus, before him the idea was that the sun orbited the earth. The top mathematicians of the day, the Arabic scholars, struggled to find a model that worked with this idea. Copernicus came up with a different idea, that the earth orbits the sun from which a model of the planetary system could be developed.

Perhaps you're still convinced that movement needs a time dimension to facilitate it but are unwilling to stand up for your conviction. 

That depends what you mean by dimension and what you mean by facilitate.
Physics defines seven primary dimensions: length, mass, time, temperature, electric current, amount of light, and amount of matter. I suspect you would only consider one of those to be a dimension, that’s because the common usage of dimension is very different from the physics usage.
Facilitate movement? Certainly we know that any movement has a start position and time, and an end position and time (physics calls these points events and there are an infinite number of such events between start and finish). Whether you consider time to facilitate that movement is debatable, but I would say not. For example, we measure the temperature dimension, but it would be unusual to suggest that the dimension facilitates temperature. Temperature is facilitated by other causes, we just measure the effect.

The idea that there is a past, present and future is speculation when all we know is the present. I remember where objects were before they moved (past), and I can predict where objects will be after they move (future) but memory and prediction of movement is far from being evidence of a time dimension. This is a mistake and one that is rearly admitted.

I’m not sure who you think rarely admits it. I would agree if you are talking about the general population, but physicists (and philosophers) frequently debate this area. Your view is a form of temporal presentism, but there are many other options including block universe. So, you have nailed your colours to a particular wall, some would agree with you, but there are others who would say you are wrong to do so.
I tend to think in terms of a dynamic view of time. Do I believe that somewhere in spacetime Anne Boleyn is still being executed, or WWII is still being acted out, no. However, I would never be as arrogant as to say that my view is correct and all other views wrong.
@Halc has probably looked at all the different philosophies, but I suspect your accusatory tone might have put him off further discussion.

…….as long as you remember they are just imaginary.

Imaginary has a different meaning in physics to common usage. It does not equate to not real, as in unicorns are not real.

I understand you for some reason don't like that time is a dimension,

Pesky empirical evidence.

If you can devise an experiment that will provide unequivocal empirical evidence of your idea, then you will be in line for a Nobel prize. The reason there is so much debate and varying views in this area is because there is no empirical evidence.
There is, however, a lot of evidence that our common sense view of distance is affected by relative movement, and that what is the past for me might in some circumstances be the present for someone else. Distance is also affected by gravitational potential, so 2 people at different heights above the earth could disagree on vertical measurements.
Experiments in particle accelerators also tell us that distance is not what our ‘common sense’ might suggest.

I want to meet you at Joe's in 10 unicorns, of course we will have to set up a convention for one unicorn like the swing of a pendulum or the movement of the sun, however we won't need to set up a convention for the spatial dimensions because they actually exist and we can measure them directly.

As Origin points out, you are confusing units with dimensions.
Hours and unicorns are units and arrived at by convention, so are distance units.
Also, there are many things we cannot measure directly, but that doesn’t mean they don’t exist.
Interestingly there are many people who have a very good sense of time and can tell to within 15mins what time it is, and musicians have a very good time sense otherwise there would be no consistent rhythm.

All in all this is quite a complex subject, but I’m glad you are taking the time to think about it.

13

Just Chat! / Re: quick question on being timed out

« on: 09/06/2022 14:35:12 »

Hi again.

I can't take the tiny 4-8 line window they give you,

    Yes... it's like performing key-hole surgery.
However, you can make the text box bigger....

text-box.JPG (41.7 kB . 1062x293 - viewed 1887 times)

Grab that piece highlighted in yellow and drag it downwards..... 

Best Wishes.

14

General Science / Re: At what gravity does a person run the fastest?

« on: 06/04/2022 16:45:48 »

Hi.

Found this:
https://journals.biologists.com/jeb/article/221/3/jeb162024/20344/Reducing-gravity-takes-the-bounce-out-of-running

A scientific study, with actual data collected, about the running stance and gait adopted in simulated low-G environments.

Their conclusions:  Mainly that the gait is adjusted so as to keep the centre of mass extremely flat and level, i.e. almost all bounce is removed.  Their models suggest this is energy efficient (they use "an impulsive model of running" developed by Rashevsky and Bekker - although these people contributed at different times and not collaboratively).
    There is no comment or investigation about the maximum speeds attainable, sorry.  However, if this low bounce method is more energy efficient you would have thought that a runner can sustain a higher maximum speed.

Noteable limitations
   They didn't seem to have a wind fan or anything to re-create the effect of air resistance.  However, you would have thought this would only further reduce speed while in the air and unable to provide propulsion with your feet, so that it would only increase the desirability of maintaining a low bounce running style.
- - - - - - - - - -
We've already mentioned that accelerating from a standing start is a completely different thing to sustaining a high top speed.   Just for amusement, here is Usain Bolt trying to sprint in low G:

Best Wishes.

15

Just Chat! / Re: Here is Practical Explanation about Next Life, Purpose of Human Life,

« on: 18/03/2022 15:55:26 »

It was nonsense last time, and it hasn't got better
https://www.thenakedscientists.com/forum/index.php?topic=75636.msg561835#msg561835

16

Physics, Astronomy & Cosmology / Re: Why don't gamma rays have a higher speed?

« on: 20/02/2022 07:47:01 »

the speed of electromagnetic propagation is based on experimental observation of the relationship between electric and magnetic fields

Maxwell's equations were a brilliant synthesis of everything known about electric and magnetic fields, producing a surprisingly accurate prediction for what we now call "c"
- I understand it was the agreement of the experimentally measured speed of light with the prediction of Maxwell's equations that influenced some people to think that light had to be electromagnetic waves.

However, Maxwell's equations do not explain why hypothetical gravitons (or the more classical gravitational waves) should also travel at "c".
- So far as we know, oscillating electric or magnetic fields do not generate gravitational waves, but do generate electromagnetic waves
- So far as we know, oscillating masses do not generate electromagnetic waves, but do generate gravitational waves (provided the masses are electrically neutral)
- And yet Einstein predicted that both would travel at "c"
- And observations of colliding neutron stars suggest that they travel at identical speeds (within very tight limits)

why does the frequency increase instead of a compromise between frequency and speed?

"c" is the velocity of light in a vacuum.
- However, in materials (eg water or optical fiber), there is a change in speed with wavelength, which is called "dispersion"
- This produces the familiar rainbow
- From Wikipedia: For red light (wavelength 750nm, η = 1.330 based on the dispersion relation of water), the radius angle is 42.5°; for blue light (wavelength 350nm, η = 1.343), the radius angle is 40.6°.
Since the refractive index η = c/v, the higher refractive index of blue light implies that its velocity is slightly lower than red light, when traveling through water. The questioner assumes that higher frequency would produce a higher velocity.

https://en.wikipedia.org/wiki/Rainbow#Mathematical_derivation

Oops - overlap with Colin2B

17

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

« on: 23/01/2022 23:42:32 »

Im the one that asked the question; and thank you for posting this Origin.

I would like to know if this distance is a big cause of Climate change.

I see from posts that the distance does change, though is there an on going change that is climbing (a distance change or orbit change), and not staying nominal?

It can have an effect to some extent, and there are some cyclical changes in earth's orbit (see more here: https://www.fs.usda.gov/ccrc/education/climate-primer/natural-climate-cycles)

But the current (fast) changes in the climate are driven primarily by greenhouse gases (mostly carbon dioxide and methane).

We can see the effects of the cycles, as well as the recent trends (the practically vertical line at the far right) by looking at atmospheric carbon dioxide concentrations found in ice cores, the record of which goes back almost a million years (https://keelingcurve.ucsd.edu/)

co2_800k.png (110.13 kB . 1000x600 - viewed 9767 times)

18

New Theories / Re: Density Wave - Is it real?

« on: 08/12/2021 18:11:59 »

https://www.astro.princeton.edu/~eco/research/spurs/project.html

19

Question of the Week / Re: QotW - 21.10.18 - Is Dark Matter lumpy or like grains of sand?

« on: 24/10/2021 05:15:04 »

Hi,

    Ps - Mass causes Gravity, so does Momentum.
    (Equivalence)

[citation needed]
I actually googled this and got fantastic list of sites pushing bad science, but nothing that supports this.

Let's help Zer0 out a bit here.  (You don't need any help @Halc , you already know your stuff and should be confident enough already).

I think Zer0 was talking about this kind of thing:
    https://en.wikipedia.org/wiki/Stress%E2%80%93energy_tensor
The stress-energy tensor takes mass, energy and momentum as it's components.

[Diagram from Wikipedia.  See earlier link]

   Over half of the stress-energy tensor could be considered as something derived from 3-momentum and all of it is if you're considering 4-momentum.

Here's a quote from Wiki:
     The stress–energy tensor, sometimes called the stress–energy–momentum tensor or the energy–momentum tensor, is a tensor physical quantity that describes the density and flux of energy and momentum in spacetime,........... This density and flux of energy and momentum are the sources of the gravitational field in the Einstein field equations of general relativity, just as mass density is the source of such a field in Newtonian gravity.

    However, it's a bit of jump to claim that momentum is equivalent to mass.  (I mean, it just isn't in the wider sense of it but let's just confine our attention to gravitation for the moment).      Even as regards being a source of gravitation or curvature for spacetime there are limits on our ability to exchange momentum for rest mass.  The momentum of objects in space does influence the curvature of spacetime but not in the same way as rest mass would:   Just by looking at the stress-energy tensor we can see that rest mass will contribute to the  0,0  (or time-time) component of the stress energy tensor while 3-momentum contributes to other components.  So there are going to be some solutions to the Einstein Field Equations (some manifolds and metrics) for spacetime that can't be re-created by trading rest mass for momentum.  (This is not a trivial or obvious fact.   It's obvious that the solutions will be different but less clear if there would be a change of co-ordinates which make the solutions physically equivalent - i.e. the metric solutions are just tensor transformations of each other).
    I can't really be bothered to check if it might be possible to identify the different solutions you obtain as being equivalent but in different co-ordinates but I don't think we need to.  The following example seems sufficient to show one situation where we could not hope to find such a transformation.
   
    Brief example with diagrams    Consider space that is empty apart from 3 particles that are initially at rest in a line    •   •   •     That should provide us with a certain metric as a solution to Einsteins Firled Equations.  The particles will move in response to this curvature but we can see that their movement will effectively bring them together and in the natural co-ordinates in which we are regarding the situation, the centre particle never moves and we will be able to identify an event in spacetime where all the particles collide.
   Now we could reduce the mass of the centre particle  to get    •    ^•    •        and we could try and give the centre particle some momentum, possibly enough to compensate for the reduction in mass.  This may give use the same solution for the metric initially but it will only last for one instant, since the centre particle was given a non-zero momentum initially it must move relative to the other two particles and the curvature of space will change in response.  Depending on how much momentum the centre particle has and the initial direction of that momentum we can obtain drastically different results as time evolves.  For example the centre particle may come into contact with one of the particles before the other (and not both simultaneously) or it may be travelling off at some angle to the line of particles with sufficient momentum that it will escape to infinity and never coalesce with either of the big particles.  These are events in spacetime where only 2 out of the 3 particles will occupy the same space at the same time.   I can't see any way in which a change of co-ordinates would be sufficient to make the metric or the curvature of spacetime in this situation equivalent to the metric in the previous situation - but let's go slow and check it a bit more....
     The events we can identify in spacetime are fundamentally different and no change of co-ordinates can map events from one situation to events that don't exist in the second situation.  As compelling as that seems, it's not quite enough to be certain that the curvatures of spacetime won't remain the same.  All we know is that our overall systems must be physically different and not just co-ordinate transformations of each other.  The geography of the landscape might be the same even though we had different collisions between vehicles driving over the landscape - we knew the vehicles were different in mass and momentum initially anyway.  We do need to check carefully that the geography of the landscape must be different.  Since there are some significantly different events (such as when and which particles collide or occupy the same space) we can drop in a test mass at key times and see that it's movement differs   (for example if all the particles have coalesced, as in the first situation, then regardless of where you drop the test mass in, it can only be attracted to one point in space but this is not true if you're in the second situation and only 2 out of 3 particles have coalesced).  From the different movement of test particles we really can conclude that, at least at some time, the curvatures of the manifolds will be physically different and not just co-ordinate transformations of each other.

   In summary:  Mass and momentum are both sources of gravitation.  However, they are not quite equivalent, there are limits on our ability to exchange some rest mass for momentum and retain the same curvature of spacetime.  At best, we could initially obtain a space with the same physical curvature but in most situations this would not be sustained as time evolves.

Best Wishes.

(Final thoughts:  The example has turned out to be longer than I expected and perhaps I should have just gone straight for the Maths but nevermind.... most people prefer some waffle to mathematics).

20

New Theories / Re: On Kepler Orbitals For Atomic Physics

« on: 21/08/2021 23:16:08 »

The posting of this topic contravenes forum rules and has been locked