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Physics, Astronomy & Cosmology / how do you differ excitons, phonons and solitons?

« on: 02/07/2020 12:26:37 »

Keep it as simple as possible please.

As a example: https://physics.stackexchange.com/questions/285083/what-is-the-definition-of-soliton
And https://www.sciencedirect.com/science/article/abs/pii/0960077994900329
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If you look at the second source they seem to mix into each other, and that's what I'm curios about.

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Physics, Astronomy & Cosmology / Why would the universe expansion slow down depending on mass density?

« on: 01/07/2020 09:43:21 »

I'll cite this "  if the density exceeds a certain critical value, the gravitational pull of each mass on every other mass will slow down the expansion of the universe "

My own take is that the gravitational pull should decrease with distance. Even though it is defined as infinite you should be able to assume that with a infinite distance between suns etc the 'space' between them becomes 'flat'.

so how did we reach this conclusion?
If you know the history of it it's even better, because I've searched for it without finding it.
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the question comes from a argument in where a expansion should slow down, to finally reverse and contract, due to the mass density becoming diluted (suns etc, more spread out inside a universe) which I sincerely doubt. Mass/energy bends space, the other way to describe it as in a Big Bang being close to a critical point, in where nothing can expand due to too much energy inside a confinement, makes a lot more sense to me. That one should be able to connect to the Schwarzschild radius, defining a black hole too.
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Hmm, rereading myself I see that it can be understood as I'm asking about what I thought of as the main stream history. But the question is about the one in where this mass density spreading out, at some critical point, leading to a contraction.

( And I saw it, will not say where, expressed by a physicist, one that usually makes a lot of sense.. Which actually made me assume that this was accepted main stream science that everyone except me knew about, which lead me to formulate this question the way I did  :)

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Physics, Astronomy & Cosmology / Can a accelerating expansion nullify gravity?

« on: 23/04/2020 20:36:36 »

Think of two galaxies separating through the accelerating expansion. At some point the light not only should be redshifted into oblivion, it should also find itself without any possibility of ever reaching the other side, becoming a sort of 'event horizon'.

so what about gravity?

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Physics, Astronomy & Cosmology / Is this question answered?

« on: 31/03/2020 21:15:07 »

 So we all know about there existing different infinities, the smaller ones and those that are of a greater magnitude.

So, as a magic trick. I take this greater infinity and try to push it into the smaller.
I know, I may have to cuddle and prod it a little. Those infinity's are not always temperate.

But, will it fit?
And how much room is left, if I can get it in?

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Physics, Astronomy & Cosmology / What is a Spin

« on: 10/08/2019 16:58:22 »

We all know that if you would translate the spin of a electron to a 'spinning top' then it would have to spin faster than light, which is a limit for anythings speed. Then we come to this  " In the not-so-recent past we delved into some of the nitty-gritty of vector bosons such as the force particles of the Standard Model. We saw that relativity forces us to describe these particles with four-component mathematical objects. But alas, such objects are redundant because they encode more polarization states than are physically present. For example, a photon can’t spin in the direction of motion (longitudinal polarization) since this would mean part of the field is traveling faster than the speed of light. "  https://motls.blogspot.com/2011/10/who-ate-higgs.html

Isn't that argument flawed? That  ' a photon can’t spin in the direction of motion (longitudinal polarization) since this would mean part of the field is traveling faster than the speed of light. '

I agree to that a 'spin' can't be ftl, but I find it harder to agree to that a quantum mechanical spin can't take any 'direction/polarization' it want. As this argument seems to state. A quantum mechanical spin has no classical counterpart, as far as I know?

Actually I've been wondering about that before too.

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New Theories / stuff I wonder about

« on: 05/07/2019 15:49:24 »

Anyone ever thought about how Einstein defined relative motion?

If you accept that a relative motion is without 'resistance' it shouldn't matter if you from your frame define a binary system 'accelerating' creating a gravitational wave. They don't accelerate, they are following a geodesic 'path' without resistance. Always in a uniform motion as far as I get it? Just like ball thrown up following its geodesic.

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Physics, Astronomy & Cosmology / How does gravity exert its influence infinitely?. Times two

« on: 02/06/2019 19:23:57 »

" f space-time is infinite ,how gravity extends to infinity?
 we know infinity is unreachable because it continues forever and no-one reach a finite point.How gravity extends to infinite distances while  infinity is unreachable? how gravity bends and curve space-time everywhere while space time end is unreachable? for gravity to bend space-time everywhere it should reach its end , how gravity bends space-time end while this end is unreachable? " By  Yahya A.Sharif

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Physics, Astronomy & Cosmology / when balls bounce from trains, do they speed?

« on: 10/01/2019 17:00:46 »

This one is fun.

" Imagine standing on a train platform, and throwing a ball at 30 km/h toward a train approaching at 50 km/h. The driver of the train sees the ball approaching at 80 km/h and then departing at 80 km/h after the ball bounces elastically off the front of the train. Because of the train's motion, however, that departure is at 130 km/h relative to the train platform; the ball has added twice the train's velocity to its own.  "
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Is it right, or wrong?

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Physics, Astronomy & Cosmology / Negative Energy is here? There? Where???

« on: 10/01/2019 16:42:22 »

Hope you like this one.

" Astrophysicists Alexei Filippenko at the University of California, Berkeley and Jay Pasachoff at Williams College explain gravity's negative energy by way of example in their essay, "A Universe From Nothing": "If you drop a ball from rest (defined to be a state of zero energy), it gains energy of motion (kinetic energy) as it falls. But this gain is exactly balanced by a larger negative gravitational energy as it comes closer to Earth’s center, so the sum of the two energies remains zero." "

Aha, 'zero'

At the center of a perfect sphere of a perfectly distributed density too?
what do you think?

( There the ball will be weightless as far as I get, so how does this work? :)

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Physics, Astronomy & Cosmology / how do objects heat up in a vacuum? aka black holes

« on: 09/01/2019 12:02:50 »

Read this " http://curious.astro.cornell.edu/disclaimer/86-the-universe/black-holes-and-quasars/general-questions/436-what-type-of-energy-does-a-black-hole-have-intermediate " where it is stated that "  These objects can gain energy from the black hole, as they fall into the potential well they heat up and radiate (often in the X-ray region of the spectrum). " ?

that they do it falling from space here on Earth is due to friction, but a mass following a geodesic in a vacuum?
Why would they 'heat up'?
Tidal forces?

Can't  be the Unruh effect

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Physics, Astronomy & Cosmology / Why doesn't a duck's quack echo?

« on: 05/11/2018 17:56:56 »

Saw it on the telly today, given as a fun fact?

(waiting for the doctor:)

Is it true? If so, why?

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Physics, Astronomy & Cosmology / how would you define ' Falsifiability ' in physics?

« on: 16/07/2018 11:21:33 »

To me it is a term that contradict itself,

A falsifiable TOE is one where you by simple logic prove it to be wrong if I get the idea correctly. If it in any sense can be proven to be wrong, how can a TOE ever exist?

And if one demand of any physical theory is that it must be proven to be falsifiable to be true, then?

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Physics, Astronomy & Cosmology / Does the universe lose energy as it expands?

« on: 07/04/2017 08:49:01 »

Geometrically I mean :)

Per inch, cm, whatever you prefer.

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Just Chat! / Some things I wonder about

« on: 17/02/2017 17:53:15 »

Make it a statement if you too wonder.

1. why don't we use the Internet to vote, and make our votes at a regular time, meaning at what you're interested in. We could create a system without 'politicians', but we don't?

2. Why do people think that making it unbearable for those needing a car, for work, or just to make the day, will stop the pollution we have?

2.a As a suggestion to the last, make public services 'smart' at any time of the day, and cheap instead.

(and I think we all know the real answer, it's a cheap way to increase incomes without increasing taxes Also 'stating' that you 'do something'.)



I do have some more, but I hope you too have thoughts on what makes you wonder.

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Physics, Astronomy & Cosmology / If an elephant jumps while aboard an aeroplane, does the plane get lighter?

« on: 11/02/2017 16:55:27 »

We have a aircraft,  in it a elephant jumps, as it do so does it count to the aircraft's mass?
Just argue, don't need to be perfect :)

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Just Chat! / What is life?

« on: 02/02/2017 14:39:39 »

Ok, I'm 'coming of age' as Tolkien would have had it.
And I'm at that point where I start to look back.

So?

What is it all about?

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Just Chat! / What irritates me with our new website

« on: 02/02/2017 05:40:29 »

1. Getting flooded in my mail by 'subscriptions' to threads I once wrote in, finding no way to turn it of in here?
It should be my choice if I want to 'subscribe'.

2. Finding no 'global' way of turning of those yellow fat moons (smileys) I just don't like them. I'm not into Facebook, twitter, etc and I don't think that everything I write need to be commented upon there, and the same goes for what you write :) btw.

In conclusion, the look of our new web site is nice and clean, but I'm missing global settings that we should be able to set, as well as I don't see what Facebook etc has to do with TNS?
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3. Okay, a third one. I used to be able to set a time for staying logged in. That seems gone now, and suddenly I find myself logged out without knowing. It may have to do with my choice of browser (Firefox), but in the first instances of this new version I still could set a time as I remember.

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Just Chat! / Kissing butt?

« on: 25/04/2015 16:27:46 »

Since Mathew and JP disappeared from this site it seems it's going downward. Don't know why? You're introducing bullying and gang behavior, which I, as I said before, find distasteful? Furthermore you don't seem to know the physics I present No big deal for me, but the former is. ah well, have fun following the decline.

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Physics, Astronomy & Cosmology / Anyone want to make a new theorem?

« on: 16/04/2015 17:36:02 »

Thinking of the brains structure, and the lungs

So?

Think of a towel, as the hitchhikers. How can you 'shrink' it topologically?
How close can it be?

Planck scale?

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Just Chat! / Why 0h why?

« on: 19/02/2015 21:32:18 »

keep getting

"The following error or errors occurred while posting this message:
Your session timed out while posting. Please try to re-submit your message."

Doesn't help if I allow all of the new scripts IP number and all, using FF clone and 'no script'. Restarting (Pale moon Version: 12.2.1) doesn't help

either. Seems that with each new 'upgrade' this site loses some functionality.

Let's see if I'm 'allowed' to post this then?
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Nope, restarted the dam* machine now and have allowed everything, including google analytics & apis, just to be sure. Also I'm wondering about this 'new'

IP number (81.201.132.39) that has shown up after the server change, disregarding that I already allowed TNS itself?
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I don't believe it.

Can't even log out it seems?

"An Error Has Occurred!
Session verification failed. Please try logging out and back in again, and then try again."

Ahh, and that came as I was trying to log out?

Ah well
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Last try, succeeded in logging out and then in again..
Fingers crossed.