1

Physics, Astronomy & Cosmology / Re: what is the rate of time dilation in Einstiens 1g lift with no windows

« on: 23/09/2022 00:42:14 »

Hi all,
yes Halc, sorry I wasn't clear.

I am wondering if its possible to calculate the time dilation/rate of a light clock in Einstein's classic lift with no windows accelerating at 1g  vs one stationary/not accelerating far away from any gravitational effects.

Similar as to how you would calculate/compare the rate of a stationary clock at sea level on Earth vs one stationary/not accelerating far away from any gravitational effects, as per the standard gravitational time dilation equations.

I read somewhere the centripetal/centrifugal acceleration of a mass correlated to time dilation equivalent to the linear velocity of the body in question, but I am not sure how accurate this information is, or if its possible to mathematically relate it to the question I am posing.
 

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Physics, Astronomy & Cosmology / Re: what is the rate of time dilation in Einstiens 1g lift with no windows

« on: 12/09/2022 00:44:04 »

Hi all,

Halc isnt escape velocity  the speed at which the sum of an object's kinetic energy and its gravitational potential energy is equal to zero 

3

Physics, Astronomy & Cosmology / what is the rate of time dilation in Einstiens 1g lift with no windows

« on: 12/09/2022 00:04:25 »

Hi all,

previously it has been discussed that time dilation is linked to energy potential, therefore different planets can have the same surface value of g but different escape velocity's.
Therefore how would it be possible to calculate the time dilation for a box with no windows accelerating at a rate of one g  ?  (in empty space)
 

4

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

« on: 16/07/2022 09:45:43 »

Hi all
yes Halc I thought you were using more than one theory, as they disagree/conflict on some of the points you raise.

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.

This

Water waves, sound waves, and electromagnetic waves are able to carry energy, momentum, and angular momentum and by doing so they carry those away from the source

From
https://en.wikipedia.org/wiki/Gravitational_wave#Energy,_momentum,_and_angular_momentum

yes I would agree its obviously not a closed system. and its not just gravity waves that can carry away angular momentum. 

5

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

« on: 13/07/2022 15:49:07 »

HI all
sorry Evan I've not visited recently
But think the context I used was fine.

.http://hyperphysics.phy-astr.gsu.edu/hbase/tide.html#:~:text=Go%20Back-,Sun's%20Tidal%20Effect,gravity%20field%20across%20the%20Earth.

Also Halc

It isn't an energy thing. The vast majority (over 99%, about 97% for lunar tides) of the energy dissipates as heat. Its the angular momentum that counts since that cannot just be radiated into space,

Also

It's about conservation of angular momentum.
Both sun and Earth-system have spin, and in the same general direction. This momentum must be conserved. The energy is not conserved

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.
 

https://en.wikipedia.org/wiki/Gravitational_wave#Energy,_momentum,_and_angular_momentum

6

Physics, Astronomy & Cosmology / Re: Is mass a number?

« on: 02/05/2022 18:59:59 »

Hi all,

OK varsigma,
If I understand your request correctly regarding is mass a number rather than a physical thing.
Its based on empirically proven physical constants, to allow precise replication. 

So the unit of mass is the Kg Kilogram in the system of international units, which was originally simply the mass of a litre of water, which is actually accurate to 30 parts per million.

However in 1799, it was replaced by an all-platinum kilogram prototype that was fabricated with the objective that it would equal, as close as was scientifically feasible for the day, the mass of one cubic decimetre of water at 4 °C. It was called the Kilogramme des Archives as it was stored in the Archives Nationales in Paris.

This remained the SI standard till 2019.
https://en.wikipedia.org/wiki/International_System_of_Units

The kilogram was the last of the SI units to be defined by a physical artifact, although precision kilogram masses remain in use as secondary standards for ordinary purposes.

https://en.wikipedia.org/wiki/Kilogram#Redefinition_based_on_fundamental_constants

The requirement to produce replicas caused  the mass of these to vary by amounts approximately 50 micro grams.

Therefore,

The International Committee for Weights and Measures (CIPM) approved a redefinition of the SI base units in November 2018 that defines the kilogram by defining the Planck constant to be exactly 6.62607015×10−34 kg⋅m2⋅s−1, effectively defining the kilogram in terms of the SI base units  "second" and the "metre".

Therefore, dimensions of energy times time, (mass × length^2 / time) together with other physical constants
This was done so that the standard can be independently reproduced in different laboratories by following a written specification, from empirically proven physical constants.
And the units were coherent to mass length and time.

https://en.wikipedia.org/wiki/Kilogram#Acceptance_of_the_Giorgi_system,_leading_to_the_MKSA_system_and_the_SI

To summarize, the ultimate reason that the kilogram was chosen over the gram as the base unit of mass was, in one word, the volt-ampere. Namely, the combination of the meter and the kilogram was the only choice of base units of length and mass such that 1. the volt-ampere—which is also called the watt and which is the unit of power in the practical system of electrical units—is coherent, 2. the base units of length and mass are decimal multiples or submultiples of the meter and the gram, and 3. the base units of length and mass have convenient sizes.

It would appear the Kibble balance is the dominate apparatus in this regard.

 https://en.wikipedia.org/wiki/Kibble_balance


which hopefully the design/engineering  explains  to you how mass is not just a number but a based on combination of physical constants allows a very accurate replication of fixed amount of Mass.

A conducting wire of length L that carries an electric current I perpendicular to a magnetic field of strength B experiences a Lorentz force equal to the product of these variables. In the Kibble balance, the current is varied so that this force counteracts the weight w of a mass m to be measured. This principle is derived from the ampere balance. w is given by the mass m multiplied by the local gravitational acceleration g

weight = mg = BLI

https://en.wikipedia.org/wiki/Lorentz_force

7

Question of the Week / Re: Can the Earth be used as a dynamo?

« on: 02/05/2022 12:17:29 »

Hi all

Thanks for that Evan, my bold

- Some have even recently speculated (based on seismology) that the remnants of Theia's core are still sinking to coalesce with the Earth's core
- This causes convection currents in the outer core
- This interacts with the rotation of the Earth to generate electric currents in the outer core, which generates the Earth's magnetic field

As you state there is still a lot of speculation in this regard, and some of the modeling being done is even testing the capacity of super computers.
But there are some fundamentals required in these models

eg,   conversion of kinetic energy to magnetic energy, and a requisite is part of the Kinetic energy is provided by planetary rotation.

So the point raised by wolfekeeper remains.

Along with the similarity to the work heat equivalence experiments of Joule, we can observe as the friction with local geography of the solid earth passes/interacts with these tidal bulges, due to its rotation.

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Question of the Week / Re: Can the Earth be used as a dynamo?

« on: 01/05/2022 17:53:17 »

Hi all

Trying to develop energy from the mechanical rotation of the earth would involve insurmountable difficulties despite being theoretically possible.An isolated structure that is static with reference to the rotating earth or rotating with a shorter or longer period than the earth would be required first. then this structure would be required to follow the track of the earth around the sun.Not at all practical and i'm sure there could be other difficulties involved.

Does the tidal bulge not satisfy those requirements ?

If so its pretty straight forward and is already being done.

https://en.wikipedia.org/wiki/Tidal_power


Also the tidal effects due to the Moon are greater than due to the Sun

http://hyperphysics.phy-astr.gsu.edu/hbase/tide.html#:~:text=Go%20Back-,Sun's%20Tidal%20Effect,gravity%20field%20across%20the%20Earth.

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Question of the Week / Re: Can the Earth be used as a dynamo?

« on: 30/04/2022 09:57:18 »

Hi all,

So wolfekeeper you raise an important contradiction to evan_au posts.

Less directly, the spinning of the Earth interacts with the gravitational pull of the Sun and Moon to generate ocean tides, and the tidal currents can be used to generate electricity.

No water is pumped up in the suns and moons gravitational field and no friction occurs as the solid Earth rotates passed these bulges ?

The Earth spinning does set up electric currents in liquid iron in the outer core of the Earth. This generates the Earth's magnetic field, which shields our atmosphere from the solar wind.

what powers this generation of electro magnetic currents ? and how is it isolated from placing a load on the rotation of Earth ?
 

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That CAN'T be true! / Re: where does Colin's sailing boat, energy and momentum come from ?

« on: 13/04/2022 10:55:57 »

Hi all,

BC

You also seem not to recognise that, on any given day, the angular momentum of the atmosphere may be a bit higher or lower than the average

So to be clear, I believe it is possible the average angular momentum total fluctuates, for the reasons given previously,
the sharing of angular momentum between the atmosphere and the solid earth became the go to explanation of the underlying annual fluctuation.

I believe it can be explained as terminal velocity.

   
BC

It is conserved because there is no torque acting on the system (apart from a few thing we have discussed, such as the tides).

That indeed is the current thinking, which I believe falls short of the physical reality, I think there is potential alternative explanations as to the fluctuations of LOD that indeed require forces not yet identified.

To explain these forces although a simple mechanism, I will have to go across a broad range of examples and correlations of physical events.

For example a potential link to galaxy rotation curves and G 

 

11

Chemistry / Re: What happens when you melt gold into glass?

« on: 10/04/2022 13:06:08 »

Hi Marcos,

Quite a while ago I bought a piece of art from these people local to me, which I believe utilizes some of the specialist techniques/knowledge you are requesting.
 
https://www.greenhalghglass.co.uk/gallery.html

12

General Science / Re: Antarctic science greenhouse emissions

« on: 10/04/2022 12:53:18 »

HI all,

So BC,

Or they hit the top of a mountain

I'm not sure what your point is there given Alan's post.

I believe he was making the point of  coral conditions, are you referring to seamounts ?
 

13

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

« on: 04/04/2022 23:45:21 »

Hi all,

Halc, yes I take your point regarding gear equivalence for skating technique, its not my strong suit, think Bambi on ice and you have a pretty good visualization.

Take a look at the link below it covers some of the points as to the physics.

It does state, the mechanical advantage of the  pedal system of gears does allow a much greater Tyre speed vs leg speed.
 
https://physics.stackexchange.com/questions/505636/what-determines-the-top-speed-in-ice-skating

I believe someone raised the point of the similarity with sailing dynamics as to forward motion gained from a side on wind.
 

14

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

« on: 01/04/2022 15:04:27 »

HI all

Halc

I did think about why bikes are faster than skating. Biking seems almost 100% efficient, almost all the mechanical energy going into forward thrust, whereas the skater is thrusting against his own inertia, sending his center of gravity from side to side. That's a lot of work, even though half of it is negative work being done. The human body doesn't capture negative work very well. Again, a kangaroo does. They're designed to absorb the energy of coming down and bounce back up again, using energy only to add to it a bit. Hence the skater wasting a lot of energy that the cyclist doesn't

Bikes have gears which would account for the faster speed 

rather than straight comparison of energy efficiency

https://www.popularmechanics.com/adventure/outdoor-gear/a22061530/how-bike-gears-work/

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Question of the Week / Re: QotW - 22.03.21 - Does relativity make rocks on the moon older than Earth rocks?

« on: 27/03/2022 10:09:51 »

Hi all,

I think we maybe wondering a little from the original question, however given eternal student's last comment, it maybe relevant to flag up you have to be careful with your comparisons/analogy's


ES

A planet is a mole-hill in the area, everything is really on the slopes of Mount Everest anyway.

     

I believe using the word slope in this context is misleading and will bring you back to the same issue Janus raised regarding gravitational time dilation error in the wording of the original question.

Given the slope of the well tells you how hard the pull of gravity is at that point.

The depth of the well tells you how much energy it takes to escape.

https://en.wikipedia.org/wiki/Gravitational_potential#/media/File:GravityPotential.jpg

 

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Question of the Week / Re: QotW - 22.03.21 - Does relativity make rocks on the moon older than Earth rocks?

« on: 25/03/2022 00:49:51 »

HI all,

Ok to have a stab at putting an approx value to the original question for gravitational time dilation due only to their gravity well.

using the analogy of a rock split in half from the surface of the earth and each half remained on the surface of their respective bodies, from an impact event occurring 4.51 billion years ago

Earth time dilation = 6.965 x 10^-10 sec/sec

Moon time dilation = 3.15 x 10^-11 sec/sec

I get the Earth to be 1095 days younger than the moon which may seem like a lot but is only

                                            66.51 x 10^-9 % different

I am happy to be corrected if anyone else wants to chip in.
 

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Question of the Week / Re: QotW - 22.03.21 - Does relativity make rocks on the moon older than Earth rocks?

« on: 24/03/2022 14:12:32 »

Hi all,

Thank you Janus for that response, it sits better with me than the previous analogy of a gravity field not following the inverse square law.

If I may borrow part of your explanation to respond, and explain why/how I understand your statement is correct :

Janus
 

First off, the time dilation is not due to a difference in the strength of gravity, but to a difference in gravitational potential.

So firstly if you calculate the strength of g and escape velocity and time dilation at the Earths surface gives

                                    g  = 9.82 m/s^2
             escape velocity  =  11.19 x10^3 m/s
                  time dilation  =  + 6.97 x10^-10 sec/sec

Then to borrow your example:
 "Now double the Earth's radius and quadruple its mass"

Lets call this plant B gives the following equivalent values.

                                g  = 9.82 m/s^2
             escape velocity  =  15.82 x10^3 m/s
                  time dilation  =  + 1.39 x10^-9 sec/sec

As can be seen the identical value of g for Earth and planet B at their surface, but a different value for escape velocity and therefore gravitational time dilation.

 

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Question of the Week / Re: QotW - 22.03.21 - Does relativity make rocks on the moon older than Earth rocks?

« on: 23/03/2022 00:00:38 »

HI all
Janus

First off, the time dilation is not due to a difference in the strength of gravity, but to a difference in gravitational potential.
To illustrate the difference, imagine you had a uniform gravity field (one that did not change in strength with altitude). If you place two clock at different heights in this field, the higher clock runs faster even though it feels exactly the same gravitational force as the lower clock.

Has this been shown experimentally, if so could you provide information please.

19

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

« on: 20/03/2022 01:21:44 »

Hi all,
 Hamdani you raise a interesting scenario,

BC

Energy will flow until equilibrium is achieved.

It was already at equilibrium.

I am not sure that statement is totally correct, if you consider the energy imbalance between the two sides as described,
for example the latent heat/energy is unbalanced as is the kinetic energy of the molecules, also the density's.   

20

That CAN'T be true! / Re: Are Flat Earthers really for real?

« on: 02/03/2022 01:09:43 »

Hi all

Yes I believe some of them are for real, even one of the pioneers of the flat earth society,
https://en.wikipedia.org/wiki/Lady_Elizabeth_Blount
was from/one of the;
 https://en.wikipedia.org/wiki/Intelligentsia

There was some interesting characters and happenings around the;
https://en.wikipedia.org/wiki/Bedford_Level_experiment

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