beecee

Einstein gets it right again—weak and strong gravity objects fall the same way

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https://phys.org/news/2018-07-einstein-againweak-strong-gravity-fall.html

Einstein's understanding of gravity, as outlined in his general theory of relativity, predicts that all objects fall at the same rate, regardless of their mass or composition. This theory has passed test after test here on Earth, but does it still hold true for some of the most massive and dense objects in the known universe, an aspect of nature known as the Strong Equivalence Principle? An international team of astronomers has given this lingering question its most stringent test ever. Their findings, published in the journal Nature, show that Einstein's insights into gravity still hold sway, even in one of the most extreme scenarios the Universe can offer.

extract:

In 2011, the National Science Foundation's (NSF) Green Bank Telescope (GBT) discovered a natural laboratory to test this theory in extreme conditions: a triple star system called PSR J0337+1715, located about 4,200 light-years from Earth. This system contains a neutron star in a 1.6-day orbit with a white dwarf star, and the pair in a 327-day orbit with another white dwarf further away.

Through meticulous observations and careful calculations, the team was able to test the system's gravity using the pulses of the neutron star alone. They found that any acceleration difference between the neutron star and inner white dwarf is too small to detect.


Read more at: https://phys.org/news/2018-07-einstein-againweak-strong-gravity-fall.html#jCp
 

the paper: 

https://www.nature.com/articles/s41586-018-0265-1

Universality of free fall from the orbital motion of a pulsar in a stellar triple system:

 

Abstract:

Einstein’s theory of gravity—the general theory of relativity1—is based on the universality of free fall, which specifies that all objects accelerate identically in an external gravitational field. In contrast to almost all alternative theories of gravity2, the strong equivalence principle of general relativity requires universality of free fall to apply even to bodies with strong self-gravity. Direct tests of this principle using Solar System bodies3,4 are limited by the weak self-gravity of the bodies, and tests using pulsar–white-dwarf binaries5,6 have been limited by the weak gravitational pull of the Milky Way. PSR J0337+1715 is a hierarchical system of three stars (a stellar triple system) in which a binary consisting of a millisecond radio pulsar and a white dwarf in a 1.6-day orbit is itself in a 327-day orbit with another white dwarf. This system permits a test that compares how the gravitational pull of the outer white dwarf affects the pulsar, which has strong self-gravity, and the inner white dwarf. Here we report that the accelerations of the pulsar and its nearby white-dwarf companion differ fractionally by no more than 2.6 × 10−6. For a rough comparison, our limit on the strong-field Nordtvedt parameter, which measures violation of the universality of free fall, is a factor of ten smaller than that obtained from (weak-field) Solar System tests3,4 and a factor of almost a thousand smaller than that obtained from other strong-field tests5,6.

 

 

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Posted (edited)

Tom your disbelief in relativity has nothing to compare to the experimental evidence of its accuracy. It is one of the most strongly tested theories out there despite your lack of evidence to the contrary.

Quite frankly if you ever bothered to think about it under Newtonian physics a freely falling object the mass term of the falling body cancels out and does not depend on its mass or composition. Basic Newtonian physics describes the same thing for a falling body...

Edited by Mordred

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3 hours ago, Tom O'Neil said:

Utter nonsense if you really understand the universe you would ascribe to and all encompassing electric one based on fields.  The pseudoscience pervades physics to the core!

https://www.thunderbolts.info/wp/daily-tpod/ 

!

Moderator Note

This is not the place to register your dissatisfaction with or ignorance of physics

 

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see mod-note above. However I definitely support mainstream physics as well described by both Newtonian and GR. For very good reason.

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Posted (edited)
13 hours ago, beecee said:

https://phys.org/news/2018-07-einstein-againweak-strong-gravity-fall.html

Einstein's understanding of gravity, as outlined in his general theory of relativity, predicts that all objects fall at the same rate, regardless of their mass or composition. This theory has passed test after test here on Earth, but does it still hold true for some of the most massive and dense objects in the known universe, an aspect of nature known as the Strong Equivalence Principle? An international team of astronomers has given this lingering question its most stringent test ever. Their findings, published in the journal Nature, show that Einstein's insights into gravity still hold sway, even in one of the most extreme scenarios the Universe can offer.

extract:

In 2011, the National Science Foundation's (NSF) Green Bank Telescope (GBT) discovered a natural laboratory to test this theory in extreme conditions: a triple star system called PSR J0337+1715, located about 4,200 light-years from Earth. This system contains a neutron star in a 1.6-day orbit with a white dwarf star, and the pair in a 327-day orbit with another white dwarf further away.

Through meticulous observations and careful calculations, the team was able to test the system's gravity using the pulses of the neutron star alone. They found that any acceleration difference between the neutron star and inner white dwarf is too small to detect.


Read more at: https://phys.org/news/2018-07-einstein-againweak-strong-gravity-fall.html#jCp
 

the paper: 

https://www.nature.com/articles/s41586-018-0265-1

Universality of free fall from the orbital motion of a pulsar in a stellar triple system:

 

Abstract:

Einstein’s theory of gravity—the general theory of relativity1—is based on the universality of free fall, which specifies that all objects accelerate identically in an external gravitational field. In contrast to almost all alternative theories of gravity2, the strong equivalence principle of general relativity requires universality of free fall to apply even to bodies with strong self-gravity. Direct tests of this principle using Solar System bodies3,4 are limited by the weak self-gravity of the bodies, and tests using pulsar–white-dwarf binaries5,6 have been limited by the weak gravitational pull of the Milky Way. PSR J0337+1715 is a hierarchical system of three stars (a stellar triple system) in which a binary consisting of a millisecond radio pulsar and a white dwarf in a 1.6-day orbit is itself in a 327-day orbit with another white dwarf. This system permits a test that compares how the gravitational pull of the outer white dwarf affects the pulsar, which has strong self-gravity, and the inner white dwarf. Here we report that the accelerations of the pulsar and its nearby white-dwarf companion differ fractionally by no more than 2.6 × 10−6. For a rough comparison, our limit on the strong-field Nordtvedt parameter, which measures violation of the universality of free fall, is a factor of ten smaller than that obtained from (weak-field) Solar System tests3,4 and a factor of almost a thousand smaller than that obtained from other strong-field tests5,6.

 

 

I can’t stop to wonder how people were thinking when Newton expressed the laws of motion and did they feel the same sense of elegance coming from his formulations that we sense now from GR. I think they did, as Newton’s genius is definitely as profound as Einsteins. GR is too beautiful of a theory to be wrecked by some binary dwarf system out there yet its obviously missing something and that something has to be profound considering the circumstances of GR being experimentally untouchable for over a century now. I only hope that I will live to see more light being shed on this, what has been done in the last few years (Higgs Bozon) and what is happening now with plausible Sterile Neutrino is adding if not shaking the Standard Model of particles so the prospects are there. I just wish people like Gates, Buffett, Musk, Bezos would fund private physics research.

Edited by koti

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Posted (edited)
28 minutes ago, koti said:

I just wish people like Gates, Buffett, Musk, Bezos would fund private physics research.

Complete agreement. They should build their own CERN-clone.. Musk already has equipment for boring tunnels, which is required to build such research center..

 

Edited by Sensei

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Posted (edited)
On 7/5/2018 at 9:08 PM, koti said:

I can’t stop to wonder how people were thinking when Newton expressed the laws of motion and did they feel the same sense of elegance coming from his formulations that we sense now from GR.

Didn't Newton openly express, that despite the observational success of his laws of motion and gravity, that indeed he could give no reason why this attraction between masses exists? Einstein of course did explain this "attraction"  as due to the curvature of spacetime. Don't get me wrong, I'm in no way detracting from Newton's works.

Quote

I think they did, as Newton’s genius is definitely as profound as Einsteins.

No way would I argue or debate that point, other then to say that Einstein simply saw further because he had more shoulders of giants to stand on.

Quote

 

  I just wish people like Gates, Buffett, Musk, Bezos would fund private physics research. 

 

Perhaps if scientists/physicists such as Sean Carroll, and others were able to get into their ear about the importance of such research.

Edited by beecee

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Posted (edited)
39 minutes ago, beecee said:

Perhaps if scientists/physicists such as Sean Carroll, and others were able to get into their ear about the importance of such research.

You can give a man a book but you can't make him think. Besides those guys are about doing stuff, not thinking stuff. If they were interested, they'd be in it without being asked. Gates has his missions anyway.

Edited by StringJunky

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2 hours ago, StringJunky said:

You can give a man a book but you can't make him think. Besides those guys are about doing stuff, not thinking stuff. If they were interested, they'd be in it without being asked. Gates has his missions anyway.

True probably, but if one was to jog their collective memories, and get them to realise that most of what they do, is a result of theoretical research. Even if it stirs just one.....

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29 minutes ago, beecee said:

True probably, but if one was to jog their collective memories, and get them to realise that most of what they do, is a result of theoretical research. Even if it stirs just one.....

I don't have insight into any of their minds, or their recent transactions, but I find it hard to believe that either of those isn't funding fundamental physics research. Even if it's just a few million here or there

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7 hours ago, beecee said:

True probably, but if one was to jog their collective memories, and get them to realise that most of what they do, is a result of theoretical research. Even if it stirs just one.....

As Stringy said, Gates has his well placed agendas and is spending billions of Buffets and his own money on vaccine promotion and other medical issues...even if you aranged a meeting and gave me Janus for support I doubt he’d budge, its just not his thing. Buffet on the other hand never gets into endevours he doesn’t fully understand so that a no no too. Musk is obsessed with good PR which funding physics project would not give him and Bezos got his own expensive space project to worry about. Besides, CERN is such a big project that no single person or even a few billionairs could fund alone, it needs to be a collaborative effort to make it happen and theres no quick money to be made. 

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10 hours ago, koti said:

 Besides, CERN is such a big project that no single person or even a few billionairs could fund alone, it needs to be a collaborative effort to make it happen and theres no quick money to be made. 

I couldn't agree more. A shame more International efforts are not forthcoming to further bigger, better and more potentially knowledge revealing scientific experiments. When the SKA is properly up and running, we maybe in line for more exiting revelations. https://www.skatelescope.org/australia/

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