# Einstein's Theory of General Relativity



## Drone (Feb 17, 2015)

Videos, links, anything.

http://www.space.com/17661-theory-general-relativity.html

http://science.nasa.gov/science-news/science-at-nasa/2011/04may_epic/


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## CAPSLOCKSTUCK (Feb 17, 2015)

Loved this bit from the 2nd link

_The four gyroscopes in GP-B are the most perfect spheres ever made by humans. These ping pong-sized balls of fused quartz and silicon are 1.5 inches across and never vary from a perfect sphere by more than 40 atomic layers. If the gyroscopes weren't so spherical, their spin axes would wobble even without the effects of relativity._







If we couldnt create perfect spheres we couldnt conduct experiments like those in GP-B.
Heres a quick vid on a very round thing, if you just want to know how, start at 08.00, its worth watching from the start though.












Gravity Visualized










@Frick 
EDIT  I saw a documentary on TV ages ago, unbelievably the most perfect spheres are created by one man, by touch, Incredible....i will find the vid and put it here if i can find it.


heres some New Scientist stuff
http://www.newscientist.com/article/dn14229-roundest-objects-in-the-world-created.html#.VONhrPmsWSo


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## Frick (Feb 17, 2015)

Were they made in space?


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## Drone (Feb 17, 2015)

Some video, an interesting link 










http://www.physicsoftheuniverse.com/topics_relativity_general.html

and famous consequence of Einstein's theory: Precession of the perihelion of Mercury

http://farside.ph.utexas.edu/teaching/336k/Newtonhtml/node116.html

In a nutshell:

Mercury moves around the Sun in ~ 116 days and its elliptical orbit itself also moves around the sun once every 3 million years. It's like those old yodawg jokes <so you can orbit while you orbit>


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## CAPSLOCKSTUCK (Feb 17, 2015)

I wonder if the Ancients had any idea of precession

http://en.wikipedia.org/wiki/Antikythera_mechanism

they had at least one example of an astrological computing device.


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## Drone (Feb 17, 2015)

They had no idea that space-time can be warped. Ideas of the _curvature_ of _spacetime_ stem from relativity theory.

And let's face it even now none of us can imagine curved space. We can imagine a curved line, a curved surface but not curved 3D space.

I can understand maths describing 4D or even higher dimensions and even _Riemannian geometry _but I'm unable to visualize it in my brain because our brains work like if our world was Euclidian but our world isn't Euclidian. It's curved and warped, it's _Riemannian. We always simplify everything and pretend that our world is simple _3D Euclidian space lol but it's not.


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## CAPSLOCKSTUCK (Feb 17, 2015)

Melon...........twisted.........again !








thanks a bunch @Drone


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## Drone (Nov 9, 2015)

Europe's 5th and 6th Galileo satellites - subject to complex salvage maneuvers following their launch last year into incorrect orbits - will help to perform an ambitious year-long test of Einstein's most famous theory.

The satellites' orbits remain elliptical, with each satellite climbing and falling some 8500 km twice per day. It is those regular shifts in height, and therefore gravity levels, that are valuable to researchers.

Albert Einstein predicted a century ago that time would pass more slowly close to a massive object. It has been verified experimentally, most significantly in 1976 when a hydrogen maser atomic clock on Gravity Probe A was launched 10 000 km into space, confirming the prediction to within 140 parts in a million.






This new effort takes advantage of the passive hydrogen maser atomic clock aboard each Galileo, the elongated orbits creating varying time dilation, and the continuous monitoring thanks to the global network of ground stations. The results are expected in about one year, projected to quadruple the accuracy on the Gravity Probe A results.


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## dorsetknob (Nov 9, 2015)

Good to see that they may get some useful unexpected science from those cocked up satellite orbital placements


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## Drone (Jan 30, 2016)

*Fundamental Ideas and Problems of the Theory of Relativity*

Lecture delivered to the Nordic Assembly of Naturalists at Gothenburg, July 11, 1923

Download pdf:

English
German




*Albert Einstein - Leiden Lecture, 1920
*
Read here


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## xfia (Jan 30, 2016)

this wouldnt be right without the opinion of one the worlds most brilliant physicists








joe and brian got me


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## 64K (Jan 30, 2016)

I picked up a book written by Einstein on Relativity that was intended to help people get a grasp of this subject that aren't physicists and I was lost pretty quickly. iirc this was the book


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## Drone (Jan 30, 2016)

64K said:


> I picked up a book written by Einstein on Relativity that was intended to help people get a grasp of this subject that aren't physicists and I was lost pretty quickly. iirc this was the book



Even physicists struggle with it. Einstein was way ahead of his time. Relativity is so revolutionary even 100 years later._ Btw that's a really good book_.

Understanding relativity without knowing physics/maths/geometry is simply impossible. All those asap pseudo-science videos won't really help.


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## xfia (Jan 30, 2016)

pseudo? einstein while a great thinker is not on the level of brian cox.. like seriously the crap you have said so far... ego.
there is a reason why he is the science face for pbs. tho you may not even know anything about pbs being a government institution for public education. He could take that einstein book cut out the nonsense and that would be the only way I would read it.
sorry you cant visualize anything but thats YOUR brain.. not humans.
you should be careful about slandering cern geniuses especially while your saying half your brain is broken and not presenting any actual point.. let alone expanding on it. 
your ego will now probably tell you that I am wrong and brian cox could never measure up to einstein but its wrong.. why? information!!  lets say you wanted to create your own race but you realize to do so you need a planet first and to tera form it.. well its going to take a life time to just figure out step one.


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## Drone (Jan 30, 2016)

xfia said:


> pseudo? einstein while a great thinker is not on the level of brian cox.. like seriously the crap you have said so far... ego.
> there is a reason why he is the science face for pbs. tho you may not even know anything about pbs being a government institution for public education. He could take that einstein book cut out the nonsense and that would be the only way I would read it.
> sorry you cant visualize anything but thats YOUR brain.. not humans.
> you should be careful about slandering cern geniuses especially while your saying half your brain is broken and not presenting any actual point.. let alone expanding on it.
> your ego will now probably tell you that I am wrong and brian cox could never measure up to einstein but its wrong.. why? information!!  lets say you wanted to create your own race but you realize to do so you need a planet first and to tera form it.. well its going to take a life time to just figure out step one.


First: I wasn't talking about Cox because I didn't even watch those videos, I was talking about bullshit youtube videos like general relativity in 30 seconds or something. Second, what's with those personal attacks? Who the hell are you to tell me what I know and what I don't. Telling that Einstein's book is full of nonsense already shows that you're the biggest retard ever.


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## xfia (Jan 30, 2016)

maybe you did and maybe you didnt but if you followed modern physics you would know some discussion from 1920 would mostly be useless..  explaining theory that has been disproven or trying to sell what is known as fact today.
i say half of it is nonsense but i am not as humble about it as todays physicists that would explain it like i did in my last sentence that you apparently ignored just like the visual representation of what you named the thread.


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## Drone (Jan 30, 2016)

xfia said:


> maybe you did and maybe you didnt but if you followed modern physics you would know some discussion from 1920 would mostly be useless..  explaining theory that has been disproven or trying to sell what is known as fact today.
> i say half of it is nonsense but i am not as humble about it as todays physicists that would explain it like i did in my last sentence that you apparently ignored just like the visual representation of what you named the thread.



Einstein's theory of relativity is old and incomplete because neither Einstein himself nor anyone else had power to complete it.

But seriously you say that it's disproven? What the hell. Everyday there's a new manifestation of Relativity that's being proved. Just because it started in early 20th century doesn't mean it's not working today. All maths are still valid today. Hence, it doesn't matter what relativity book people read these days. All "modern" scientists/writers write the same books on Relativity just with more "modern" language and jargon. Nothing in relativity was disproven or reinvented. And if you don't like my threads just don't post here.


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## xfia (Jan 31, 2016)

some of it is disproven just like some of it is a major thread of physics that holds it together.  
i would have to disagree that it does not matter what modern science book is read..  some scientists cant even agree on the speed of light but brian will tell you exactly what he thinks it is with his experience at the lhc.


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## silkstone (Jan 31, 2016)

@xfia The only things Einstein was actually wrong about was the cosmological constant. Which, in fact, he was actually right about at first before dismissing the idea as his "Biggest blunder".

Drone is right about humans not being able to "visualize" much of Einstein's work. I agree that we can make visualizations of it, but any visual representation is surely flawed. You draw me a picture, or make me a model of space and time bending and say that that is an accurate representation. you might draw a 2D plane and represent it being warped into the 3rd dimension, but this is not accurate.

Things like this can be conceptualized, i.e. we can understand what is happening. Any attempt to think about what it would actually 'look like' is the path to insanity, because it would look normal, we can not actually 'see' the bending of space-time.


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## Steevo (Jan 31, 2016)

Spacetime from our perspective looks like a blur of everything that happened frozen in the discrete samples we measure for a reference in the ever moving 4th time dimension, and everything is relative to the observer, so a spaceman that left earth would see it move faster as they went faster, and their reality or perspective would never match those of others.


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## xfia (Jan 31, 2016)

to say path to insanity would only make you seem to be a  christian radical but i can agree to disagree on visual representation


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## silkstone (Jan 31, 2016)

Steevo said:


> Spacetime from our perspective looks like a blur of everything that happened frozen in the discrete samples we measure for a reference in the ever moving 4th time dimension, and everything is relative to the observer, so a spaceman that left earth would see it move faster as they went faster, and their reality or perspective would never match those of others.



That is true, if you were able to actually 'see' what was happening. It's more the actual 'bending' of space time or what it would look like. As it is not really 'bending' or 'warping,' the best we can do is come up with analogies which only really model what is happening. The more you try to visualize these things, the more confusing it becomes. The majority of these concepts can only really be explained mathematically. It is not that some people are able to do it and others aren't, it is that we have visual concept of anything other than the 3-spacial dimensions and when trying to 'bend' those dimensions into a fourth spacial dimension, as human brains aren't able to perceive a 4th special dimension, it is impossible to visualize.

In a similar way, we can not visualize non-existence, i.e. what is beyond the 'edge' of the universe? The answer to this is not 'nothing' as nothingness is still existence. Go ahead, visualize non-existence. What do you see, describe it?

Edit - And I am a true believer in Pastafarianism. I can not believe that Zombie's are real.

Edit 2 - https://www.quora.com/Relativity-physics/If-matter-bends-spacetime-what-does-it-bend-in
There are some good descriptions about what is actually happening in this thread. They should allow you to 'conceptualize' it a little better.


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## xfia (Jan 31, 2016)

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

not sure if your joking but this^  
these peoples brains are truly broken wanting others to be broken with them and feed off the unconsciousness.


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## silkstone (Jan 31, 2016)

Read up on the history of the church (of the FSM) and it's purpose. It should become clear.


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## xfia (Jan 31, 2016)

I am the sentience that rises from what is eternal.. I am a wave and a particle.. I exist here and there while being bound to the physical... I observe and worlds change..


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## the54thvoid (Jan 31, 2016)

xfia said:


> I am the sentience that rises from what is eternal.. I am a wave and a particle.. I exist here and there while being bound to the physical... I observe and worlds change..



Take your pills and go to bed. Stop trolling with misguided musings.


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## xfia (Jan 31, 2016)

the54thvoid said:


> Take your pills and go to bed. Stop trolling with misguided musings.


there is nothing false about it.. i just made it my own. what do you believe in the noodle that controls the universe too?
like honestly.. you say that to me and have nothing to say about noodles.
seriously cant make any of this dumb ass shit up.
edit-this is how i feel when i enrage the noodle heads 








edit-had to find this one but it was work it.. 7min in you will learn that einstein was a lot like brian cox and explained often with visual representation.
they understand the mathematical constant that enables them to do so and thats all there is to it.


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## CAPSLOCKSTUCK (Feb 11, 2016)

LIGO confirms gravitational waves








https://www.ligo.caltech.edu/

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



and involvement from the UK

http://www.bbc.co.uk/news/uk-wales-35533167


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## Drone (Feb 11, 2016)

^ Unbelievable

http://www.nsf.gov/news/news_summ.jsp?cntn_id=137628


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## Sasqui (Feb 11, 2016)

I'm bummed... was hoping to learn that gravitational waves break the cosmic speed limit of "c", but apparently not:  http://www.universetoday.com/121284/how-fast-is-gravity/


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## Drone (Feb 11, 2016)

Three other nice videos by Caltech and MIT


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## dorsetknob (Feb 11, 2016)




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## Drone (Feb 13, 2016)

Two interesting interviews with Stephen Hawking and Neil deGrasse Tyson on gravitational waves and LIGO



















Neil deGrasse Tyson has a good explanation and Stephen Hawking provided really interesting facts about black holes. Media says that LIGO experiment confirmed Einstein's theory but it also confirmed Hawking's theory.


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## Drone (Feb 15, 2016)




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## Caring1 (Feb 15, 2016)

I've got a feeling they missed something when the two black holes merged, there should have been something more than just gravitational waves when two very powerful forces combine.


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## silkstone (Feb 15, 2016)

Caring1 said:


> I've got a feeling they missed something when the two black holes merged, there should have been something more than just gravitational waves when two very powerful forces combine.



It really depends on how far away it happened and if we have something looking at it when it happened. I believe the detector for gravitational waves gives little indication of direction. It is a relatively small event and a very large sky.

The inverse square law is a real bitch when dealing with distances on the scale of the universe.


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## Tatty_One (Feb 15, 2016)

I saw this on the news, quite a detailed and thought provoking piece, my first thoughts were, and forgive me, this is NOT intended as a Troll but who cares?  I do genuinely find it interesting but the Human race ploughs billions into research to trying to learn what goes on and is happening 6 million light years away whilst millions are dying in our own back yards either through hunger, disease or conflict, I appreciate that by a better understanding of the universe it may help sustain our planet and race for the future but surely if we don't get the "now" sorted then there is no future in any case?
Apologies #BackONtrackNow


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## Drone (Feb 15, 2016)

two videos from World Science Festival

What will we learn from the detection of gravitational waves? 










Brian Greene explains the discovery of gravitational waves










Lol almost everyone I know already explained that


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## FordGT90Concept (Feb 15, 2016)

Gravity waves are nice and all but that still doesn't explain the motion of galaxies.  The center of galaxies, whatever it is, causes not only a gravitational effect, but it causes the fabric of space-time to move as well.  In that ESA video, imagine him rotating that aparatus while the marble is moving around the weight--that's the effect the center of galaxies has on everything that surrounds it.  Whatever is capable of not only bending space-time, but also warping it (rotating, in the case of spiral galaxies), that's what piques my interest.


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## Drone (Feb 15, 2016)

Back in the day scientists theorized that entire Universe (like you said space-time) rotates. Recently that theory was proved wrong. It doesn't rotate, though our galaxy and others do.


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## FordGT90Concept (Feb 15, 2016)

The fabric of space-time on the universe-scale is stretching.  If you go from the beginning of time to today, it looks like a logorithm





The rotation of space-time is centered around galaxies, or rather, the core of each one.  In the context of the universe, it's localized.  That is to say: galaxies are moving farther apart from each other at a rate that is logorithmically increasing.  Each galaxy is rotating not only the fabric of space-time, but also due to gravity.  Each star is trapped in the gravity well of the galaxy, planets are trapped in the gravity well of the stars, and moons are trapped in the gravity well of planets.

The key to faster than light travel may be in the mechanics of how galaxies tear (for lack of a better word) at the fabric of space-time.


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## Drone (Feb 15, 2016)

Spinning Universe business is really fishy. Lots of speculations. Some say yes others say no.

http://news.discovery.com/space/do-we-live-in-a-spinning-universe-110708.htm
http://www.dailygalaxy.com/my_weblog/2011/07/-is-the-universe-spinning-new-research-says-yes.html
http://physicsworld.com/cws/article/news/2011/jul/25/was-the-universe-born-spinning
http://ns.umich.edu/new/releases/84...to-new-findings-on-the-symmetry-of-the-cosmos
http://www.earlyuniverse.org/is-the-universe-rotating/

Here's the snippet from an article from University of Illinois

Q. Does our Universe spin/rotate?

A. As far as we know the answer is no. Astronomers have looked at the spin and rotation directions of a large number of galaxies but the net angular momentum is zero, within statistical uncertainties.  You can always find a few local anomalies but, again, consistent with statistical fluctuations.


I have read somewhere that some experiment (WMAP or was it something else I don't remember so don't wanna lie) dismissed spinning universe idea.



The only thing is certain it's expanding due to Cosmological Constant; expansion is accelerating and that space-time is relatively flat and homogenous and isotropic with temperature 2.73 K.


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## 64K (Feb 15, 2016)

Drone said:


> The only thing is certain it's expanding due to Cosmological Constant; expansion is accelerating and that space-time is relatively flat and homogenous and isotropic with temperature 2.73 K.



That's the thing that I can't wrap my head around. The expansion is thought to be accelerating. I see The Big Bang as an explosion where all the mass and energy in space came from. I can picture that it is still expanding but I don't understand how the expansion could be accelerating. It would seem to me that gravity would slow the expansion eventually and reverse back to a central point in space and perhaps cause another Big Bang.

I'm wondering if some force from outside the known universe is pulling us or some force withing the known universe is pushing on us and we don't know what that is. I just can't connect what I think of as gravity pulling objects together and somehow we are accelerating faster apart.


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## Drone (Feb 15, 2016)

64K said:


> That's the thing that I can't wrap my head around. The expansion is thought to be accelerating. I see The Big Bang as an explosion where all the mass and energy in space came from. I can picture that it is still expanding but I don't understand how the expansion could be accelerating. It would seem to me that gravity would slow the expansion eventually and reverse back to a central point in space and perhaps cause another Big Bang.
> 
> I'm wondering if some force from outside the known universe is pulling us or some force withing the known universe is pushing on us and we don't know what that is. I just can't connect what I think of as gravity pulling objects together and somehow we are accelerating faster apart.



Big Bang wasn't an "actual explosion" (see this link). It was all because of inflation, btw some scientists even don't believe in inflation. What caused all that is a mystery even today. Some say it was neutrinos that messed up, others say like you said it was some other Universe pulling on ours, or maybe it was a big collapse of previous Universe (Big Crunch) which caused the creation of our Universe (cyclical cosmology and Big Bounce). Not all galaxies are running away from each other, it depends on a distance between them (Hubble's law). Lots of galaxies actually are colliding/merging, like Milky Way and Andromeda some billion years later.


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## FordGT90Concept (Feb 15, 2016)

Drone said:


> Spinning Universe business is really fishy. Lots of speculations. Some say yes others say no.


I'm not talking about the universe spinning.  I didn't even mean to suggest it.  I've been talking about galaxies.



Drone said:


> The only thing is certain it's expanding due to Cosmological Constant; expansion is accelerating and that space-time is relatively flat and homogenous and isotropic with temperature 2.73 K.


Yes, which is why I think logorithm is a really good explaination of this.  When the big bang occured, the acceleration of space-time was extremly rapid but it then tapered off.  It is still accelerating but the rate of acceleration is inccreasing ad infinitum.  Logorithm never reaches 100%...it's always accelerating a fraction of a percent (99.9, 99.99, 99.999, 99.9999, and so on).  The longer we go out, the flatter it gets, but the curve never goes completely flat.

Maybe I'm thinking expontential decay (where it never reaches 0) but the curve looks more like logorithm.


I don't think a "big crunch" will ever happen, especially if what I said above is true.  The universe may never stop expanding.  Even with the universe still expanding, gravity still is at play to bring galaxies together if their attractive force exceeds the rate the expanding universe is driving them apart.


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## Caring1 (Feb 15, 2016)

64K said:


> I'm wondering if some force from outside the known universe is pulling us or some force withing the known universe is pushing on us and we don't know what that is. I just can't connect what I think of as gravity pulling objects together and somehow we are accelerating faster apart.


http://csep10.phys.utk.edu/astr162/lect/gclusters/attractor.html
Perhaps this is a cause, for our section of the universe anyway.


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## FordGT90Concept (Feb 15, 2016)

If you imagine a body that houses billions of galaxies...what would it behave like? Would it describe the "Great Attractor?"

There's a well observed relationship between moons, planets, and stars pretty easily explained by gravity.
There's also a well observed relationship between galaxies that is not unlike that of moons, planets, and stars but at a much grander scale (clusters).
Does it not stand to reason that clusters of galaxies could not have a similar relationship on an even grander scale with other clusters of galaxies (super clusters)?
Does this relationship of grander and even more grander ever end?

The "Great Attractor" may be composed of the same stuff Sagittarius A* is.  Then again, it may not.


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## Drone (Feb 15, 2016)

FordGT90Concept said:


> I'm not talking about the universe spinning.  I didn't even mean to suggest it.  I've been talking about galaxies.


 The fact that galaxies are rotating is known since forever. Angular momentum and their shape show it perfectly.



> I don't think a "big crunch" will ever happen, especially if what I said above is true. The universe may never stop expanding.


It can easily stop expanding. Neil Turok has a theorem about that (False Vacuum decay) and metastable Higgs bosons can wreck a havoc or two and cause Big Crunch according to Stephen Hawking.


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## FordGT90Concept (Feb 15, 2016)

Drone said:


> The fact that galaxies are rotating is known since forever. Angular momentum and their shape show it perfectly.


Angular momentum can describe stellar movements, not galactic.  Here's an article:
http://www.scientificamerican.com/article/what-process-creates-and/


> "The basic physics of why galaxies have spirals is known, but the details remain controversial, sometimes intensely so. Spirals exist only among flattened or 'disk' galaxies. These galaxies are differentially rotating--that is, the time to complete a full rotation increases with distance from the center. Differential rotation causes any disturbance in the disk to wind up into a spiral form. *The trouble with this simple explanation is that the differential rotation would cause spiral features to wind up too quickly, so galaxies would not look like spirals for any appreciable length of time.*


My explaination: space-time is rotating too.  If you take into account angular-momentum and space-time rotation, you can consistently get the sprials that are observed.

Obviously there's a lot of theories out there that may explain it.  Just food for thought.


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## Drone (Feb 15, 2016)

Back to Albert.

Found interesting article:

Einstein Likely Never Said One of His Most Oft-Quoted Phrases
The great scientist certainly regretted introducing the "cosmological constant" into his equations, but calling it his "biggest blunder"? Not so much, it seems.

This meme comes to mind:


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## Drone (Mar 2, 2016)

two new videos


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## Drone (Mar 6, 2016)

I guess Kip should do part 2


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## Drone (Mar 22, 2016)

Public Lecture - Gravitational Waves

Victoria’s Professor Matt Visser, a world-leading expert in general relativity, and Associate Professor Melanie Johnston-Hollitt, an internationally prominent radio astronomer, share their insights on how it was discovered, what it means, and the future of astrophysics.


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## misternikitas (Mar 22, 2016)

God damn I was talking with a friend about it today. I don't think its just a coincidence.


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## Drone (May 12, 2016)

*An international team led by Japanese researchers has made a 3D map of 3000 galaxies 13 billion ly from Earth, and found that Einstein's general theory of relativity is still valid*.







Their results indicated that even far into the Universe, general relativity is valid, giving further support that the expansion of the Universe could be explained by a *cosmological constant*, as proposed by Einstein in his theory of general relativity.

No one has been able to analyze galaxies > 10 billion ly away, but the team managed to break this barrier thanks to the FMOS (Fiber Multi-Object Spectrograph) on the Subaru Telescope, which can analyze galaxies 12.4 - 14.7 billion ly away. The Prime Focus Spectrograph, currently under construction, is expected to be able to study galaxies even further away.


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