interested

[brodykade]

do galaxies rotate?

 

[lunatio_gordin]

Well, the stars in the galaxies do orbit the central black hole, so i suppose they do rotate. But it would occur over millions of years. Anyone know exactly how long the Sun's orbit is?

 

[vogon13]

IIRC, we go around the galaxy ~4 times every billion years. <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[ehs40]

so thats about 1 time about every 250 million years?

 

[vogon13]

Um, yeah. That's what my calculator says.<br /><br /><br />I have no idea how precisely this figure is known. I also don't know if the value of the eccentricity of the sun's orbit around the galaxy is known.<br /><br />Weird thinking solar system may have only been around the galaxy <20 times.<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[majornature]

Yes, galaxies do rotate because there is black hole in the center. For example, picture our sun as a black hole and our planets are galaxies that rotate around it. Our sun is the center point the controls the planetary rotational orbits in our solar system just like black hole in this case is the center point and it is controling the rotation of the cluster of stars around it.<br /><br /><b><font color="black">True Knowledge Exists in Knowing That You Know</font>/b><font color="white"><b> NOTHING!!!!!</b></font>/safety_wrapper></b> <div class="Discussion_UserSignature"> <font size="2" color="#14ea50"><strong><font size="1">We are born.  We live.  We experiment.  We rot.  We die.  and the whole process starts all over again!  Imagine That!</font><br /><br /><br /><img id="6e5c6b4c-0657-47dd-9476-1fbb47938264" style="width:176px;height:247px" src="http://sitelife.space.com/ver1.0/Content/images/store/14/4/6e5c6b4c-0657-47dd-9476-1fbb47938264.Large.jpg" alt="blog post photo" width="276" height="440" /><br /></strong></font> </div>

 

[spaceinator]

I wonder if whole galaxies orbit something too. or do they just move w/the supposed expansion of space...

 

[nacnud]

clusters of galaxies can orbit a common center of gravity

 

[john_316]

<br />How old are you brodykade?<br /><br />I ask this out of simple questioning compared to your other posts?<br />

 

[brodykade]

What are the gravitational effects of velocity in space?

 

[majornature]

It depends on two factors: reaching the practical gravitational boundary or transitioning into a free orbit.<br /><br /><b>GOD's greatest gift to the Universe is the Power of Learning and Discovering....</b><br /><br /> <div class="Discussion_UserSignature"> <font size="2" color="#14ea50"><strong><font size="1">We are born.  We live.  We experiment.  We rot.  We die.  and the whole process starts all over again!  Imagine That!</font><br /><br /><br /><img id="6e5c6b4c-0657-47dd-9476-1fbb47938264" style="width:176px;height:247px" src="http://sitelife.space.com/ver1.0/Content/images/store/14/4/6e5c6b4c-0657-47dd-9476-1fbb47938264.Large.jpg" alt="blog post photo" width="276" height="440" /><br /></strong></font> </div>

 

[nexium]

Velocity is relative, so all objects have many velocities depending on the reference. IMHO there are no gravitational effects due to velocity, except perhaps when a reference is selected with a speed difference of almost the speed of light. This would produce a large mass increase in the view of the fast observer. Neil

 

[brodykade]

So an object traveling at that velocity would have no gravitational effects on surrounding bodies?

 

[CalliArcale]

All matter has a gravitational affect on all other matter, regardless of speed. There are questions about whether this is transmitted instantaneously or not, however. That is to say, is there a speed of gravity? The question is debated, and I'm afraid it's also way over my head. <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[masta_shady]

Standard experimental techniques exist to determine the propagation speed of forces. When we apply these techniques to gravity, they all yield propagation speeds too great to measure, substantially faster than lightspeed. This is because gravity, in contrast to light, has no detectable aberration or propagation delay for its action, even for cases (such as binary pulsars) where sources of gravity accelerate significantly during the light time from source to target By contrast, the finite propagation speed of light causes radiation pressure forces to have a non-radial component causing orbits to decay (the "Poynting-Robertson effect"); but gravity has no counterpart force proportional to v/c to first order. General relativity (GR) explains these features by suggesting that gravitation (unlike electromagnetic forces) is a pure geometric effect of curved space-time, not a force of nature that propagates. Gravitational radiation, which surely does propagate at lightspeed but is a fifth order effect in v/c, is too small to play a role in explaining this difference in behavior between gravity and ordinary forces of nature. Problems with the causality principle also exist for GR in this connection, such as explaining how the external fields between binary black holes manage to continually update without benefit of communication with the masses hidden behind event horizons. These causality problems would be solved without any change to the mathematical formalism of GR, but only to its interpretation, if gravity is once again taken to be a propagating force of nature in flat spacetime with the propagation speed indicated by observational evidence and experiments: not less than 2 x 10^10 c. Such a change of perspective requires no change in the assumed character of gravitational radiation or its lightspeed propagation. Although faster-than-light force propagation speeds do violate Einstein special relativity (SR), they are in accord with Lorentzian relativity, which has never