Expanding Universe

[dragon04]

<font color="yellow">If we observe an object 14 billion lyrs away it seems to be going away faster than an object 7 billion lyrs away.<br /><br />Why do scientists believe this is evidence that the universe's expansion is accelerating?</font><br /><br />That in and of itself is the proof. If you think about the volume of a sphere, the "outside" has more mass than its interior.<br /><br />IOW, there is much more mass 10 billion LY away than there is 2 billion LY away.<br /><br /><font color="yellow">What is to say that the distant object is going the same speed as the closer object in real time and the only reason it appears to be going faster is because of the time lag? Maybe our view of it appears faster 'cause it is coming from an older, more rapidly expanding universe.</font><br /><br />Think about it this way.... An explosion releases an initial force that decreases as the explosion heads towards its conclusion.<br /><br />The first bits of mass ejected will be ejected at a higher velocity than the last bits. As the explosion loses its energy, and remaining matter closer in will be pushed out at a slower rate until the explosion expends all its energy. <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[primordial]

Mr. Johnr1! Yes, the less gravity, the faster the clock runs, agreed, so if your in the present, and gravity is becoming less, and observing a clock in the past you would see the clock run slower, so an event that an observer would see in the future would to him be slower or red shifted, right?<br />

 

[dragon04]

That's why the observed accelerating expansion of the Universe is so enigmatic.<br /><br />Based on what we know, it shouldn't be happening. <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[primordial]

Mr. Dragon04! Could the rapid expansion be due to the transitions made through the horizons generated by the local density. If the local density of a cluster "approches" a Schwarzschild Radius of what Stephen Hawking calls a black hole, Then an observer in such a dense cluster would see the rest of the universe transverse through time in a much faster rate. All these effects could possibly happen in a quasi Steady State universe, Or Quasi expanding universe.

 

[primordial]

Mr. ranur! Thanks for the info. I'll keep my eyes open for it , It sounds interesting.

 

[R1]

primordial I haven't thought about this factor but yes I do believe the event would be red shifted<br /><br />this thread is full of interesting things. I hope to see more input on this time aspect.<br />The Cesium clocking atoms from the past would in my opinion then be red shifted and slower<br />from the gravity in the early universe when density (gravity in particular) was cosmically high <br /><br />(the Cesium I just added as an illustrative thought, what I mean is actually the speed of time passage) <div class="Discussion_UserSignature"> </div>

 

[alokmohan]

Is it happening?

 

[siarad]

<blockquote><font class="small">In reply to:</font><hr /><p>I understand what you are saying it's almost like the density of the universe is becoming less with time passing<p><hr /></p></p></blockquote><br />It seems to me weird that the magnetic & electric co-efficients of space are not being diluted by space expansion since the speed of light is un-changing, permittivityxpermeability = 1/c^2 (u.e = 1/c^2). Is space being manufacturd rather than stretching.<br />

 

[R1]

interesting, but does this hold true whether you wish to observe a wave as oposed to particle?<br /><br />so even if 2 observers were 12 billion lightyrs. apart the photon sensed by observer #1 would actually<br />vanish out of observer # 2's reality 'instantaneously' throgh 12 billion years of separation?<br /><br /><br /><br /><br /> <div class="Discussion_UserSignature"> </div>

 

[mytheory]

I like your view on this matter, I'm glad you mentioned this. I believe that telescopic development by humans has advanced to quickly for us to understand what we are seeing. We may think we now what we are seeing when we look into a telescope and look back into space and time, but I'm not so convinced! Humans have no idea how the universe even began, we have theories but no signifigant eveidence on this matter. When we look back in to space and time through a telescope how do we know if we are looking away from or toward the point of the great explosion or (Big Bang) and how the expansion of these two directions compare... this topic boggels my mind, and gives me a headache haa <div class="Discussion_UserSignature"> <span style="font-weight:bold" class="Apple-style-span">@LEX</span> </div>

 

[elemental]

Like many others here, I also am not a physicist, but I am a thinker (to quote Glenn Beck : ). Anyway, what if the observed red shifts were due to something other than recession?<br /><br />As the four fundamental forces of nature are not yet united in an accepted Grand Unified Theory (GUT), partly due to our less than perfect understanding of gravity, perhaps the explanation for the greater redshifts of more distant galaxies is due to some kind of gravitational effect dilating the wavelength of the em radiation as it streams toward us.<br /><br />Since we do not have a solid grasp of gravity, but we do assert that it's influence is "astronomical" in nature (i.e. every particle in the universe is gravitationally connected to every other particle). If this is so, then would we not have an immensely complex and far-reaching grid of gravitational influence strewn throughout the universe. <br /><br />Is it not possible that, as light streams toward us, this gravitational matrix imparts some type of drag on the light and stretches the waves toward the red?<br /><br />The farther away a galaxy is, the greater is the time the light would be moving through this great matrix, therefore the greater the influence and thus the greater the red shift would be.<br /><br />I know the thought of a static universe sends chills up the spines of many, but anyway, it's just a thought.

 

[alokmohan]

There are two types of redshift,Doppler shift and gravitational red shift.Both are due to recession .No other possibility.

 

[elemental]

I agree that recession will cause red shift, but am not convinced that recession is the cause of the red shift we observe between us and distant galaxies. I am convinced that one day we will be offered an alternate explanation that will fit the GUT. Just as Copernicus and Galileo offered a better alternative to Ptolemy and Aristotle.<br /><br />Also, your suggestion that gravitational red shift is caused by recession is incorrect. Gravitational red shift occurs when a light source is in proximity to a significant gravitational field. It's apparent wavelength is reddened by the field, not by recession.

 

[derekmcd]

Actually, there are 3. Doppler, Expansion, and Gravitational.<br /><br />Doppler and expansion are similar in that they are related to objects receding from us. How they are receding from us is what differentiates the two, however. Two different mechanisms for the recession.<br /><br />Gravitational redshift come from a light source generated in high gravity being observed at a point that is in a much lower gravity well. <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[derekmcd]

I should finish reading posts before responding <img src="/images/icons/smile.gif" />. You already caught it. <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[SpeedFreek]

Just to bring the thread back to the OP<br /><br /><i><font color="yellow">"I have one question on this expanding universe thing.<br /><br />If we observe an object 14 billion lyrs away it seems to be going away faster than an object 7 billion lyrs away.<br /><br />Why do scientists believe this is evidence that the universe's expansion is accelerating? The light from the distant object is 14 billion years old. That means that it was moving away faster 14 billion years ago. The closer object's light is younger and moving slower.<br /><br />What is to say that the distant object is going the same speed as the closer object in real time and the only reason it appears to be going faster is because of the time lag? Maybe our view of it appears faster 'cause it is coming from an older, more rapidly expanding universe."</font>/i><br /><br />As I stated earlier, the idea that the expansion is accelerating doesn't come from the idea that objects further away are receding faster than closer ones. Your instincts here are indeed correct.<br /><br />We do indeed think they are receding faster, due to the fact that we are observing an older, more rapidly expanding universe.<br /><br />The only evidence we have of a recent acceleration of the expansion is the unexpected results we got when we looked at the apparent magnitude of certain supernovae.</i> <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

 

[vandivx]

<blockquote><font class="small">In reply to:</font><hr /><p>Since we do not have a solid grasp of gravity, but we do assert that it's influence is "astronomical" in nature (i.e. every particle in the universe is gravitationally connected to every other particle). If this is so, then would we not have an immensely complex and far-reaching grid of gravitational influence strewn throughout the universe.<br /><br />Is it not possible that, as light streams toward us, this gravitational matrix imparts some type of drag on the light and stretches the waves toward the red?<br /><br />The farther away a galaxy is, the greater is the time the light would be moving through this great matrix, therefore the greater the influence and thus the greater the red shift would be.<br /><p><hr /></p></p></blockquote><br /><br />google 'tired light hypothesis'<br /><br />vanDivX <div class="Discussion_UserSignature"> </div>

 

[ihwip]

It is my firm belief that we really won't know anything until we can make bipolar observations on a massive scale.<br /><br />What we really need to do is start thinking about sending a probe at an extremely high velocity with a vector that will possibly bring it to the Centauri system. This will allow us to have complete precision of how light interacts at vast distances and high velocities.<br /><br />A perfect example of this is the Voyager probes. Wasn't one of them too far away for what we should be observing or something like that?<br /><br />Until we can make a controlled observation there is just no way we can guarantee the accuracy of our views of the cosmos. Even then, things could be skewed a little. 100% accuracy is probably impossible.

 

[alokmohan]

I will not live for million years to see that .Sorry.

 

[elemental]

Don't lose hope altogether. Consider a probe travelling at 30,000 mph (not taking into account any slingshot assistance from Jupiter), quick calculations show we could have a probe there in ~100,000 years. Then, of course, we'd have to wait the 4.5 year return trip for any signal we send back from the probe to earth. It's a long time, I know, but it's not 5 million years. How long you say you expected to live?

 

[ihwip]

Well all is not for naught. Even if the probe was not all 4.5lys away we could still benefit from it while it is in transit, constantly beaming back info. We could learn from the time lag itself. The science and understanding we would get from a large probe would be immediate.

 

[elemental]

Yes, well...it was all just a little tongue-in-cheek. But I agree we may be able to gain something from it if we were able to increase the speed to at least some # of thousands of mps rather than mph to reap any benefit.

 

[gpbrainard]

HOW ARE YOU DOING YOU DONT KNOW ME BUT I LIK TO MEET PEOPLE IN OUR NEWTON WORLD IN WHICH THEIR WILL BE A TRANSMITION OF IQ KNOWHA <br /> PLES I WANT YOU TO FEED ME BACK

 

[alokmohan]

We are gong off topic.

 

[theone]

Since i have read THE FINAL THEORY book my every problem or phenomenon is solved now so if you can read that book i hope it will solve the problem