Is Dark Energy a Relatively Recent Force?

connor240287 · Oct 14, 2008

I May Only be 13 but I Have a Quite Sophisticated Question,(Sophisticated to me) Hope You Guys Can Answer it. I've read that dark energy is the energy driving the accelerated expansion of the universe. Its density doesn't decrease as space increases. So, does this mean that it has existed with equal density from the beginning of the universe? Have scientists found that the accelerationed expansion of the universe was first decresing, and has started to increase more "recently"?  <div class="Discussion_UserSignature"> ________________________________________________________ <img id="29efa0bc-ee02-404c-85eb-334f93c8d80a" src="http://sitelife.space.com/ver1.0/Content/images/store/9/5/29efa0bc-ee02-404c-85eb-334f93c8d80a.Large.jpg" alt="blog post photo" width="101" height="105" /> <img id="c1f1f498-9f76-47c7-9c87-d9a97a718bf0" src="http://sitelife.space.com/ver1.0/Content/images/store/1/12/c1f1f498-9f76-47c7-9c87-d9a97a718bf0.Large.jpg" alt="blog post photo" width="110" height="105" /> <img id="5738f0e8-a5bf-4d61-81ea-d5e2dfd8d180" style="width:116px;height:105px" src="http://sitelife.space.com/ver1.0/Content/images/store/7/1/5738f0e8-a5bf-4d61-81ea-d5e2dfd8d180.Large.jpg" alt="blog post photo" width="115" height="103" /> <img id="b10b0206-6c43-4de0-bf20-9974898a23e8" style="width:119px;height:105px" src="http://sitelife.space.com/ver1.0/Content/images/store/1/15/b10b0206-6c43-4de0-bf20-9974898a23e8.Large.jpg" alt="blog post photo" width="119" height="103" /> </div>

MeteorWayne · Oct 15, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>I May Only be 13 but I Have a Quite Sophisticated Question,(Sophisticated to me) Hope You Guys Can Answer it. I've read that dark energy is the energy driving the accelerated expansion of the universe. Its density doesn't decrease as space increases. So, does this mean that it has existed with equal density from the beginning of the universe? Have scientists found that the accelerationed expansion of the universe was first decresing, and has started to increase more "recently"?  Posted by connor240287</DIV> Good question, welcome to Space.com!!What you have stated is correct as far as we understand it now. Dark Energy has always been there. The expansion of the Universe started with the big bang. Dark energy was adding to the acceleration. Originally, when the Universe was much smaller, the gravitation of all the matter so close slowed the Big Bang acceleration, but as the matter has spread out, the gravitational pull has diminished, so the residual acceleration from dark energy is now increasing the expansion again.That's about the latest according to current observations and theory.Hope that helps. Wayne <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

connor240287 · Oct 15, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Good question, welcome to Space.com!!What you have stated is correct as far as we understand it now. Dark Energy has always been there. The expansion of the Universe started with the big bang. Dark energy was adding to the acceleration. Originally, when the Universe was much smaller, the gravitation of all the matter so close slowed the Big Bang acceleration, but as the matter has spread out, the gravitational pull has diminished, so the residual acceleration from dark energy is now increasing the expansion again.That's about the latest according to current observations and theory.Hope that helps. Wayne Posted by MeteorWayne</DIV> Thanks For Welcomeing Me MeteorWayne.And Thanks For Answering My Question. <div class="Discussion_UserSignature"> ________________________________________________________ <img id="29efa0bc-ee02-404c-85eb-334f93c8d80a" src="http://sitelife.space.com/ver1.0/Content/images/store/9/5/29efa0bc-ee02-404c-85eb-334f93c8d80a.Large.jpg" alt="blog post photo" width="101" height="105" /> <img id="c1f1f498-9f76-47c7-9c87-d9a97a718bf0" src="http://sitelife.space.com/ver1.0/Content/images/store/1/12/c1f1f498-9f76-47c7-9c87-d9a97a718bf0.Large.jpg" alt="blog post photo" width="110" height="105" /> <img id="5738f0e8-a5bf-4d61-81ea-d5e2dfd8d180" style="width:116px;height:105px" src="http://sitelife.space.com/ver1.0/Content/images/store/7/1/5738f0e8-a5bf-4d61-81ea-d5e2dfd8d180.Large.jpg" alt="blog post photo" width="115" height="103" /> <img id="b10b0206-6c43-4de0-bf20-9974898a23e8" style="width:119px;height:105px" src="http://sitelife.space.com/ver1.0/Content/images/store/1/15/b10b0206-6c43-4de0-bf20-9974898a23e8.Large.jpg" alt="blog post photo" width="119" height="103" /> </div>

DrRocket · Oct 15, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Good question, welcome to Space.com!!What you have stated is correct as far as we understand it now. Dark Energy has always been there. The expansion of the Universe started with the big bang. Dark energy was adding to the acceleration. Originally, when the Universe was much smaller, the gravitation of all the matter so close slowed the Big Bang acceleration, but as the matter has spread out, the gravitational pull has diminished, so the residual acceleration from dark energy is now increasing the expansion again.That's about the latest according to current observations and theory.Hope that helps. Wayne Posted by MeteorWayne</DIV>Dark energy is also recent in a different sense.  Until the late 1990's it was generally believed that the effect of gravity caused by the mass in the universe was causing the acceleration to slow dowm.  It was not until the observations of type 1A supernovas that the concensus became that expansion was in fact accelerating.  So until that time there was no need for the hypothesis of dark energy.Dark energy is still not very well understood, to say the least. <div class="Discussion_UserSignature"> </div>

MeteorWayne · Oct 15, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Dark energy is also recent in a different sense.  Until the late 1990's it was generally believed that the effect of gravity caused by the mass in the universe was causing the acceleration to slow dowm.  It was not until the observations of type 1A supernovas that the concensus became that expansion was in fact accelerating.  So until that time there was no need for the hypothesis of dark energy.Dark energy is still not very well understood, to say the least. Posted by DrRocket</DIV> However, I believe the current interpration of the data is that the dark energy effect is still there early in the Univers' history, it's just that it was overwhelmed by gravity so was too small to detect unless you were looking for it. Also, measurements were too imprecise even a decade ago to make such a subtle determination. It has been there all along, but was only discovered recently when measurements allowed such precise determinations of the effect.And even today, the effect is very small within a sea of large error bars.As you say, it is not very well understood, considering it's only been suspected for a decade, and we have no clue as to what it is. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

tampaDreamer · Oct 15, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>However, I believe the current interpration of the data is that the dark energy effect is still there early in the Univers' history, it's just that it was overwhelmed by gravity so was too small to detect unless you were looking for it. Also, measurements were too imprecise even a decade ago to make such a subtle determination. It has been there all along, but was only discovered recently when measurements allowed such precise determinations of the effect.And even today, the effect is very small within a sea of large error bars.As you say, it is not very well understood, considering it's only been suspected for a decade, and we have no clue as to what it is. Posted by MeteorWayne</DIV>Not to jump beyond my knowledge, but it could just as easily be that dark energy is a placeholder for our misunderstanding of the known forces of the universe, rather than a new force.  Whereas dark matter has a pretty solid explanation (matter than is not radiating), dark energy is pretty much a total mystery. <div class="Discussion_UserSignature"> </div>

MeteorWayne · Oct 15, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Not to jump beyond my knowledge, but it could just as easily be that dark energy is a placeholder for our misunderstanding of the known forces of the universe, rather than a new force.  Whereas dark matter has a pretty solid explanation (matter than is not radiating), dark energy is pretty much a total mystery. Posted by tampaDreamer</DIV> But it's effect seems to clearly show in the expansion speeds in the Universe, so must ba accounted for. Hence the "dark energy" moniker. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

DrRocket · Oct 15, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Not to jump beyond my knowledge, but it could just as easily be that dark energy is a placeholder for our misunderstanding of the known forces of the universe, rather than a new force.  Whereas dark matter has a pretty solid explanation (matter than is not radiating), dark energy is pretty much a total mystery. Posted by tampaDreamer</DIV>You are correct.   Both are placeholders for phenomena that seem to be real but for which there is not a concrete explanation.There seems to be some observational evidence for dark matter, and some modeling evidence in the form of fits to a dark matter distribution consistent with the resulting gravity being able to model galactic rotational rates.  But there is no good, verified explanation for what it is.Dark energy is even more mysterious.  It can be modeled as a cosmological constant in the Einstein field equations for general relativity.  There is however, no good explanation beyond that -- for instance what it could be.  Known forms of matter and energy provide gravitational attraction, while dark energy and its reflection in a cosmological constant represent repulsion.  If this is a misunderstanding of the known forces, and I guess that it could be, then it is a substantial misunderstanding, since those forces would seem to point in the wrong direction.  The bottom line is that physics is still a research discipline.  We know quite a bit, but we don't know everything.  Mysteries like "dark matter" and "dark energy" are one reason why research in physics is interesting and challenging. <div class="Discussion_UserSignature"> </div>

connor240287 · Oct 15, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>You are correct.   Both are placeholders for phenomena that seem to be real but for which there is not a concrete explanation.There seems to be some observational evidence for dark matter, and some modeling evidence in the form of fits to a dark matter distribution consistent with the resulting gravity being able to model galactic rotational rates.  But there is no good, verified explanation for what it is.Dark energy is even more mysterious.  It can be modeled as a cosmological constant in the Einstein field equations for general relativity.  There is however, no good explanation beyond that -- for instance what it could be.  Known forms of matter and energy provide gravitational attraction, while dark energy and its reflection in a cosmological constant represent repulsion.  If this is a misunderstanding of the known forces, and I guess that it could be, then it is a substantial misunderstanding, since those forces would seem to point in the wrong direction.  The bottom line is that physics is still a research discipline.  We know quite a bit, but we don't know everything.  Mysteries like "dark matter" and "dark energy" are one reason why research in physics is interesting and challenging. Posted by DrRocket</DIV> I Dont Mean to Interrupt You, But I Have Thought off Sumthing And I Took Ideers Etc From a Cuple off Your Sentences.According to Current Theories Dark Energy has Always Been Around and has Always Exerted the Same Force. However, in the Early Universe, Matter was Closer Together and the Effects of Gravity Caused the Expansion of the Universe to Slow Down. About 5 billion Years ago, the Density of Matter (Both Normal Matter and Dark Matter), Which had Been Decreasing Since the Big Bang, Became low Enough That the Dark Energy was able to Start Accelerating the Expansion of the Universe.  Tell me if I'm Right or Rong, As I Said I am Only 13 Years Old. >< <div class="Discussion_UserSignature"> ________________________________________________________ <img id="29efa0bc-ee02-404c-85eb-334f93c8d80a" src="http://sitelife.space.com/ver1.0/Content/images/store/9/5/29efa0bc-ee02-404c-85eb-334f93c8d80a.Large.jpg" alt="blog post photo" width="101" height="105" /> <img id="c1f1f498-9f76-47c7-9c87-d9a97a718bf0" src="http://sitelife.space.com/ver1.0/Content/images/store/1/12/c1f1f498-9f76-47c7-9c87-d9a97a718bf0.Large.jpg" alt="blog post photo" width="110" height="105" /> <img id="5738f0e8-a5bf-4d61-81ea-d5e2dfd8d180" style="width:116px;height:105px" src="http://sitelife.space.com/ver1.0/Content/images/store/7/1/5738f0e8-a5bf-4d61-81ea-d5e2dfd8d180.Large.jpg" alt="blog post photo" width="115" height="103" /> <img id="b10b0206-6c43-4de0-bf20-9974898a23e8" style="width:119px;height:105px" src="http://sitelife.space.com/ver1.0/Content/images/store/1/15/b10b0206-6c43-4de0-bf20-9974898a23e8.Large.jpg" alt="blog post photo" width="119" height="103" /> </div>

MeteorWayne · Oct 15, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'> I Dont Mean to Interrupt You, But I Have Thought off Sumthing And I Took Ideers Etc From a Cuple off Your Sentences.According to Current Theories Dark Energy has Always Been Around and has Always Exerted the Same Force. However, in the Early Universe, Matter was Closer Together and the Effects of Gravity Caused the Expansion of the Universe to Slow Down. About 5 billion Years ago, the Density of Matter (Both Normal Matter and Dark Matter), Which had Been Decreasing Since the Big Bang, Became low Enough That the Dark Energy was able to Start Accelerating the Expansion of the Universe.  Tell me if I'm Right or Rong, As I Said I am Only 13 Years Old. >< Posted by connor240287</DIV> You are correct. However, your deliberate misspelling (which was not displayed in your first post) makes me suspicious that you are not who you seem. When I was 13, I could spell just fine. I still can. I type really lousy, though.I don't know what you are setting up, but in your dozen posts you have gone from an intelligent person to someone who can't spell "cat" correctly. I am beginning to wonder what your game is.So far some of your posts have remained very intelligent. Others have been gibberish.Please make more of an effort to spell correctly, since it seemed to be within your ability before. It gave you credibility. Don't waste that. Just friendly advice. <div class="Discussion_UserSignature"> But the Krell forgot one thing John. Monsters. Monsters from the Id. I really, really, really, really miss the "first unread post" function </div>

connor240287 · Oct 15, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>You are correct. However, your deliberate misspelling (which was not displayed in your first post) makes me suspicious that you are not who you seem. When I was 13, I could spell just fine. I still can. I type really lousy, though.I don't know what you are setting up, but in your dozen posts you have gone from an intelligent person to someone who can't spell "cat" correctly. I am beginning to wonder what your game is.So far some of your posts have remained very intelligent. Others have been gibberish.Please make more of an effort to spell correctly, since it seemed to be within your ability before. It gave you credibility. Don't waste that. Just friendly advice. Posted by MeteorWayne</DIV> Ok, Thanks For The Advice MeteorWayne.I'll Take That into Mind and Not Rush Things. {i.e Spelling}  <div class="Discussion_UserSignature"> ________________________________________________________ <img id="29efa0bc-ee02-404c-85eb-334f93c8d80a" src="http://sitelife.space.com/ver1.0/Content/images/store/9/5/29efa0bc-ee02-404c-85eb-334f93c8d80a.Large.jpg" alt="blog post photo" width="101" height="105" /> <img id="c1f1f498-9f76-47c7-9c87-d9a97a718bf0" src="http://sitelife.space.com/ver1.0/Content/images/store/1/12/c1f1f498-9f76-47c7-9c87-d9a97a718bf0.Large.jpg" alt="blog post photo" width="110" height="105" /> <img id="5738f0e8-a5bf-4d61-81ea-d5e2dfd8d180" style="width:116px;height:105px" src="http://sitelife.space.com/ver1.0/Content/images/store/7/1/5738f0e8-a5bf-4d61-81ea-d5e2dfd8d180.Large.jpg" alt="blog post photo" width="115" height="103" /> <img id="b10b0206-6c43-4de0-bf20-9974898a23e8" style="width:119px;height:105px" src="http://sitelife.space.com/ver1.0/Content/images/store/1/15/b10b0206-6c43-4de0-bf20-9974898a23e8.Large.jpg" alt="blog post photo" width="119" height="103" /> </div>

R1 · Oct 15, 2008

here is a video I liked on dark energy and the runaway universe:http://www.youtube.com/watch?v=vPkGEVgOJK0&feature=related(edited spelling)   <div class="Discussion_UserSignature"> </div>

DrRocket · Oct 15, 2008

Replying to: <DIV CLASS='Discussion_PostQuote'>Ok, Thanks For The Advice MeteorWayne.I'll Take That into Mind and Not Rush Things. {i.e Spelling}  Posted by connor240287</DIV>Nobody really understands dark energy (or dark matter).  But here are some sources traceable to real scientists that try to explain what is know, what is suspected and why.  The level of sophisticatin varies from little to quite a lot, so don't be discouraged if you cannot follow some of it.http://brahms.phy.vanderbilt.edu/a102/handouts/lecturenotes/20061113.pdfhttp://scientificcuriosity.blogspot.com/2007/11/laymans-tutorial-to-dark-side-i.htmlhttp://imagine.gsfc.nasa.gov/docs/science/mysteries_l1/dark_energy.htmlhttp://supernova.lbl.gov/~evlinder/weinberg.pdfhttp://supernova.lbl.gov/~evlinder/sci.htmlhttp://csep10.phys.utk.edu/astr162/lect/cosmology/darkmatter.htmlhttp://astro.berkeley.edu/~mwhite/darkmatter/dm.html <div class="Discussion_UserSignature"> </div>

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