Tim_Lou Posted September 6, 2004 Report Posted September 6, 2004 ive recently viewed a show on the tv saying that there is something called "dark energy" causing the universe to expand faster and faster.something like anti-gravity...what are the possibility of this energy? if gravity is simply a time curve, would it be possible that this dark energy is also a "curve"??? edit: i found a web page describing dark energy:http://universe.gsfc.nasa.gov/science/darkenergy.html so, a vacume is full of rejecting energy???
BlameTheEx Posted September 7, 2004 Report Posted September 7, 2004 Tim That link doesn't work. The page is there, but you accidentally added a break to the end of it. I have to confess I made the same mistake in one of my posts. "Dark Energy" is certainly respectable at the moment, but I have some slight doubts. It seemed essential to salvage the Big Bang theory when the universes expansion was shown not to follow the script (the expansion appears to be speeding up). However I am not sure it can be called an explanation, more a matter of giving a name to our ignorance. Personally, it feels like a fudge. As long as no convincing explanation comes up for Dark Energy, I reckon there is as good a case for rethinking the whole explanation for the observed expansion. While I am sure to be in a minority group here, I am perhaps not alone in my doubts: "This starts to look incredibly ugly and complicated," says Mario Livio of the Space Telescope Science Institute. "I even wonder if we are we asking right questions." That is from a rather good article on Dark Energy here: http://www.space.com/scienceastronomy/generalscience/darkenergy_folo_010410.html
Bo Posted September 7, 2004 Report Posted September 7, 2004 The main idea behind Dark energy (which has nothing to do with dark matter!) is the following.After the big bang the universe expanded fast ('inflation', see my post somehere in the cosmology section) but this expension was counteracted by the gravitational pull of all the matter. So the fast expension should be slowed down. Measurements in 1998 or so provided proof on the other hand that the universe was accelarating. This means that there is some force pushing the universe apart. Since the strong and weak forces only are effective on very short scales, the electromagnetic force is in avarage zero (the universe has no total charge) and the gravitational force (as we know it) only attracts, there has to be something else. This has been dubbed dark energy.What can it be? (i'll be a bit short, i have to leave in 4 minutes...)- Einsteins laws permit gravity also to be repulsive. It could be that on very large scales gravity works also in a repulsive way.- The vacuum could have certain properties that 'effectively' works as a pushing force.- Gravity could 'leak away' to extra dimensions. Also this gives effectively gravity a small pushing part.- the compactification of string theory (going from 10 to 4 dimensions) gives rise to fields that effectively work as a pushing force.- None of the above
Freethinker Posted September 7, 2004 Report Posted September 7, 2004 Originally posted by: BlameTheExThat link doesn't work. The page is there, but you accidentally added a break to the end of it. I have to confess I made the same mistake in one of my posts.I think it is the site's parser that does that."Dark Energy" is certainly respectable at the moment, but I have some slight doubts. It seemed essential to salvage the Big Bang theory when the universes expansion was shown not to follow the script (the expansion appears to be speeding up).I love your continual attempt to pretend the Scientific community has a problem in or with the BB. It is so cute! So totally erroneous, but cute! There is nothing about an increase in the expansion rate that bothers the BB in the least. Since the BB was first developed out of extensive evaulation of gathered facts, one of the next questions was whether it was going to continue to expand or ultimately stop expanding and start contracting. We found that it's expansion was accelerating. OK. It's accelerating. Show us why that is so harmful to the theory of the BB that it required being "salvaged".However I am not sure it can be called an explanation, more a matter of giving a name to our ignorance.You hit this one on the head! We discovered that the expansion rate was increasing. We needed to discuss and set up propositions for that new knowledge. New knowledge ALWAYS leads to more ignorance. We learn that we din;t know something and now we need to learn more, and more, and more. The feeble mind would grasp at ignorance with fear and based on superstition "give it a name" GOD! The intellectuall approach is to avoid such stop gap (god of the gaps) filling nosnesne and research factual answer. Personally, it feels like a fudge.Ah so now you can FEEL dark energy? Incredible. As long as no convincing explanation comes up for Dark Energy, I reckon there is as good a case for rethinking the whole explanation for the observed expansion. While I am sure to be in a minority group here, I am perhaps not alone in my doubts:I asked once already above. I doubted that you would actually give any factual answers as you never do on other discussions, but I will state the question again here. Show us why that is so harmful to the theory of the BB that it required being "salvaged"."This starts to look incredibly ugly and complicated," says Mario Livio of the Space Telescope Science Institute. "I even wonder if we are we asking right questions."And I love how you take the singular quote that shows concern while the vast majority were shown as it being a "New ocean of discovery". And it was an old story you drug up from when the discovery first hit. How typically disingenuous of you.
Tormod Posted September 7, 2004 Report Posted September 7, 2004 Originally posted by: BlameTheExThat link doesn't work. The page is there, but you accidentally added a break to the end of it. I have to confess I made the same mistake in one of my posts. It's a pain - the parser occasionally adds a BR tag after the link and I have no way to fix it except report it to the forum software developers.
Freethinker Posted September 7, 2004 Report Posted September 7, 2004 Originally posted by: BoThe main idea behind Dark energy (which has nothing to do with dark matter!) is the following.....- None of the above And that is the beauty of the Scientific approach to knowledge. We are not forced to find ways to fit ridgid theological revelations into factual discoveries. At any point that it would be shown most benefitial, we can throw it all out and start over. But in general we have found our basic foundation of physics to be reasonably accurate and we are merely learning greater detail.
Bo Posted September 7, 2004 Report Posted September 7, 2004 hmm read today some things on the ekpyrotic scenario (don't know exaclty anymore what it was; i dont have my stuff here at home... it was also called 'the big clash'). The main idea was that if you smash 2 universes together; in the middle a new one comes to existence, which wouldn't need inflation of space or dark energy, but still have the desired properties.I think this is qualified as 'none of the above' ps i hope to know more on this subject soon so i'll might inform you Bo
Tim_Lou Posted September 7, 2004 Author Report Posted September 7, 2004 this dark energy sounds like the 2nd law of thermodynamics....
BlameTheEx Posted September 8, 2004 Report Posted September 8, 2004 Freethinker Edit you post to cut out the abuse and I will reply.
Uncle Martin Posted September 8, 2004 Report Posted September 8, 2004 Blame,I see in FT's post some sarcasm and dark humor,... but no abuse. We accept and deal with your "style" of posting,... I think it only fair that you try to do the same. IMHO
BlameTheEx Posted September 8, 2004 Report Posted September 8, 2004 Uncle My apologies but answering is optional. I will accept that your correction that sarcasm is not abuse, however I happen not to enjoy sarcasm. Others choose whether they answer me, and I will exercise the same right. I do have a more reasoned explanation for my point of view, and will share it when anybody asks me in a way that makes me want to share it.
Bo Posted September 8, 2004 Report Posted September 8, 2004 Tim wrote: this dark energy sounds like the 2nd law of thermodynamics....Could you explain that? Bo
Freethinker Posted September 8, 2004 Report Posted September 8, 2004 Originally posted by: BlameTheExI do have a more reasoned explanation for my point of view, and will share it when anybody asks me in a way that makes me want to share it.Your history shows that you don't provide facts when asked for them. And now you want me to appoligize for replying to you in a fashion promoted by your historical precedence? And let's not allow the benefit of your "more reasoned explanation" to any others lest I do? If you had a "more reasoned explanation", why is it neccesary that someone here beg for it before you will give it? Even further, why would you then obviously have choosen to give your "LESS reasoned explanation" in the first place? You love to make claims and ignore request for proof. I have once more attempted to elicit a post from you that fits the model that is accepted standard here. I have asked you to PROVE your claims. We should not have to pry proof from you every time you post a claim. Do you have any or not? Show us why that is so harmful to the theory of the BB that it required being "salvaged". You stated it. Can you stand behind it or just whine because I asked you to?
BlameTheEx Posted September 8, 2004 Report Posted September 8, 2004 Freethinker Hm. You have left out sarcasm only to suggest I whine. As to my history, well, You have a history of requesting explanations for sentences that can be got by reading their context, and sarcasm. Hence my tendency not to reply to you. Maybe others put up with your behaviour, but there is nothing in the F.A.Q that says I have to reply if I don't want to. You don't have to beg, and you don't have to apologise. I have asked for nether, although an apology would be nice. All you have to do is ask sensible questions politely. As for your demands for proof, don't be ridiculous. Had I made any claims here you could demand proof. I have done no such thing. I offered opinions. I didn't even pretend they were popular. As such I offered the reasoning behind my opinions, not proof. However as you have not asked for that here, it will have to wait for somebody who wants it. Perhaps nobody will. The reasoning would be self evident to most. As for my use of the word salvage. Theories stand or fall on the evidence. The evidence now appears to be that our universe is expanding, and that that expansion is accelerating. The BB theory, AS STANDS, results in no such acceleration, and that is no minor thing. It was created to explain the expansion of the universe and has failed. Now that to me justifies the use of the word "salvage". If it doesn't to you then I guess we will have to disagree. Regardless this is another one of your quibbles, and I make no promise to waste more time over them. You are not attempting to improve anybody's understanding of science here, just getting your kicks by being obnoxious.
Freethinker Posted September 8, 2004 Report Posted September 8, 2004 Originally posted by: BlameTheExFreethinker... Yada yada... Still no facts. Or no suprise that there isn't.
Tim_Lou Posted September 8, 2004 Author Report Posted September 8, 2004 Originally posted by: BoTim wrote: this dark energy sounds like the 2nd law of thermodynamics.... Could you explain that? Bo i think that the expension of the universe seems like a tendency rather than a force, just like the law of thermodynamics.... well, just a thought... or maybe like gravity, its simply an opposite curve in the space....oh, i dont know...
Tormod Posted September 8, 2004 Report Posted September 8, 2004 Originally posted by: BlameTheExThe BB theory, AS STANDS, results in no such acceleration, and that is no minor thing. Blame, this is most certainly a claim which warrants proof. My apologies for not going back to read all the posts from other threads (I have a lot of posts to catch up with lately) but as far as I know the current mainstream big bang theory neither predicts nor denies this accelleration. Your phrasing is a bit strange (a theory does not "result in" any physical event) but I assume you mean "predicts". The inflationary theory is what I expect to lie at heart in the acceleration of the expansion rate.
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