life out there?
Discussion
ash73 said:
More interesting is the alternative theory "tired light" suggested by Fritz Zwicky
https://en.m.wikipedia.org/wiki/Tired_light
Not really.https://en.m.wikipedia.org/wiki/Tired_light
When theory doesn't match observation then it's almost certainly time to abandon the theory.
From that article
"Despite periodic re-examination of the concept, tired light has not been supported by observational tests and has lately been consigned to consideration only in the fringes of astrophysics"
ash73 said:
The tired light theory is interesting (to me) because its rejection provides context.
Of course, the dark energy mathematical bodge is just fine
This area of physics deals with equations to fit observations and then making attempts to disprove them. How is this more a "bodge" than say, the recently vindicated Higg's boson? Of course, the dark energy mathematical bodge is just fine
It's been a while since I read it now but my understanding of Krauss's work on this is it's quite plausible. The big sticking point is the calculations which yield energy results which are massively too high for empty space, but it by no means disproves the theory just yet.
ash73 said:
It's a bodge because they just invented a new force to make existing theory fit observation, whereas Higgs integrated existing forces mathematically by explaining how mass worked.
But those "existing forces" were once new - and it's only through experimentation that they were confirmed.How do you know that won't be the case here too?
How do you know we have already discovered all of the forces and that there are no new ones out there. To say it's a "bodge" implies you know this to be true.
ash73 said:
I would expect expansion to increase in rate without any mysterious force[, because as more space is created that space in turn creates even more space, so it must be exponential. And as the space increases between them to infinity their gravitational attraction decreases to zero, so the universe does not need to collapse. In other words, there's no requirement for a dark energy force, except presumably it makes the maths work.
At what is this rate? And, if the expected rate was massively exceeded, would you be willing to accept it is possible energy had mysteriously been added? Then if we conducted theoretical experiments and then found this value (DE) was compatible with existing theories and hypotheses? Not only that it also matched existing observations?
It is a humble position of "we think this true" made from probably thousands of man hours. Very smart people dedicate their lives to this sort of thing, they don't just "fudge" numbers.
I mean Christ on a bike, the amount of marketing bulls
t people believe every day without question, I mean fking hell "anti-oxidants", "natural remedies", "nothing works faster", "organic", "clinically proven"... but when a group of distinguished scientists take decades to say "we believe DE exists but we're still working on it", they can be written off by some no mark by saying they have just "bodged" an equation.
ash73 said:
But that's not how expansion works, the objects aren't moving; space itself is expanding. Galaxies can't be "pushed" away from each other faster than light.
The objects are moving - away from the BB singularity as well as getting further apart due to space expanding. From what I've read the distance between us and some objects outside the observable universe is growing faster than C. IIRC the mathematics suggests that at some point in the future the observable universe would be limited to our gravitationally bound cluster of galaxies.Given we're part of a massive cluster of galaxies that are in a gravitational relationship will probably be used to calculate the strength of and repulsive forces vs gravity as measurements are taken. I'd be surprised if that hasn't already been done.
IainT said:
ash73 said:
But that's not how expansion works, the objects aren't moving; space itself is expanding. Galaxies can't be "pushed" away from each other faster than light.
The objects are moving - away from the BB singularity as well as getting further apart due to space expanding. From what I've read the distance between us and some objects outside the observable universe is growing faster than C. IIRC the mathematics suggests that at some point in the future the observable universe would be limited to our gravitationally bound cluster of galaxies.Given we're part of a massive cluster of galaxies that are in a gravitational relationship will probably be used to calculate the strength of and repulsive forces vs gravity as measurements are taken. I'd be surprised if that hasn't already been done.
FredClogs said:
I have a memory that from earth pov there is more blue shift than red shift observed by "near" objects, i.e more stuff is moving towards us than away from us.
That's make sense given galaxies all over are colliding! What I find fascinating is that they seem to pass through one another, come out the other side, slow down and repeat. I guess to eventually merge way in the future. Awesome stuffs.FredClogs said:
I have a memory that from earth pov there is more blue shift than red shift observed by "near" objects, i.e more stuff is moving towards us than away from us.
The ONLY objects heading towards us are the half dozen or so Galaxies that make up our (gravitationally bound) cluster and the contents therein. Everything else in the universe (ie The billions of other Galaxies) are heading away from us.ash73 said:
Calls to authority are unnecessary on a science forum; if you think I'm wrong go ahead and say why.
I've made no such thing. I asked you very deliberate questions first to try and help you get on the right track to understanding why you are mistaken a la the Socratic method. I also pointed out the claim you're making is a very arrogant one as you dismiss others based on apparent ignorance and no counter evidence of your own. It also has the familiar debasement of the work of many distinguished people which seems endemic on this forum. But ultimately, you can ignore my annotations and just answer the initial questions if you like. It doesn't impact my point one bit.
But just to make it crystal clear, I'm not challenging you to wind you up or saying you're wrong because of who you are, I'm trying to understand how you arrived at your conclusion, as you are not making sense to me.
mudflaps said:
FredClogs said:
I have a memory that from earth pov there is more blue shift than red shift observed by "near" objects, i.e more stuff is moving towards us than away from us.
The ONLY objects heading towards us are the half dozen or so Galaxies that make up our (gravitationally bound) cluster and the contents therein. Everything else in the universe (ie The billions of other Galaxies) are heading away from us.So you're both right.
Some of the nearer galaxies are indeed moving towards us. In fact, teh Andromeda Galaxy will actually collide with ours at some point.
This is because the galaxies exist in family clusters which orbit a common centre of gravity - so in each "local group" you will get some movement towards each other.
But overall, the CLUSTERS of galaxies are moving away from each other.
This is because the galaxies exist in family clusters which orbit a common centre of gravity - so in each "local group" you will get some movement towards each other.
But overall, the CLUSTERS of galaxies are moving away from each other.
ash73 said:
I've already provided a simple example. Read the last sentence, they took Einstein's cosmological constant, something he said was his greatest blunder, popped it on the other side of the equation and bingo it worked; and they have no idea why. That's a bodge.
Krauss talks about dark energy increasing in strength until even atoms fly apart. If space can create new space the expansion will accelerate geometrically, and the rate just is what it is; it doesn't make any difference locally.
The real question is how does space create new space, and where does the energy come from. The hoards of distinguished scientists spending years developing a perfect model have so far just given it a name. They might as well call it Barney the Bodge.
The last two things you said were "still nothing" (now deleted?) and "appeals to authority" before that you say that the rate is fine, only it isn't. The rate of expansion cannot be explained in the manner you're suggesting.Krauss talks about dark energy increasing in strength until even atoms fly apart. If space can create new space the expansion will accelerate geometrically, and the rate just is what it is; it doesn't make any difference locally.
The real question is how does space create new space, and where does the energy come from. The hoards of distinguished scientists spending years developing a perfect model have so far just given it a name. They might as well call it Barney the Bodge.
I have understood your point, and once again the rate is still too fast a rate to be accounted for without dark energy theories. We are left with two options, either DE (or a variant) is in effect, or Einstein's theory of gravity is wrong. The latter is incredibly hard to disprove as it simply works so well!
Einstein may have dubbed the cosmological constant his "greatest blunder", but many are saying it may be proven right after all. Let's not forget Einstein also similarly critical of his "Lens-Like Action of a Star by the Deviation of Light in the Gravitational Field", which has provided a way of detecting the presence of dark matter, so even the big man was not able to see the potential of his work sometimes.
ash73 said:
Prof Prolapse said:
the rate is still too fast a rate to be accounted for without dark energy theories
If there are 1000 "units" of space between us and a distant galaxy, how many new units of space are created each year? If each of those units can then create new units, at the same rate, the expansion must be exponential. It was never going to be linear. The actual rate of creation of new space is whatever it is, and can remain constant; where is the requirement for a growing repulsive force?
Perhaps those who describe dark energy as a force are interpreting expansion as stretching existing space, rather than creating new space? That's the kind of explanation I'm looking for.
Prof Prolapse said:
Einstein may have dubbed the cosmological constant his "greatest blunder", but many are saying it may be proven right after all.
Einstein believed the universe was static while his equations predicted it would collapse, so he introduced a fiddle-factor called the cosmological constant to maintain a steady state. Without it the universe would collapse exponentially under the influence of gravity; is it any surprise when you put the same constant on the other side of the equation it accounts for an exponential expansion? It's still a bodge because we don't understand it, yet. OK here's my understanding as to why you're barking up the wrong tree and someone feel free to dip in here as I am not claiming to be an expert.
Say I have many galaxies and I move them apart, all from one another, I must first overcome the gravitational attraction between them yes? Let's keep it simple and say I do so using momentum from the big bang, and in the gap, we have, empty space. More than we did before, I have expanded the universe.
Then let's say I do this on a universal scale and measure the acceleration. I have overcome gravity on a huge scale and the energy expenditure can be estimated by knowing just few basic data points. I then discover this the energy required to overcome gravity is hugely greater than the momentum of the big bang. Either gravity makes no sense, which is very unlikely given the huge amount of experimental and observational evidence, or energy is somehow being added.
So what you are saying about the expansion is true, in so much as it is happening. But what as I tried to explain to you in our first back and to, it is the rate which is the crux of the argument (not whether it is simply exponential or not!), as the energy required to achieve it cannot be obtained without the addition of energy, or the reduction of the cost. The latter being very very difficult to envision.
The cosmological constant is by the by in this discussion. The above would seem to complement it, but that does not advance the point only the narrative.
ash73 said:
Prof Prolapse said:
it is the rate which is the crux of the argument (not whether it is simply exponential or not!), as the energy required to achieve it cannot be obtained without the addition of energy, or the reduction of the cost.
If ones assumes the creation of new space requires energy, then obviously as the amount of space being created increases exponentially, at whatever rate, so will the energy requirement. They calculated the energy of empty space, extrapolated to include expansion, and concluded 70% of everything is dark energy, fine, but in reality we have no idea what it is or how it works.I did find a good summary here:
http://scienceblogs.com/startswithabang/2012/07/26...
article said:
If there’s an intrinsic energy to space, and it’s expanding (and therefore creating more space), aren’t we violating the conservation of energy? The answer is no, because dark energy doesn’t only have an energy density: it also has a negative pressure with very specific properties. As that negative pressure pushes outwards on space, it does negative work on the Universe, and the work it does is exactly equal to the increased mass/energy of whatever patch of space you’re looking at. I wrote a more technical explanation here last December, for those so inclined.
Perhaps Krauss is talking about this negative pressure when he predicts even atoms will eventually fly apart, who knows. I was just hoping someone could offer more detail, rather than needless tit for tat.Krauss is one of the leading proponents in DE and mentions this heavily in his book, it's called "a universe from nothing", and many of his lectures. As a stong advocate of dark energy he is demonstrating that dark energy principle does not violate certain natural laws.
"Needless tit for tat"? I'm trying to explain to you why you're lacking a basic grounding in what dark energy is despite your dismissal of it. I'm sorry but if you think we're debating or arguing you're mistaken.
ash73 said:
Prof Prolapse said:
I'm trying to explain to you why you're lacking a basic grounding in what dark energy is despite your dismissal of it.
There is nothing to dismiss. They don't understand it, you don't understand it, I don't understand it. Nobody knows what it is.Yes you may have to overcome gravitational attraction to insert new space, who knows, it's not at all clear how this mechanic works; what is the structure of space and how is it created? And one would assume energy is required to create new space, but for now they've fudged it to balance energy to zero with some dubious hypotheses.
Right, so now the sum zero energy of DE is "dubious" as well, bloody hell you had never even heard of it a few hours ago but now you can dismiss another equation, you're wasted here mate. You should be out there working with the cosmologists or theoretical physicists.
Look I'm done banging my head off a wall, but you've already picked up on Professor Krauss. He rights books for laymen like us. Just read one, I promise if you absorb what he has to say you'll find it very enlightening based on what you say.
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