The Pinetar Rag

January 29, 2013

Dark Energy solved?

Filed under: Canned Heat,Cosmology,Dark Energy,Physics,Random — mcgonnigle @ 11:52 pm

I’ve been reading Einstein’s bio on the commute to work. Naturally, that’s got me re-reading books like The Dancing Wu Li Masters and thinking about Relativity. It’s neat to think about. Sometimes, you can think you are really understanding it and then sometimes, it crumbles like a house of cards, so you re-read and try and build back up.

This has also led to some reading about Cosmology, because, as the readers know, I’ve been an armchair Cosmologist for 20 years now. And in those 20 years, the big breakthrough has been Dark Energy. Yes, I tried to explain it to my 5.5 year old–I thought I did a decent job.

But I had a thought about what the solution to Dark Energy is and it’s driving me nuts now. I am toobing up all sorts of lectures and videos trying to get answers, because, I am thinking, I CAN’T be right. So I just want to hear why what I’m thinking, ISN’T right. Make sense? I am joking with Mrs. Pinetar that I am going to win the Nobel Prize in Physics for this (I can think of a guy who won one who didn’t do diddly for it).

Dark Energy is not understood. It’s a placeholder to explain the observed acceleration of the farthest galaxies from us, as they speed away from us and everything else. The Universe is expanding at a more and more rapid rate, right? Easy. If all the stuff in the Universe was gravitationally tugging at everything else, we’d expect to see a DE-celeration, and yet we see the opposite. We don’t have a law of physics that explains that, so they said “it’s Dark Energy” and it’s either a repulsive force, or something else. And there are many theories and have not looked at them all, nor would I understand them all if I did.

But the instant they lay this problem out, I immediately think of this: Relativity-101. When things go very fast, “Relativistic speeds”, which is another way of saying, “a speed that is a fair fraction of the speed of light”; when things go very fast, they get heavier. They gain Mass. Mass is responsible for gravity.

When you read cosmology and they get to Hubble in the 1920′s, the first thing you read is that, “…the farther away the galaxy, the bigger the redshift” (Bigger redshift = faster speed away from us). So the galaxies on the edge of the expanding bubble are going the fastest, so then, due to Relativity, aren’t they also the heaviest? And if you’ve seen a curve of the equation, the curve is steep as you approach lightspeed, so the bump up in mass is going to go off the charts! (I’ll try and find a chart).

RelMass

This leads to a model whereby the edges of the expanding bubble are ridiculously heavy. Almost all the gravity in the universe should be concentrated at the extreme edge of the bubble. If it’s a gravity tug-of-war, then the edges are going to blow away the middle and wah-lah, the expansion rate will increase. There’s a nice, smoothly accelerating universe that uses the laws we already have proven out, thanks to Herr Einstein. You don’t need any dopey “Dark Energy”. You don’t need to make up new laws or repulsive forces.

Questions and assumptions about this? Sure, here goes:

This assumes that the galaxies furthest out are and always were, going the fastest. I think this is the view held. The opposite of this is that it’s only the space between things that’s expanding and since there’s simply more space between the further objects then they appear to be going faster.

#2 when an object is moving at relativistic speeds and therefore gains mass, does that mass warp space and create gravity? Or is it simply relative mass, or somehow, “virtual mass”? I think it’s true mass, but I don’t know.

There are other “questions” but these are two that stand out for me. I would need to find a physicist to answer them. I don’t know any.

How would I test my theory? Well, I think you could write a basic computer program to model a few thousand galaxies and give them the appropriate behavior for gravitational interaction as well as Relativistic “weight”. Play around with the starting parameters, speeds, etc., and see if you can’t get it to run and replicate a steadily expanding universe, like the one now posited (or observed, however you wish).

I haven’t read anything addressing my idea here so I tend to think that there’s something just basically wrong with it–something so fundamentally off about it, that it doesn’t merit a mention as a possible solution. And with all the uber-smart guys who get paid to do this stuff, I can’t imagine that something so basic would be overlooked.

I’m not saying I’m right or anything. What I’m really doing is asking, “WHY isn’t this valid?”. I want to know what would invalidate this line, and I haven’t read anything that does…yet. And I haven’t read much, so that’s not even a big shocker.

This is a perfect example of why I like armchair Cosmology: because you can do these kind of thought experiments and you can often follow along with the big boys and get all wrapped up in something like this. And sure, while you can’t do the x’s and o’s “science”, you can follow along at 30,000 feet.

So I’m throwing it out to the readers. Does anyone know a physicist? Can we get some clarification? Whoever it is, they can have the idea, just put my name somewhere on the paper and give me a couple G’s of the prize money if we win big in Stockholm.

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4 Comments »

  1. A couple thoughts on the drive in: We do have a regular reader of The Rag who is a PHD in Mircrobiology, so maybe he can lead us to guys who can comment.
    Thoughts about the computer model. They do these all the time to model gravity and systems; galaxies, superclusters, etc. So somewhere, the work has been done. If I was writing the code myself? I don’t know whether you’d do it as a single thread or multi-threaded. Maybe JW can comment. If you modelled a 1000 galaxy universe, then at every time point T, you’d have to calculate every point’s gravitational attraction to every other point, so that’s 1000×1000, or 1,000,000 million gravity calcs per slice of time. And, you’d have to track each galaxy’s speed and direction and relativistic weight and you’d have to do that before calc’ing the 1 million forces. If I want to do a time slice every year and run a few billion years (circa 10-20) of evolution, that’s now a 20 billion x 1 million calcs for the CPU’s. So, developing this, with bugs and what not–is not trivial. I guess you could make it more lumpy by calculating at points 1000 years apart. And doing something like this rests on the idea that all of my assumptions are correct, and I have no idea of that–like I said, I haven’t read anything re that which makes me think that they’re not valid. Oh well. Onward.

    Comment by mcgonnigle — January 30, 2013 @ 11:02 am | Reply

  2. There is one more big component to this stuff and that is “Gravity Waves”. How does gravity propagate? Does it propagate at the speed of light? I think this is up in the air right now. They are trying to detect gravity waves (http://www.ligo.caltech.edu/LIGO_web/PR/scripts/facts.html). The implications are big. If my dopey theory has merit, then, it would have to be in the model; in other words, if the edge galaxies get relativistically very heavy, how long and how far is that heaviness (extra gravitational tug on other galaxies) felt? If it’s only the speed of light and not instantaneous, then it would favor the outter edge of the expanding bubble. Is that what we observe and measure? So if you’re a physicist and weighing in on this, we want to know about this too.

    Comment by mcgonnigle — January 30, 2013 @ 11:40 am | Reply

  3. Here’s the possible answer to the whole thing and it’s as I suspected. The universe isn’t expanding but stetching, and in that model, I don’t think there’s any relativistic weight gain as I have described. Game, Set, Match. :

    The whole piece is here and it’s well written:
    http://curious.astro.cornell.edu/question.php?number=274

    Here’s a snip:

    Let me begin by saying that “expanding” isn’t really the best word to describe what is happening to the universe, although that is the word that is often used – a word choice which I think leads to a lot of unnecessary confusion regarding what is already a difficult topic! A more accurate word for what the universe is doing might be “stretching”.

    The difference between “expanding” and “stretching”, for me at least, is that an “expanding universe” conjures up an image where there is a bunch of galaxies floating through space, all of which started at some center point and are now moving away from that point at very fast speeds. Therefore, the collection of galaxies (which we call the “universe”) is expanding, and it is certainly fair to ask what it is expanding into.

    The current theories of the universe, however, tell us that this is not the picture we should have in mind at all. Instead, the galaxies are in some sense stationary – they do not move through space the way that a ball moves through the air. The galaxies simply sit there. However, as time goes on, the space between the galaxies “stretches”, sort of like what happens when you take a sheet of rubber and pull at it on both ends. Although the galaxies haven’t moved through space at all, they get farther away from each other as time goes on because the space in between them has been stretched.

    Comment by mcgonnigle — January 30, 2013 @ 12:16 pm | Reply

  4. A friend here at work suggested you go to the Nova website and post your question and some geekster will answer it.
    GB

    Comment by Greg Birrer — January 30, 2013 @ 12:59 pm | Reply


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