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The Search for Dark Matter and Dark Energy
mlimber writes "The New York Times Magazine has a lengthy article on dark matter and dark energy, discussing the past, present, and future. 'Astronomers now realize that dark matter probably involves matter that is nonbaryonic ["meaning that it doesn't consist of the protons and neutrons of 'normal' matter"]. And whatever it is that dark energy involves, we know it's not 'normal,' either. In that case, maybe this next round of evidence will have to be not only beyond anything we know but also beyond anything we know how to know.'"
..."in-transit" energy from 100,000,000,000 stars?
...large amounts of completely non-reflective dust and asteroids?
...a side effect of over-estimating the size of the universe? (i.e. stars like our 5 billions light years away don't exist anymore)
/real questions
//just curious..
+&x
Very large bodies don't behave according to Newton. Very small bodies behave according to the rules of quantum physics, so it's clear that one law doesn't regulate every case. Dark matter/energy are just a fudge factor because we can't explain what happens without them, but that doesn't prove that they exist. All that is proven is that we don't understand what is happening.
Please move along.
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"Since the invention of the telescope four centuries ago"
I didn't know telecopes were that old. Is this a typo, and didn't they mean decades instead? If not, what did ancient telescopes do?
FooBarWidget, meet Galileo: Widely credited as the inventor of the modern telescope, in 1609.
Though, as with all major developments in human history, some accounts have him as merely improving on preexisting tech, whether copying the work of Lippershey from 40 years before, or even the possibly MUCH older designs of the ancient Persians.
So no, not a typo.
At this point, dark energy is really nothing more than a fudge factor. It's certainly nothing like the normal concept of energy. We don't even know if it's a cosmological constant or if it varies over time and space, let alone whether it's a property of spacetime or some form of particle. So far, I'm still unconvinced that it actually exists: it seems more likely to me that the current theories are simply slightly off in their formulas, and can be resolved without recourse to another of Occam's entities.
ceci n'est pas une
On the contrary, very large bodies are extremely well-approximated by Newton, as it is the slow-velocity, weak field limit of General Relativity. There is already good photographic evidence for dark matter in the form of colliding galaxies (do your Google work), and current observational evidence points pretty strongly towards dark energy in the form of a cosmological constant. While it's true we don't know what that means, it's not just a fudge factor.
To follow knowledge like a sinking star, / Beyond the utmost bound of human thought. ("Ulysses", Tennyson)
That's an educated opinion, if I've ever heard one.
Karma police, arrest this man. He talks in math. He buzzes like a fridge. He's like a detuned radio.
If dark matter makes up most of the mass in the universe, wouldn't the kind of matter we're familiar with be the abnormal kind?
Ceci n'est pas une signature.
These are things that can be and are published in scientific journals. Whereas the only real observable evidence for the phenomena you mentioned are documentaries :/
To follow knowledge like a sinking star, / Beyond the utmost bound of human thought. ("Ulysses", Tennyson)
The difference is that there are NOT many different studies confirming ESP happens. In fact, there are many studies arguing the contrary (particularly if you focus on studies from reputable sources). There are plenty of people who WANT ESP to be true, but I don't think there are many who have been convinced by the evidence.
One big take home point about dark matter and dark energy is that physicists didn't want them to be true! It took an enormous amount of evidence, with countless independent confirmations over decades to convince the community that they were real. Real evidence can do that - convince reasonable people who begin as non-believers.
This could all be accounted for by dark matter save for the observations of Type 1A supernovae which indicate accelerating expansion, and this requires domination by a state of matter with negative pressure, and this is what's been coined dark energy.
To follow knowledge like a sinking star, / Beyond the utmost bound of human thought. ("Ulysses", Tennyson)
I believe the children are the future.
I bet this one could have a nice career in the ministry of truth.
http://en.wikipedia.org/wiki/Black_hole#Black_hol
If it doesn't interact by the electromagnetic force, it cannot affect anything chemically. If it doesn't interact by the strong force, it cannot cause nuclear reactions. Even if it interacts by the weak force, the effect would be equivalent to the neutrinos already coursing through us. To my understanding, it's an explanation for effects specifically by gravity, which we already are experiencing.
Heh. Well, then, just send them to the Randi foundation which still has a 1 million dollar prize for anyone who can prove anything like that. The requirements so far have been reasonable too, usually along the lines of having a scientific double-blind test. Nothing you wouldn't expect in normal science. Altering probabilities is even more straightforward, since then you just have to take a large enough sample and do some elementary statistics. So you'd think that if ESP or mind-over-matter or whatever floats your fantasy boat was that proven and working, someone would claim the prize already. But, nah, suspiciously so far what we've had were:
- bullshitters arguing about how unsound scientific testing is, and why they won't take part in it (sorry, if something is only perceived when the test subjects are told and persuaded what they should perceive, then it's probably just make-belief.)
- lame stage magician tricks
- various versions of some global conspiracy to suppress them (funny how noone suppressed them before, then. You'd think the conspiracy would then stop them from publishing books and making faked movies about it too, not just stop them from taking part in a controlled experiment.)
Etc.
Plus, Randi isn't the only one who came up empty so far. What fraudsters are quick to tell you, as if it were some proof of ESP existing, is that both the USA and the USSR were interested in it during the cold war. That much is true. Unsurprisingly, since for example transmitting a message to a submarine by a mean that's (A) not blocked by water or rock, hence receivable from any depth or hole, and (B) impossible to intercept, is any army's or navy's wet dream. What they conveniently ommit there is that both the USA and the USSR, and a few others for that matter, failed to get any results with it.
By contrast, the people with these physics hypotheses tend to actually have some verifiable/falsifiable data, and they give it to you up front. If they did just bullshitting and handwaving like the ESP gang, we wouldn't take them seriously either.
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Here is an excellent article by Sean Carroll of the California institute of Technology that explains why all the suggestions of the parent post may not be correct.
Basically, what it says is that if two large clusters of galaxies went right through each other, and dark matter was really like the normal matter in the way the parent post suggests, we would get a different result from what would happen if dark matter was for real. Astronomers have discovered one such system and this provides conclusive evidence for the existence of dark matter.
Mistakes happen in all fields, to say that one particular example (or, indeed, given the human capacity to screw up, numerous ones) renders a field meaningless is highly dubious. What is significant is that significant results are rechecked and errors are given the chance to be corrected - something which this story demonstrates.
GR does not work at Galactic Levels, so there is no question of it working at the Cosmic levels.
r g%3Aastro-ph%2F0610298 (A New Force in the Dark Sector?)r g%3Aastro-ph%2F0609125 (Fits the Bullet Cluster with TeVeS, the MOND relativistic theory)
The real problem is MOND. If it did not exist then Dark Matter would be free to exist wherever it wanted. But with MOND the picture becomes more complex, now DM must fit MOND. It is quite easily provable that DM cannot fit MOND, just apply it to small cluster of stars at the outer edge of Milky Way which show Dark Matter. The problem is that for DM to fit Milky Way, it cannot be present in the Clusters. But some clusters do require DM. Now MOND fits both reasonably.
If you talk about Bullet Cluster, then don't because it proves that DM should have a new type of interaction because the DM itself is experiencing higher gravity than relativity predicts. Now this can be due to MOND. MOND can be fit to the Cluster by using hot and massive neutrinos. See the following papers.
http://www.citebase.org/abstract?id=oai%3AarXiv.o
http://www.citebase.org/abstract?id=oai%3AarXiv.o
The additional benefit is that MOND supplies the higher than gravity force required to fit the velocity of DM in Bullet Cluster.
And what you think the public is going to know about it? Nothing. All they ever do is believe something's good or bad. They wouldn't even know about any blackholey thingies if it wasn't for science.
Now as scifi authors have popularized black holes, it's suddenly common knowledge that "black hole bad, do not want".
In some evil twisted way I sometimes hope for some experiment end in spectacular and anomalous failure so that all you roadblocks for scientific progress could be right for the first and last time. Just have enough time to yell: "we told you so!" That'd be sweet while it lasted. After which it would just suck. :(
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