I believed to the dark matter thing before, but after I know how the human vision pathway work, I thing it is a misunderstand.
On my opinion, the universe dark because it was huge. All photon that travel to the edge looses its power to vibrating and stopped, that is why everything is dark. As we can see, our eyes had a spectrum on a thresholded range of the vibration. I dont know how can the sun lights hurt our eyes if we directly see it, but if it is painfull, it mean our eyes is damaged. X ray is something that we cant see, but how we can see the sun light but we cant see a light above x-ray? Sun light got to be more powerfull than the visible light power.
There is no dark matter. It was just our universe is huge. Huge enough to make the light loose its power when it travels.
No Farabi, I think you are wrong, there is such a thing as dark matter, and the older I get the more of it I acquire. :bg
:lol :lol :lol Sr Bil lCravener :U
The dark make us blind, and much light make us blind too.
A photon of light will continue to travel forever, without losing energy, unless it is stopped by something else.
The reason beams of light appear to get dimmer as they travel is due to dispersion (they spread out) so there are less photons to see in a given area.
Lasers spread considerably less, so they can go much farther before dimming, and that's what makes them appear 'strong.'
The universe is dark because it's so large, and there is so much 'empty' space, that there are stars soooooo far away their light hasn't yet reached Earth even though it's been traveling for billions of years.
The clues for dark matter are related to gravity, not light. It's named dark because we can't detect anything (including light) coming from it; but we can see the gravitational effects it has on other things that we can detect.
We can see sunlight because our eyes are tuned to detect those frequencies. We don't see x-rays because they serve little purpose to us (and they're quite damaging to cells.) The Sun also gives out x-rays, ultra-violet, infra-red, and numerous other frequencies - it has little to do with power (x-rays are actually more powerful than visible light) and more to do with frequency.
Tedd's onto it :P
what physicists describe as "dark matter" or "dark energy" are possibly the effects of the unseen black holes that exist in the universe
i tend to think of black holes as "junk yards" of the universe - lol
they collect shit and, generally, keep it from the public eye
can't get any more technical than that on my first cup of coffee :bg
Hi,
Black holes are a small part of dark matter, if a part of it
at all. Most, if not all, black holes are accreting matter and
spitting some back out in very bright jets. And have nothing
to do with dark energy.
Observation of the movement of stars within galaxies, the
retention of hot gas in galaxy clusters, movement of galaxies
in galaxy clusters, and gravitational lensing show that matter
that we see only accounts for ~27% of all matter that produces
gravity. The movement of the universe implies a dark energy
that is modifying the overall size of the universe. Adding
that in and visible matter is less than 10% of the "stuff" that
is "in" the universe.
Candidates for dark matter include Weakly Interacting Massive
Particles (WIMPs), Massive Compact Halo Objects (MACHOs),
axions, neutrinos, and other stuff. Some MACHOs could be
naked black holes.
The dark nighttime sky is known as Olbers' Paradox. Edgar
Allan Poe wrote an essay on that problem. Basically the sky is
dark because there hasn't been enough time to have light
coming from all points in the sky. The universe expanding
implies there never will be enough time.
Regards,
Steve N.
Hi,
Something to slow you down, mostly pretty pictures.
Cheers,
Steve N
Cluster Crash Illuminates Dark Matter Conundrum (http://apod.nasa.gov/apod/ap070820.html)
Dark Matter Ring Modeled around Galaxy Cluster CL0024+17 (http://apod.nasa.gov/apod/ap070516.html)
Dark Matter Map (http://apod.nasa.gov/apod/ap030814.html)
Dark Matter, X-rays, and NGC 720 (http://apod.nasa.gov/apod/ap021026.html)
Distant Supernova, Dark Energy (http://apod.nasa.gov/apod/ap010404.html)
Dark Energy, Dark Matter (http://science.nasa.gov/astrophysics/focus-areas/what-is-dark-energy/).
great info, Steve :U
but, i think you forgot one...
Dark Vader (http://en.wikipedia.org/wiki/Darth_Vader)
:bg
I just love a good mystery,...
Especially, one that makes absolutely no sense at all,...
i like this one
it serves to remind us that we don't know everything there is to know about the world we live in
DAVE !!!
That seems to be your favorite theme,...
I myself don't believe that Dark Matter is a reality. I think we just don't understand gravity at the cosmogenic level,...
truthfully, we don't understand gravity on any level - lol
my favorite physics "problem"
Newton helped a lot by deriving some formulas to describe it's behaviour
however, they do not explain the true nature of it's existance
very much a piece of the "unified theory" puzzle
The funny part is that there is no evidence for dark matter or dark energy at all, both have been postulated to account for observable phenomenon in the universe. We know from spectral shift that the universe is expanding and at an an accelerating rate but even that assumes the reaches of the universe over billions of years behave in the same manner as close observable phenomenon.
As a rough description the "Big Bang" theory more of less fits the observable data but it hardly gives you a working chronology of any great reliability. The problem is there is no easily constructed method of verification of cosmological theory as the universe in the form we understand it is beyond a scale that we can travel around.
HUTCH,
You stated it perfectly. If you examine Newtonian solutions for the orbital configuration of just our local Solar System,...and, if you then try to extend these statistics dynamically either forward or back in time,...the solutions diverges into chaos within a period of a few hundred thousand years.
that's right
we don't know what's going on beyond the "walls" of our universe
i.e., the big bang was an event that occured something like 14.8 billion years ago
we cannot see beyond that - and even if we could, we don't have great technology for seeing things
I think most cosmologists think the Big Bang theory is inadequate too, but, it explains alot.
Frankly, I think we have just identified the point where all the unknowns converge with an arbitrary timeline.
The event (the Singularity), is absurd, though,...in that it seems to violate all the known laws of physics.
We have no reason to believe that all the matter in the known Universe could be compressed into the state the precedes the Big Bang.
...Except that the mathematics indicate the possibility is inevitable,...
Of course,...you've got to keep in mind the well-known fact that: I'M WRONG ABOUT ALMOST EVERYTHING !!!
some answers, we may never have - and this may be one of those
i am good with that :P
thing is - maybe the gravitational effects of mass from adjacent universes is tugging on our pant-legs :U
DAVE !!!
Why do I get the distinct impression that you've been there and back ???
lol
Greatful Dead comes to mind....
"what a long, strange trip it's been" :boohoo:
(and the weed was excellent!!!) :bdg
O I C so it was reffereing to a graviti not a universe. I guess I make mista then.
Talking about the universe, I always sure that it was start from a gas. And then a particle suddenly move fast, really fast, so if it hit our eyes, our brain will interpret is as a light, about afew 400 Thz the physic says, and then it is hiting each others, so there are bright light on the universe. And then, the proton and neutron I dont know how is formed and the electron make an orbit on it. Look at the moon, it was at least a carbon, it was very hard, so do maybe, mars, except jupiter, it still a gas they said. But the strange thing is the earth. It had a lot of waters, an hidrogen and a oxygen, which only had one and two electron/s orbit on it. Weird eh?
Quote from: dedndave on August 23, 2011, 11:46:00 PM
truthfully, we don't understand gravity on any level - lol
my favorite physics "problem"
Newton helped a lot by deriving some formulas to describe [its] behaviour
however, they do not explain the true nature of [its] existance
very much a piece of the "unified theory" puzzle
Hi,
Sorry for the edits, incorrect apostrophes bug me.
In one sense the General Therory of Relativity explains the
existence of gravity. Mass causes a distortion in space-time.
Of course then we (you?, I?) have to explain mass, and off
to the Higgs particle/field postulates. Fun?
Cheers,
Steve
i put those apostrifies in there just for you, Steve :bg
i hold that the terms "mass" and "gravity" are the same thing
we use different words because our tiny little minds need to put things in context
...a fact that illustrates our lack of understanding of a concept
to take it one step further, "matter"/"mass"/"gravity" may be viewed as a state of energy
much like we view solid, liquid, or gas as states of matter
Hi Dave,
Quote from: dedndave on August 24, 2011, 03:12:47 PM
i put those apostrifies in there just for you, Steve
You're too good. <g>
Quote
i hold that the terms "mass" and "gravity" are the same thing
Um, no. Mass implies more than gravity. Inertia. Filling of
space. Physical characteristics, except for some variations of
dark matter, such as color and texture. Gravity tends to imply
mass. Whereas mass may not imply significant gravity. Nit.
(Ducks.)
Quote
to take it one step further, "matter"/"mass"/"gravity" may be viewed as a state of energy
much like we view solid, liquid, or gas as states of matter
Reminds one of the Special Therory of Relativity. One wonders
how the established physicists felt about things before and after
1905. An invariant speed of light and matter and energy being
linked must have been somewhat resented. Energy and matter
don't look much alike to a lay person. The speed of light being
the same regardless of the movement of the viewer seems to
be counter intuitive to a naive logic.
Oh well,
Steve N.
QuoteWhereas mass may not imply significant gravity.
not too sure about that one :bg
we define mass by the effect or "pull" it has on another body
...sounds like gravity, to me
I've been reading up on Gravity (http://en.wikipedia.org/wiki/Newton's_law_of_universal_gravitation), so that when I make nebulous statements, I won't sound like a complete idiot.
If you review the history of the theoretical development of Newton's version of gravity, you will notice that he developed the mathematical basis of the theory to fit observations of planetary orbital configurations known at the time (1686). This was such a major breakthrough, that it dominated all thought until Einstein published his Theory of General Relativity (http://physics.about.com/od/relativisticmechanics/a/relativity_4.htm) in 1905. "In 1915, Einstein published a set of differential equations known as the Einstein field equations. Einstein's general relativity depicted the universe as a geometric system of three spatial and one time dimensions."
"When physicists attempt to apply quantum field theory to the gravitational field, things get very messy. In mathematical terms, the physical quantities involve diverge, or result in infinity. Gravitational fields under general relativity require an infinite number of correction, or "renormalization," constants to adapt them into solvable equations. "
My current crackpot theory,...is that, we've been seduced by the mathematics (because it explains our current understanding accurately).
And,...I enthusiastically subscribe to the Dave Phenomena (lots of stuff we don't know): Calculus will prove to be inadequate in describing Gravity in all it's glory.
Intergalactic space travelers know this. Which explains why Interstellar spaceships don't actually travel at relativistic speeds.
...Otherwise,...there would be thousands of them parked out around Saturn,...
dark matter and dark energy,next theory they will come up to probably will talk of dark force and SithLords :bdg
who could have known, George Lucas was so close to the truth?
Quote from: dedndave on August 24, 2011, 04:35:30 PM
QuoteWhereas mass may not imply significant gravity.
not too sure about that one :bg
we define mass by the effect or "pull" it has on another body
...sounds like gravity, to me
That "pull" is inversely proportional to the square of the distance between the bodies.
Inertia depends only on the mass of a body, so I see it as the defining property of mass.
What we really need is a MASM Forum community Project to: Redefine Post-Newtonian Gravity, and, maybe even, Minkowski Spacetime.
It'll take light-years,...
Required reading: Experimental Tests of General Relativity (http://arxiv.org/PS_cache/arxiv/pdf/0806/0806.1731v2.pdf)
...And, this will probably inspire a rapprochement with our extraterrestrial neighbors, who undoubtedly think we're all a bunch of infidels,...
Hi,
Nice point Michael. Anyway I put the word significant in for a
reason. Two examples for your consideration.
One is the electrons in a wire. You should agree that electrons
have mass. But when was the last time you needed to calculate
the gravitation they create? I tend to ignore that effect.
Another from the world of science fiction and calculus. You are
an advanced race and you create a hollow world (a spherical shell).
Integrate the gravitational effects of the matter in the shell of that
world. If you are on the outside there is a gravitational field pulling
you towards the center of mass. Rather normal. But if you are
on the inside, should you be pulled to the center of mass? Or
should you be pulled towards the shell so you could walk around
on it? It, of course, turns out to be neither. You would be
weightless. So while you are being affected by the gravitational
field, it is uniform, and the effect is nil. I seem to remember
not getting the right result when I first tried solving it.
baltoro, the simpler Special Theory of Relativity was in 1905.
Speed of light, observations depending on the viewr's frame of
reference, increased mass and slowing of time as you approach
the speed of light, and E = MC**2 kind of things. The General
Theory of Relativity first came out in 1916. It is a more complex
theory... Gravitation, frame dragging, gravity affecting light, and
gravity slowing time kind of things.
Infidels? You think?
Anyway, I think that dead horse has been flogged enough.
Cheers,
Steve N.
Edit: deleted iffy item.
SRN
as for the electrons "flowing" in a wire
when i was in college - lol - 30 years ago....
they weren't sure if the electrons actually traveled from one atom to the next, or just the field of charge
i suppose that has been answered, by now
but - if the mass moves, it is replaced by the mass of the electron that replaces it
otherwise, we might see wires jump when you flip a switch :bg
it takes a complete circuit for current to flow
STEVE (aka, FORTRANS),
You clearly know what you are talking about,...(my understanding of the subject is nebulous at best),...
Here are a couple of papers which you (and other General Relativity fans) might find informative:
Is General Relativity 'Essentially Understood' ?, 2008 (http://arxiv.org/PS_cache/gr-qc/pdf/0508/0508016v1.pdf)
What Was Einstein's Principle of Equivalence ? (http://www.pitt.edu/~jdnorton/papers/ProfE_re-set.pdf)
Einstein's Bumpy Road to General Relativity, 2005 (http://www.nd.edu/~kbrading/Classes/Phil%2093871/Of%20Pots%20and%20Holes.pdf)
...And, if you have an IQ higher than Spock's,...and, are thinking seriously about space travel,...you'll love this overview:
Relativistic Reference Frames for Astrometry and Navigation in the Solar System, 2006 (http://arxiv.org/PS_cache/astro-ph/pdf/0610/0610022v2.pdf)
Hi,
A static charge would change the number of electrons. How
much does a lightning bolt weigh? I guess a better example
would be the electron beam in a CRT. Does anyone worry
about the gravitational field of that?
Flowing electrons. How could you move the field without
moving the electrons? Anyway, I read an article a while back
where they were showing how some electromagnetic property
was caused by relativistic effects of the electrons velocity.
The electrons in one wire were "seeing" the ones in another
wire getting closer together due to relativistic foreshortening.
So they apparently thought the electrons were moving.
Cheers,
Steve N.
QuoteA static charge would change the number of electrons.
How much does a lightning bolt weigh?
they must be very heavy - they always come down :U
QuoteI guess a better example would be the electron beam in a CRT.
Does anyone worry about the gravitational field of that?
i can tell you from personal experience that the electrical field is what you have to worry about
it will set you on your ass :lol
http://www.physicsclassroom.com/class/circuits/u9l2c.cfm
Hi,
Thanks for the suggested links baltoro. Too bad my attention
span and difficulty in reading from a monitor only allowed for a
few pages of each of the first three. Heady stuff,
Regards,
Steve
:bg
there is an alternative to DARK MATTER, its GREY MATTER (GRAY MATTER for our friends in the US) but sad to say we don't see much of it these days. :P
Steve,
That was what I tried to imply in my first post to Farabi, that is to say, the older I become the more dark matter (dead brain cells) I acquirer. I think my comment passed over most heads though. :bg
Hi Bill,
It was subtle, but not overly so. (IMO)
Cheers,
Steve N.
all planets you cannot see, doesnt those count as dark matter and all life on planets is using energy to live but not enough to be seen from other stars, doesnt that count as dark energy?
If E=MC^2 is anything to go by...
E= energy.... you cannot see most of it, It has mass and wavelength.
Anything with a wavelength has mass and energy..etc..
It's a simple observation that is right in front of our noses. There's your 'dark' matter
An extension to mass is that it 'has' gravity, therefore gravity is also dark matter, energy and wavelength... and visa versa.
Maybe I should stop before I make the world's top theoretical physisists look like 'turkeys'... :bg
i'm not sure we can say that "energy has mass"
i think that's like jamming a square peg into a round hole
as i mentioned earlier, "matter is a state of energy"
so i suppose, when it's in that state, it does have mass
i guess i need to try and define the other states of energy
potential, kenetic - damn - i have have a puzzle with all square pieces and all round holes :bg
Quote
'm not sure we can say that "energy has mass"
Yeah, it doesnot even a catholic :lol
(http://l.yimg.com/us.yimg.com/i/mesg/emoticons7/24.gif)
that's a pretty good one, Farabi :bg
Hi,
Interesting pictures.
Enjoy,
Steve N.
Hubble Captures Time-Lapse Videos Of Stars Being Born
(http://www.npr.org/blogs/pictureshow/2011/08/31/140087297/hubble-captures-time-lapse-videos-of-stars-being-born)