"There are stars leaving the Milky Way, and immense gas clouds falling into it. There are turbulent plasmas writhing with X- and gamma-rays and mighty stellar explosions. There are, perhaps, places which are outside our universe. The universe is vast and awesome, and for the first time we are becoming a part of it." -Carl Sagan
It’s no secret that if we look at the matter we see in the Universe, the story doesn’t add up. On all scales, from individual galaxies to pairs, groups and clusters of galaxies, all the way up to the large-scale structure of the Universe, the matter we see is insufficient to explain the structures we get. There has to be more matter, both normal (atom-based) matter and dark (non-interacting) matter, to make our theory and predictions match.
In a wonderful new pair of papers, two independent teams have detected the warm-hot intergalactic medium along the large-scale structure filaments in the Universe. With six times the normal matter density, this accounts for a significant fraction of the missing normal matter in the Universe! It’s estimated that 50-90% of the baryons in the Universe are part of the WHIM, and this could be the first step towards detecting them. But it doesn’t touch or change the dark matter at all; we still need it and still don’t have it.
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"Neutral atoms formed when the Universe was a mere 380,000 years old; after hundreds of millions of years, the hot, ultraviolet light from those early stars hits those intergalactic atoms. When it does, those photons get absorbed, kicking the electrons out of their atoms entirely, and creating an intergalactic plasma: the warm-hot intergalactic medium (WHIM)."
So the UV light from earliest stars keeping the intergalactic gas hot (and does it perfectly for all gas atoms somehow).
But how it is possible that UV light photons stayed same after billions of years of expansion of universe?
I have a really crazy idea on this WHIM which maybe a better explanation though:
What if WHIM is no ordinary gas?
What if WHIM is an effect similar to Hawking Radiation?
What if spacetime is created by virtual particles as an emergent property?
What if Gravitational Fields are polarization of spacetime?
(Where positive curvature indicates probabilities of positive energy/mass virtual particles are higher in that region and negative curvature indicates probabilities of negative energy/mass virtual particles are higher in that region.)
In case of WHIM, imagine Dark Matter particles increase probabilities of positive energy/mass virtual particles and we observe it as hot gas.
Imagine any (+/-) unbalanced probabilities for virtual particles, on the path of light rays, act like different gas mediums that change the local refractive index, so the light rays bend.
And in case of BHs, imagine probabilities of positive energy/mass virtual particles increase so much nearby, some of those particles turn real, that we could observe as Hawking Radiation.
missing mass problem for Dark Matter, or Dark Energy. I suggest both arise from a (Sub-)Quantum Effect, a prediction from a theory more general than Quantum Physics as we know it today. The basic idea is that there is something one should know as the “Quantum Interaction”, and it proceeds at a finite speed.
The “Quantum Interaction” would be the Entanglement speed and the Collapse speed. Over cosmological distances, it leaves remnants: Dark Matter. It also weakens gravitation over cosmic distances, accelerating the universe.
Some will scoff. However, basic ideas in physics can be simple.
I just realized if my ideas about true nature of spacetime and gravitational fields (stated above) are correct then it would mean Casimir Force actually can be thought as creating artificial gravity, like in Star Trek for example. :-)
A generic comment on "what if" 'science':
What if pigs could fly? It would be one of infinitely "possible" "universes.' (Excuse my excessive quotes. It's all imaginary except that the Universe is "one verse.")
Ducking pig shit or having a good umbrella would be ordinary reality in that "universe."
But scientifically speaking.... just kidding.
I am guessing if positive spacetime curvature slows down time then negative should speed it up. Then if Casimir Force is creating spacetime curvature, and since we can make it negative in the lab, then we can make time move faster, and it maybe measurable in the lab.
"Missing Matter Found, But Doesn’t Dent Dark Matter"
Translation into scientific realism:
We found more normal matter but we still have no idea what else we can not yet detect which might generate gravitational force to explain our astronomical observations.
Might be that it's normal (baryonic) matter that our excellent equipment is still not able to detect. (Instrumentalists would hate to admit that.)
@Michael Mooney #10,
I was thinking along similar lines. If the stats were off before, and every time they improve instrumentation they discover more things, (in the early 20th century they thought the size of the universe pretty much was our galaxy) what compels some to keep making definitive statements of certainty and creating models based on such very limited information? I'd think some would start saying, 'save your breath until the fat lady sings.' While I can understand people want to understand the proportional make up of the universe, I keep asking "how do you know how much of it you are looking at to base your proportions on?" Unless you know big something is, saying 50%, 20% etc, is meaningless. Until that is known, all guesses, and they are just guesses, should be tempered with prudence. I would suggest blatantly keeping all estimations always within only what has been measured, and be very clear about what that encompasses at the time the calculation is made. This would then start to provide a precise time lapse record of how much scientific estimations change with new data.
I wonder if we could use sheets of Graphene like Casimir Plates and stack them as countless layers to create a multiplied Casimir Force generator. Then we could also add a strong electric and/or magnetic field to amplify that force.
Would a device like that could create human weight level strong artificial gravity field?
And of course "What if pigs could fly?"
Thanks for reminding us this big question MM.
I don't think I know the right answer.
I think you always bring joy to this website and keep it alive.
I apologize if I ever hurt your feelings.
I always indicate when I am just kidding.
Pretend you get what you want, I call this the god game. Give yourself whatever you want, but afterwards roll with the punches of consequences that follow. If you could produce a machine that generated gravity in a small localized area, what else do you think might happen?
If the gravity was generated at small location, everything would be drawn to this small location, not very suitable for walking around, unless your ship was built like an onion, layers within layers. If the field could somehow be put into the flooring, this would created a problem too, as unless the field was very small, people on the deck below would be pulled upwards into their 'ceiling'. If you put the same effect on each deck, you would be pulled upwards and downwards at the same time....this doesn't sound very practical for normal human movement either. Also, gravity has the effect of pulling something down towards the source, but would this not cause all kinds of stresses on your space ship structure as well? You might be much better off just using centrifugal force in large spinning sections, and magnet shoes in areas where that wasn't practical, it might save an awful lot of engineering headaches.
Imagine you made bricks of artificial gravity generators.
Imagine a spaceship (or spacestation) with a single floor of those bricks. Imagine the crew walks on top and bottom of that single floor (upside-down to each other). So you have a kind of symmetric (up-down) 2 floor internal spaceship design.
Also what if those brick can also create artificial anti-gravity?
(Wikipedia says we can generate both attracting or repelling Casimir Force.)
If that is possible, imagine each floor of spaceship is 2 layer of bricks. Top layer generates gravity, bottom layer generates anti-gravity. People on top feels downward force of gravity but people on the lower floor does not feel upward force of gravity, because the anti-gravity layer (which they are closest) cancels out total gravity to zero for them.
I wonder what would happen if we somehow created artificial gravity in front of a spaceship and artificial anti gravity in the back? Could that cause the spaceship to move forward faster and faster, like keep falling in a gravity well?
Interesting concept, but I'm not sure you even can have something that is only gravitational on one side (I know of no examples in reality), that sounds more like electro magnetism than gravity.
At the risk of bursting your balloon, trying to make spaceships and stations like horizontal office buildings may just not be in the cards of possibility.
If we can create artificial anti-gravity, I think it could be also useful as a shield in space, against space dust etc.
There is evidence of the strongly interacting dark matter every time a double slit experiment is performed, as it is what waves.
Again, MM and CFT, you show your lack of understanding. The "missing matter" discussed in this post is normal matter. We know from real, actual observations of how things gravitate that we were not seeing all of the normal matter that exists. This WHIM is at least some of that missing normal matter.
We know also, again from real observations, that either one of two things must be true. Either there is matter out there that is not normal, baryonic matter, but rather must have certain properties and interactions -- this is known as dark matter. The alternative is that our models of gravity are wrong, i.e. we need to come up with a modified version of the laws of gravity -- this is known in the physics community as Modified Newtonian Dynamics, or MOND.
How do we determine which alternative is correct? Contrary to what you guys seem to think, it is NOT just assumed that our current theory of gravity is correct and that there must be dark matter. The various flavors of MOND have indeed been given careful consideration. In general, these were designed to account for galactic rotational anomalies, and it's unsurprising that they do better than dark matter at explain galactic rotational speeds. However, these MOND models are atrocious at all other scales, whereas dark matter does very well at all other scales.
Does this mean that dark matter is right and MOND is wrong? Maybe, but not necessarily. If you still think MOND is the answer, then it's incumbent on you to come up with a new version of MOND that accounts for observations on ALL scales better than dark matter can. If you (or anyone else) can do so, then MOND will supplant dark matter and we will reject the idea of dark matter. If not, then dark matter is the best idea currently available, and it is the model that most physicists will continue to investigate further.
Dark matter fills 'empty' space and is displaced by ordinary matter. What are mistaken for dark matter filaments is actually the state of displacement of the dark matter.
Galaxy clusters move through and displace the strongly interacting dark matter, analogous to a caravan of submarines moving through and displacing the water.
@ Frank re: cassimir effect vs gravity
Cassimir effect is not similar to gravity. There is no "attraction" between the plates. Instead (as understood) it is vacuum energy pushing the plates because the number of modes outside is greater then the number of modes between the plates. No matter how large of cassimir apparatus you build, it still doesn't effect anything outside of plates themselves. Thus, bricks based on anything relating to cassimir effect would just contract themselves and nothing significant would happen.
For gravity. you need mass or energy. Super large amounts. In principle, if you could build a mega dynamo machine, that generates massive amounts of energy, that would cause it to bend spacetime and thus act as gravitational source to things nearby. Anti-gravity is a completely different beast, I don't know how that would work... even in theory. A dark-energy powered machine maybe.
What if Planck particle is the smallest and Dark Matter particle is the biggest size/energy particle of the Universe?
More on Ethan's "un-dented" dark matter, from Axil's link on the "kill list" post.
From the New Scientist, Leah crane, Oct, '17:
"Two separate teams found the missing matter – made of particles called baryons rather than dark matter – linking galaxies together through filaments of hot, diffuse gas."
New Scientist, Sabine Hossenfelder and Naomi Lubic, '15:
"Strangely familiar: Is dark matter normal stuff in disguise?...
***Dreaming up new particles to explain the universe’s missing mass has got us nowhere.*** Great clumps of quarks stuck together in weird ways could do the trick." (My *** emphasis.)
@ cft #11 the same thought has occurred to me. i believe we are only seeing .000001% of the actual whole multi universe universe
(Still here for now.)
" Unless you know (how) big something is, saying 50%, 20% etc, is meaningless."
This point has always been obvious to me too. I wonder how such a simple, basic truth keeps eluding instrumentalist mathematicians like Ethan.... The pretense of knowing more than is known... and the math to "prove it."
Same with the possibility of a perpetually oscillating, "bang/crunch" universe. If the time scale of such a two phase cycle is beyond our ability to measure, the cosmology is discarded. (Hey, it's still expanding at an accelerating rate!... so that one is impossible, they say.)