It's software this time!

[Grench]

@Grench: neutrons are made out of charged particles. they just add up to zero electric charge. two down quarks (-1/3 charge each) and one up quark (+2/3 charge).

so there is a non-zero probability that light interacts with neutrons. i don't have a good source for this, but here's a related article. thus neutrons aren't dark matter...

Agreed that neutrons are not, "Dark Matter". However, they are 'normal matter' that is -very- hard to detect at low densities at great distances. If they were standing still, enough neutrons to make up the "missing mass/energy" of the universe, they would only need to have a density of 2.5 neutrons per cubic meter of the universe. 2.5 neutrons per cubic meter is the -maximum- density to fulfill the "missing mass/energy". They are likely not standing still, but would likely be whipping around at velocities ranging up to near the speed of light. The faster the average neutron velocity (energy), the fewer actual neutrons are required for this possible solution.

We have no ability to directly detect "Dark Matter".
We have no ability to directly detect 1.5 - 2.5 neutrons per cubic meter densities of neutrons in the intergalactic medium either.

Issue: "There is a whole lot of mass/energy in the universe that we cannot detect."

Assuming that there is a magic fairy dust and magical energies coursing about, "Dark Matter / Dark Energy" instead of assuming that maybe our measurement capabilities for normal matter might not be adequate (yet) to get a full tally of normal matter / normal energy seems a bit of a stretch.

I am not saying, "This is the way it is." I am proposing an alternate solution model, hypothesis, that fulfills the scenario presented. We do not, to my knowledge, have any current technological means to test either the, "Dark Mater / Dark Energy" hypothesis or my "Presence of Neutrons at Low Densities in Intergalactic Space" hypothesis.

 

[Bosbeetle]

the intergalactic medium

Computer says no.

 

[λ the β-Redex Reducer]

And to your first question instead of beleive I would use the word "know" or maybe "acknoledge" or "accept". Just a bit less fuzzy and religious than beleive.

Dictionaries seem to be pretty clear about it: "To accept as true or real." "To credit with veracity." "To expect or suppose; think."
"know" is wrong because that only refers to true beliefs, "acknowledge" can mean having heard something without believing it, and "accept" can mean accepting something emotionally or physically. All those words are either wrong or ambiguous as well. IMO "believe" is a great word to express the concept of believing.

In Dutch the word for "belief" is often used synonymous with the word for "religion". Their meaning is separate but can overlap, not all beliefs are religious beliefs and not all religious ideas are believed in by their practitioners. It's just a case of sloppy language making language more ambiguous and less expressive. If this usage of the words gets popular then the Dutch language will lose the capability to quickly and unambiguously express the concept of believing in favour of having 2 words for the concept of religion.

 

[Bosbeetle]

To know is wrong because it refers to true beliefs? I think there you are making the distinction I want to apply. I know evolution exists. I would never say I beleive in evolution. The latter is quite nonsensical in my opinion. But it all might have to do with me being a non-native speaker. Saying I beleive in evolution would for me be the same as saying I beleive in cars.

 

[ible]

Agreed that neutrons are not, "Dark Matter". However, they are 'normal matter' that is -very- hard to detect at low densities at great distances. If they were standing still, enough neutrons to make up the "missing mass/energy" of the universe, they would only need to have a density of 2.5 neutrons per cubic meter of the universe. 2.5 neutrons per cubic meter is the -maximum- density to fulfill the "missing mass/energy". They are likely not standing still, but would likely be whipping around at velocities ranging up to near the speed of light. The faster the average neutron velocity (energy), the fewer actual neutrons are required for this possible solution.

We have no ability to directly detect "Dark Matter".
We have no ability to directly detect 1.5 - 2.5 neutrons per cubic meter densities of neutrons in the intergalactic medium either.

Issue: "There is a whole lot of mass/energy in the universe that we cannot detect."

Assuming that there is a magic fairy dust and magical energies coursing about, "Dark Matter / Dark Energy" instead of assuming that maybe our measurement capabilities for normal matter might not be adequate (yet) to get a full tally of normal matter / normal energy seems a bit of a stretch.

I am not saying, "This is the way it is." I am proposing an alternate solution model, hypothesis, that fulfills the scenario presented. We do not, to my knowledge, have any current technological means to test either the, "Dark Mater / Dark Energy" hypothesis or my "Presence of Neutrons at Low Densities in Intergalactic Space" hypothesis.

go ahead and get the latex ready, send out a preprint to the arxiv.

one possible flaw - dark matter is in our galaxy, too. super speed neutrons ripping through us near the speed of light would not be so good for us. https://en.m.wikipedia.org/wiki/Neutron_radiation

also that article mentions something i forgot -- free neutrons are unstable, they decay into protons and electrons. so that's another strike.

i think it's good to think about solutions that others may have missed, but i would avoid the tone that imagines their solutions are somehow inferior or not taking into account Occam's razor. we're all dealing with partial information now. the answer might look obvious in hindsight, but it's not obvious now.

 

[matzesu]

"Dark (Live) Matters"

I wonder if there would be such a Deep Physical Discussion on a Board for a diverent Gaming Handheld or an Iphone..

Could it be that i am not educated enough for the Pyra ?? Altough i also read the Comon Sience Magazines, , whe have this "PM" Magazin in Germany,
When i first got the Magazine Abonoment for Birthsday, lot of years ago, it was much more serious, but then they got Artikels like "Which Animal matches which House in Game of Thrones ^^

 

[λ the β-Redex Reducer]

I wonder if there would be such a Deep Physical Discussion on a Board for a diverent Gaming Handheld or an Iphone..

Probably, considering the fact that there are many different forums talking about iPhones. However, 100% of all Pyra forums talk about physics, the percentage of all iPhone forums that talk about physics may be lower.

Could it be that i am not educated enough for the Pyra ?? Altough i also read the Comon Sience Magazines, , whe have this "PM" Magazin in Germany,

No, the relevant fields are computer science and electronics. Theoretical physics is for boring nerds; computer science is for cool studs like me.

 

[daveshah]

No, the relevant fields are computer science and electronics. Theoretical physics is for boring nerds; computer science is for cool studs like me.

Don't forget the mechanical side too, a Pyra without a case would be a pretty useless device (but also the kind of thing that electronic/software types like me are liable to make...)

 

[levi]

It might also be a language thing beleving (at least if I use the dutch translation) is a bit to void of falsification and also seems to imply a not changing view of things. No need to check truthfullness if you beleive in it. Also I think beleiving in science as a method might be okay but beleiving in science as a whole is to much, like I said before when you're dealing with the bleeding edge of science it's very healthy to take things with a grain of salt and don't discard any hole in the theory you can think of. And discuss or think of ways to unmask or remove that hole. But I might be to much working inside of science to percieve an outsiders look on it.

Indeed. As Terry Prachett wrote 'I don't believe in chairs', because the way to conceive of and to use chairs is physically evident; whether you believe in them or not they're still there. It's a matter of language, and the boundary between 'I support the assertion that...' and 'I believe that...' and 'It is true that...' isn't always the clearest.

 

[Grench]

one possible flaw - dark matter is in our galaxy, too. super speed neutrons ripping through us near the speed of light would not be so good for us. https://en.m.wikipedia.org/wiki/Neutron_radiation

also that article mentions something i forgot -- free neutrons are unstable, they decay into protons and electrons. so that's another strike.

Our galaxy (and the rest in the Laniakea cluster) would be hoovering these neutrons up via gravity in it's path through the universe just the moons of Saturn clear paths through the rings. I was pretty specific when I based my hypothesis on these being free neutrons in intergalactic space. Densities in and near galaxies and galactic clusters would be -far- lower. But, the volume of galaxies and galactic clusters is rather minute compared to the volume between them.

You are right, though. I had not taken free neutron decay into account. The next, and probably better, fit to this would be highly diffuse hydrogen. Which has near enough the same mass as a neutron. Which would still be undetectable by today's means at a density of <= 2.5 atoms of Hydrogen per cubic meter of intergalactic space.

When disturbed by galaxies in motion, that disperse, cold Hydrogen would get excited and show up as:
https://en.wikipedia.org/wiki/Warm–hot_intergalactic_medium

 

[λ the β-Redex Reducer]

Indeed. As Terry Prachett wrote 'I don't believe in chairs', because the way to conceive of and to use chairs is physically evident; whether you believe in them or not they're still there. It's a matter of language, and the boundary between 'I support the assertion that...' and 'I believe that...' and 'It is true that...' isn't always the clearest.

That way of defining belief makes the epistemological notion of knowledge as justified true belief an oxymoron.

 

[levi]

Well yes. As soon as something becomes true (I'm not sure what you mean by 'justified' there, unless it's a common english idiom), you no longer have to believe in it. Very little stuff in science actually becomes true, rather than extremely highly probable, so it's rarely a problem in practice.

 

[ible]

The next, and probably better, fit to this would be highly diffuse hydrogen. Which has near enough the same mass as a neutron. Which would still be undetectable by today's means at a density of <= 2.5 atoms of Hydrogen per cubic meter of intergalactic space.

When disturbed by galaxies in motion, that disperse, cold Hydrogen would get excited and show up as:
https://en.wikipedia.org/wiki/Warm–hot_intergalactic_medium

scientists also know about interstellar hydrogen, so they've probably already ruled this out. here is some caltech consolidation of other research which says that HI (interstellar hydrogen) still wouldn't be enough to explain the curves.

 

[Grench]

scientists also know about interstellar hydrogen, so they've probably already ruled this out. here is some caltech consolidation of other research which says that HI (interstellar hydrogen) still wouldn't be enough to explain the curves.

I read it. It deals specifically with hydrogen within galaxies, not between them. The vast majority of hydrogen within the gravitational effects of the galaxies themselves - and their trail through the universe - would have been absorbed into star formation and excited by radiation and put in motion by gravity. Although the behavior of hydrogen within galaxies is interesting, because we can see it, it tells us nothing whatsoever about what does or does not exist outside of the gravitational pull of the galaxies themselves.

An easy read on intergalactic findings:
https://www.thoughtco.com/what-lies-between-galaxies-3973588

So far, though, we are only able to see and account for the 'stuff' between galaxies -if- it is warm enough to radiate. It gets warm enough to radiate if/when a galaxy passes through it. But - we cannot say if or how much matter there is in the cold stretches between the galaxies. There is a lot of conjecture of how much mass there is - but a lot of assumption that there is mass there. All it would take is 2.5 cold Hydrogen atoms, essentially individual atomic Bose-Einstein condensates, per cubic meter within the visible universe - which would be completely undetectable using today's telescopes to make "Dark Matter" and "Dark Energy" fall out of the equation.

 

[daveshah]

Well, the Pyra is still in Nürnberg yet Fedex are still claiming it will be delivered today...

Whilst one visualises specially charted jets and motorcycle couriers waiting on the runway, this also seems unlikely. I suspect it will now be delivered Wednesday at the earliest.

 

[ClockworkCoder]

Well, the Pyra is still in Nürnberg yet Fedex are still claiming it will be delivered today...

Whilst one visualises specially charted jets and motorcycle couriers waiting on the runway, this also seems unlikely. I suspect it will now be delivered Wednesday at the earliest.

This is one delivery that's causing many of us to become tense!

 

[levi]

Yes, it really is a trial. Not quite the Nurnberg trials but there you go.

 

[λ the β-Redex Reducer]

Well yes. As soon as something becomes true (I'm not sure what you mean by 'justified' there, unless it's a common english idiom), you no longer have to believe in it. Very little stuff in science actually becomes true, rather than extremely highly probable, so it's rarely a problem in practice.

Justified in this case means that it is backed up by evidence. Justified true belief is not an oxymoron, it's just the epistemological stance that knowledge are beliefs that are true and backed by proof or evidence.

Also, what do you mean by becoming true? Do you think/believe/know/accept/acknowledge that reality needs an observer to exist and that things become true as we observe them? So if a Pyra gets turned on in Germany, but no one is around to see it, then it does not emit any light?

 

[ible]

So far, though, we are only able to see and account for the 'stuff' between galaxies -if- it is warm enough to radiate. It gets warm enough to radiate if/when a galaxy passes through it. But - we cannot say if or how much matter there is in the cold stretches between the galaxies. There is a lot of conjecture of how much mass there is - but a lot of assumption that there is mass there. All it would take is 2.5 cold Hydrogen atoms, essentially individual atomic Bose-Einstein condensates, per cubic meter within the visible universe - which would be completely undetectable using today's telescopes to make "Dark Matter" and "Dark Energy" fall out of the equation.

you need dark matter inside galaxies to explain their rotation curves. the stuff outside doesn't help with that.

also, 2 hydrogen atoms per cubic meter doesn't seem like a lot, but the cross section when looking through the vastness of space would be non negligible. it would interfere with telescopes, and also put out hydrogen spectral lines, more than what we currently see.

 

[lordbobjones]

It has been a while since I studying Dark Matter/ Dark Energy. Are they still thinking that Dark Energy is going to drive the expansion of the universe for an infinite amount of time? That was my take back in like 2000...

Time to do some reading to see where things stand today.