Q&A 142: Do Pulsars Slow Down? And More...
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- čas přidán 28. 06. 2024
- In this week's questions show, I look at the rotation rate of pulsars, why NASA is such a fan of the term in-situ and what our plans are for exploring the Universe.
00:00 Start
00:49 Do pulsars ever slow down?
03:20 What's with in-situ?
05:17 Europa or Enceladus?
07:42 How far could Starships go?
09:27 Can planets be in orbital resonance?
10:44 Would fusion work for space travel?
12:46 What are the plans for colonising the universe?
14:26 How soon until we can starhop to another star?
16:17 Why isn't there an improvement to the Drake Equation?
19:28 Why don't we use nuclear rockets?
23:48 Could we use binoculars to see the night sky?
26:35 How close are stars in a cluster?
27:57 Best way to terraform Mars?
30:18 Why not use wiper blades on the Mars rover solar panels?
33:19 Is there bacteria on the Voyagers?
36:01 Is dark matter a fact now?
40:11 Is there confirmation bias in the science community?
Want to be part of the questions show? Ask a short question on any video on my channel. I gather a bunch up each week and answer them here.
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You are free to use my work for any purpose you like, just mention me as the source and link back to this video. - Věda a technologie
Q&A are the best. Im learning more than ever in school. Dont care much for the interviews.
Totally agree, school only teach ya what you need to know to pass an pointless exams, better exam results means more funding and higher profits. They teach very little of what you need to know for life.
@@MxWintersAFOL Not only that, but they don't teach you what you _want_ to know in life either (for most people, like those who don't spend the first third of their life doing the same song and dance, to pass the same types of exams, in ordee to _then_ have a _CHANCE_ of getting into some super specialized doctoral program [that'll probably *still* not teach them what they need and truly want to know in life], and if they were Americans, they'll have to take out hundreds of thousands or over a million dollars in student loan debt, that'll take really just an infinite amount of time to pay off, which means you'll be spending your time, energy, and resources working and NOT saving due to your debt bills, which itself will mean you won't get the free time to ACTUALLY self-teach yourself what you need in life, or what drives your passions in life]).
And look, getting a decent education is extremely important, but school'll never be taught one of the most important things you'll ever need-how to think critically.
They'll teach you what to think, but not _how_ to think.
So, it is science that showered us with gifts? Fraser the Philosopher. Well, yeah. That's why we like your channel. Thank you.
great video, always love the Q and As
19:25 "the number of civilisations in the Milky Way could be zero, or it could be 400 million"
I am existentially alarmed by the suggestion that it is zero.
Well done. Existential alarm is an important part of science. It means you are accepting that something which could shake your existing views may actually be true. :-)
Love the q&as, keep it up!
I just saw James Cameron on Breakthrough Discuss 2021. He would be a good interview guest.
Why?
@@LarsRyeJeppesen Talk scientific accuracy in movies? Or just geek out on SciFi :-)
Good show
What makes the Drake equation meaningful is that no guesses come up with "Identically zero" as the result. So the takeaway is "Threy ate likely, 'somewhere'..."
Hello Fraser, In Q&A 142 you explained how pulsars slow down. You did not mention their speeding up. My understanding is that speeding up is caused by conservation of angular momentum from matter being accreted from a companion red giant. My questions: to what degree do the speed-up and slow-down offset each other, and in such cases how do astronomers calculate the age of the pulsar? Thanks!
I'll be checking back in in 10 million years to get your opinion on where we are at in galactic colonization. Will you be on your 5th or 6th robot body by then?
I'm gonna spring for the deluxe jar, Dolby 87.4 speakers, and a flexistraw!
I have the same binoculrs as you. Good for stargaze and also good for learing starmap.
In! Sit! You! A disturbance in the force, felt I did.
As a science-communicator you keep us informed about recent developments in space & astronomy - in your opinion - what is the most underrated "hot topic" right now in the general public? What are you the most excited about?
Oo. Oo. I have a question! Two questions, even!
An astronomer sees a distant galaxy by light that traveled for 800 million years.
1. What was the separation of the Milky Way from that other galaxy when the light was emitted?
2. What was the separation of the Milky Way from that other galaxy when the light was observed?
Regarding the neutron star spin rate, if it acquires more mass then it should shrink further, thus increasing its angular momentum?
Regarding nuclear fission reactors, I think it's feasible to develop, with the current technology, a dual-purpose one, for both propulsion and electricity generation. The thing is, nuclear-thermo is the only propulsion system with a thrust/mass ratio in the same ballpark as the chemical rockets while having better ISP.
What would you say are the top three things to see/do on the island you live? Chance for a non space question if you want
You touched on a question I asked in a comment once - why can’t you mine uranium from asteroids? Is there some reason that the heavy elements we need for nuclear power or not available beyond the earth? What about other planets?
Solar thermal can easily be switched to electric propulsion by moving the engine out of the mirror's focus and moving solar cells for concentrated sunlight such as those made by SpectroLab, into the focus. Bimodal nuclear fission is not so easy. Solar thermal can get the spacecraft from LEO to escape in a week or two and still take advantage of the Oberth effect and then the ion or other electric propulsion can catch up to and pass the NTR on the way to Mars, I was told at a conference that the problem with solar thermal/electric is that it doesn't cost enough to interest contractors.
Q: if it is so that colliding black holes manage to move the fabric of space itself it and we can detect it I would assume we could also detect how we move trough the same fabric of space?
And, if space is expanding, there must be a direction of the expansion?
And when we move trough space we should be able to determine the direction of the expansion?
And also, if we manage to determine the direction of the expansion, we should be able to figure out where in the universe we are? Or what?
We pronounce ITER like eater. I work on it, among others. I develop simulations and control systems for tokamaks.
10 million years to populate the universe I definitely want to be here to check that out and let you know if you're right :)
I had read that neutron stars are so uniform they do not give off gravitational waves.
I think you’re right. Slowing is probably caused by the energy expended in producing the pulses.
@@douglaswilkinson5700 That was my take on it too.
Your response to bacteria on Voyager made me think of an article I read a couple years ago, maybe in “nature” or “science” about mold on the ISS. They have Aspergillus Niger mold (if I remember correctly) that can’t be killed by radiation. Is anyone taking into account the fact that these molds produce mycotoxins and spores that are dangerous to human respiratory and nervous systems? If we start a moon base or Mars colony, will humans survive the trip only to be given other diseases by molds that we bring from earth?
@FraiserCain @21:50 en.m.wikipedia.org/wiki/Nuclear-powered_aircraft
Beat me to it!
Dark matter is the molecular components of such objects as Love, Justice and Compassion...
20:16 Well, I've just read the headline "DARPA selects Blue Origin, Lockheed Martin to develop spacecraft for nuclear propulsion demo".
Hi Fraser! Everyone dreams about terraforming Mars, but adding enough atmosphere there would be a nightmare. Would Venus be a better planet to postulate terraforming? Perhaps removing atmosphere would be easier than adding it?
What would be more interesting to find: alien life with DNA/RNA, or without?
Nuclear Thermal rockets (19:28 - 23:28) have so many advantages; I don't see why time would defy their eventual use. Sure, there is danger in launch and re-entry into the atmosphere. What puzzles me is why there isn't a program somewhere to tackle that problem with enthusiasm. Why give up before you start? Ion engines are great but have the drawback of weak thrust. I envision a combination ion/ntr rocket ship that would benefit from the strengths of both. As for chemical rockets being cheaper once on-orbit re-fueling and in situ utilization becomes a thing...perhaps. But a NTR still has fundamental advantages in terms of specific impulse. There's really nothing except perceptual prejudices stopping a wide range of propulsion systems --- including NTR --- from becoming real things in the not too distant future.
Follow-up question from the livestream; How would a LUVOIR deep field compare to a Hubble and Webb deep field?
Webb is infrared
QUESTION 🙂 Is there a known type of event which could produce gravitational waves that could be felt be the human body if you get close enough?
Thanks love the show!
Hi Fraser. Follow up question. On sending a Starship to Jupiter. Would we need to wait for Jupiter to be in a favorable position like we do for Mars? It would seem to be a long wait for Jupiter to come around to a precise place in its orbit.
Yes, we do need to wait for the right alignment, but remember that Earth also revolves around the Sun, so in the end we only need to wait a little over a year between each transfer window. In fact, we need to wait less time for Jupiter than we do for Mars!
Have we found signs of uranium on the moon or in asteroids or on other planets? Could we launch refinery equipment into orbit and refine fissionable material in situ?
I saw a vídeo from sixty symbol That said That nêutron stars are incredibly smooth and, because of That, a single, alone pulsar doesnt emite gravitacional waves. Is That correct??
Greetings from brazil for The amazing work
An in LEO refueled Starship, without any cargo, has about 8.5km/s delta-v. Assuming Starship is supposed to return to LEO, a roundtrip-rendezvous mission to Jupiter costs about 7.0km/s. You also need fuel for mid-course corrections. And the speed when it arrives back at earth will be enormous, ca. 15km/s at best if not higher. A single aerobrake manouver won't be enough to get captured by earth. So Starship needs to plan a burn here too and orbit-insert burns are expensive as well.
So I don't think Starship can easily be thrown around the outer Solar System. Not if it is supposed to enter an orbit at its target and return to earth afterwards. That's the difference with existing missions. They usually do fly-by's and don't ever return. And do not hold cargo and perhaps LOX for 5 years.
But is is close to possible. The ejection burn to Jupiter consumes most of the delta-v budget. The return trip is surprisingly cheap, because Starship would fall inwards to the sun on it's way to earth and doesn't need to burn for that. But at earth arrival, it has to slown down.
Here's the mission I used as a reference, calculated by NASA: trajbrowser.arc.nasa.gov/traj_browser.php?NEAs=on&NECs=on&chk_maxMag=on&maxMag=25&chk_maxOCC=on&maxOCC=4&chk_target_list=on&target_list=Jupiter&mission_class=roundtrip&mission_type=rendezvous&LD1=2021&LD2=2026&maxDT=5.0&DTunit=yrs&maxDV=7.0&min=DV&wdw_width=0&submit=Search#a_load_results
Gravitational waves? I thought it was drag from the magnetic field interacting with gas/plasma around the pulsar?
Does a rotating body as perfectly spherical as a pulsar generate gravitational waves? I guess if you think of "chunks" of the pulsar rotating about it's center then there is moving mass.
I would imagine that for every such "chunk" there is a diametrically opposite and identical "chunk" that would generate opposite waves so the total external wave would be aero, but maybe the energy has still been expended?
I've always wondered if our solar system was unusually isolated - being over 4 light years from the next star. Obviously, stars are denser in the centre of the galaxy, but out where we are, is 4 light years a typical distance?
Magnetic-reconnection engines: How much better would they be than Hall-effect thrusters?
What if the neutron star's axis of rotation is balanced? Would the star then not emit appreciable gravitational waves?
Q: Why is NASA such a fan of the term in-situ?
A: Having another vowel is helpful in creating a good acronym.
Question: why do space agencies only make 1 of every type of probe. Surely if your creating a mars orbiter for example the same probe would do the same job on venus, jupiter, any of the moons in the solar system etc. Wouldnt we learn more for less cost per target by creating a generic planetary orbiter and mass producing them and sending them out to all the targets we want to study.
Why you stoped doing topic explaining videos?
I hardly missing that
Hey Fraser I have a question! How long would it take for every trace of human activity to be wiped off of Mars? Millions of years? BILLIONS? Would our stuff stick around longer on the moon?
@ᴡɪɴᴛᴇʀᴍᴜᴛᴇ _ Great response. Thank you!
Hi Fraser! re: nuclear rockets. Could we break up these rockets to be sent to orbit in multiple pieces in such a way that an accidental explosion would not lead to dangerous radioactive fallout?
Hey Fraser, I know we have tracked all the possible asteroids that could hit earth over the next hundred or so years, are we tracking the same possibilities for mars? Would be a shame to land there only for our "backup plan" to be taken out by an asteroid/comet.
Seems like a lot of moons and planets have this loose and dusty regolith that could be made into living soil. Yes, the very top would not have life because of the vaccum of space and also the solar radiation. But, maybe a little bit deeper a "micro bio zone" could be built...then we could grow space turnips!
Why the neutron star diagram shown in the video has no neutrons in any of the layers? Wrong picture perhaps?
As per the outer space treaty, satellites and spent rocket stages left in orbit belong to the country that sent them up. What happens when that country doesn't exist any more?
When I was a kid I thought nuclear energy was nuclear explosions in giant pistons. I was really disappointed to find out the truth.
Errr, does a pulsar NOT in a binary system actually lose spin through gravitational wave radiation (as you suggest)?
I thought these things were crushed into incredibly symmetrical spinning bodies and so (without any CG motion) wouldn't generate gravitational waves.
(frame-dragging OR magnetic interaction with interstellar matter might cause some energy losses)
what's the earliest point in time where a civilization such as ours could've formed?
Per Isaac Arthur the galaxy had a high enough metalicity to start forming Earth-like planets when it was about 8 billion years old. Check put his channel for additional information.
Hey Fraser, why are Miss Universe contest winners always from Earth. Seems kinda unfair! Drake (not the rapper) and Fermi would be outraged! 😔
How would the sky look like from outside the Milky Way, like half the distance to Andromeda in a very quiet zone?
(1:13) _Smushed_ together, not _smurshed._ _Smurshing_ is what happens at the beginning of every James Bond movie.
How do I know? I attended a circa 1980s lecture by Dr. Fraknoi´s at Cañada College in California, when he was one of the early and few to discuss black holes... by describing them frequently and consistently as _smushed._
And they say that physicists have no sense of humor....
So when neutron stars slow down by emiting gravity waves we can consider the gravity field as a medium with friction!
No
my son says "dad. rockets are dead. space planes. that is the way its gonna work". graduates with his aerospace engineering degree in 4 months.
I Should point out that the Soviets have orbited more than on nulear reractor, ll without the benefit of ceramif high temperaturer gas cooled tefdhnology. Programs like NRVA were amimeed at high-thrust rkdket-like rofkertsd. Toeay, what you want is a gas fooled pebble bed rector - inherently mufh safer than a flad fuel earthbound water or graphite moderated reactor, and then use water as the propellant gas because low molecular mass, easy to get. Then aim for maybe 0.25G acceleration for a year or so. Plan on refueling the propellant, but not the reactor itself. This is a much easier problem than 3500° NERVA style rockets.
@Fraser Cain My idea for Starship legs would require a somewhat long video with examples, sources, and graphics, that's why I was thinking about asking an already established channel like Smallstars to help me out or collaborate with me, they have a Patreon just for that (to develop ideas) and I think Elon watches some of their YT videos and animations, but I'm not sure if they'd like to, since they never responded to me.
I don't have a Twitter, I got banned lol - If I end up making a video on my own, could you guys maybe help me show it to Twitter? Idk, I don't even have a space YT channel, to promote a video. Some people told me it was best to write a letter to Gwynne Shotwell instead, that's why I was asking for your advice. Thanks.
As Andromeda gets closer to the Milky Way, will it ever reach a point where it's bright enough to see with the naked eye?
I think you can technically already see it with the naked eye in dark enough skies, although I've never seen it. It'll get gradually bigger and brighter over the next couple of billion years, make sure you upload yourself to the cloud, and put the date in your calendar!
From a dark sky site, you can. It was a bit difficult. We went to the McDonald obseratory in west Texas and we were able to see it by looking just off to the side of where it was and then focusing in on it.
32:40 I suggest giving solar panels track & tilt ability. By tilting the panels steep enough, the dust should slide right off. Opportunity actually had some sand slide off its panels on a steep slope (mars.nasa.gov/resources/7782/streaks-on-opportunity-solar-panel-after-uphill-drive/). Tilting the panels would also allow you to track the sun, so a bonus I guess.
Why is JUICE not focussed on exploring Io?
Could dark matter exist in what ever you'd call the "space" that the universe has expanded into? And dark energy? Could the universe be like a wave flowing over a strange preexisting universe?
Ps- Love these q&a's. thanx.
7:00 I'm not sure but in the book 2001 A Space Odyssey the message at the end was to not land on one orbiting Saturn, while the movie had the message concerning another orbiting Jupiter.
Don't go to either? LoL
One's a book, the other a movie, both are fiction, great science fiction, but fiction nonetheless!!!
Oh, and I read the book after having seen the movie and they are both very different from each other, in my opinion. I was actually shocked after reading the book how different it was.
@@mattpotter8725 It's a joke, LoL . I had that at the end.
@@ProperLogicalDebate Ok, but my point about the book and the movie being very different beasts still stands regardless of your 'joke'.
@@mattpotter8725 I agree. I understand Arthur C. Clark collaborated on the movie and then wrote his own ideas in the book. The movie went to Jupiter because of the cost of duplicating Saturn's Rings.
9:00 claims that a fully fueled Starship in Earth orbit could go “anywhere in the Solar system.” That’s not true. A Starship with no payload is projected to have a delta-v of about 8.9 km/s. With 100 tons of payload, it’s about 6.9 km/s. Even with no payload, that’s not enough to fully reach anything but Venus and Mars. Technically, a no-payload Starship could achieve a very high orbit of any of the outer planets, but it couldn’t achieve a mid- or low-orbit of any of them, or achieve orbit of any of their moons. Mercury would be completely out of reach. (If you’re willing to take years extra to get some gravity assists, more would be possible.)
I think I have seen this one before...
It starts off live and then he uploads an edited version.
You were probably there for the live show. :-)
Everything screams it's time for a base on the moon. ;)
It's interesting anyone notice mostly men are subscribers !!
What if dark matter is just aliens using advanced cloaking?
Dear Fraser
I hate to say this, but *I think* your answer about fusion is incorrect. I don't think fusion/ fission/ antimatter would be suitable means of propelling a spacecraft outside of an atmosphere.
The reason nukes are so devastating is because of the interaction of the heat energy they release and the atmosphere which has to deal with that enormous release. They create an *Atmospheric* shock wave. If there's no atmosphere, there's no shockwave. If you're in space and you detonate a nuke, it will release an incredible amount of heat, but there's be no shockwave. No expanding gasses. Nothing that will cause a spacecraft to move. You could detonate a thermonuclear weapon outside of the ISS and it wouldn't move it at all (though it would likely melt large parts of it and irradiate the crew).
I've been bringing up this issue for years, in relation to the Orion spacecraft. I've yet to hear anyone offer any indication that my information is wrong. Now I'm not a physicist. I'm a chemist (and all chemists have to be part particle physicists/ part nuclear physicists), so I have some familiarity with the way nukes and propulsive systems work. And as far as I'm aware, any fission/ fusion/ antimatter engine for any spacecraft would fail to move that spacecraft, if it's not operating within an atmosphere. It would make more sense to use a fission/ fusion/ antimatter reactor to generate power and use that power to run a Plasma Engine (though you'd need some other propulsive device to reach orbit).
I'd be thrilled to find out that I'm wrong, but I'd need an explanation of exactly how I'm wrong.
Additional:
Nuclear Thermal Rockets are different in that they don't use a nuclear reaction to generate propulsion. They use a nuclear reaction to generate heat and they use they heat to accelerate a liquid through a nozzle to generate propulsion. Realistically, you can use anything to generate that heat that drives the propulsion, it doesn't have to be a nuclear reaction. I'm referring instead to the idea of using nuclear reactions to directly drive the propulsion, which as far as I can tell, will not work in a vacuum.
@@Raz.C Isn't the point that any form of space based propulsion system, apart from solar sails that is, use a reaction, whether chemical or nuclear, to push something out of the back of the spacecraft whilst in an environment where there is some gravity to propel it forward. I understand what you are saying, but no system we have would be able to speed up any spacecraft if it is at rest halfway between Earth and Mars for example so any speeding up by any acceleration by a propulsion system has to be done in the vicinity of Earth or some other planetary body. Once out in space it will just continue accelerating at the rate of the push you have it in the first place. This is why for example the Voyager spacecraft used gravitational slingshots around planets to gain speed and send them on their way to their next destinations as quickly and efficiently as possible.
I agree with Fraser in that he doesn't see how just detonating an uncontrolled nuclear bomb would help, you need to control the reason and harness and direct the energy from the reaction, and I understand his point about the risks of sending into orbit fission based rockets if they exploded. I'm surprised that he didn't mention the fact that the mass of the reactors, whether fission or if they manage to get a functional fusion reactor, is going to be a huge problem. We have sent things into space that are nuclear powered, we just don't use them to actually get into orbit. I believe the Voyager spacecraft were nuclear powered, although that isn't destined for another planet so I guess that's not a problem. I seem to remember other probes are nuclear powered we well, I think the Viking landers on Mars were, aren't those the ones used in the movie The Martian to keep Mark Watney alive by powering his rover and able to get him to the site where he can launch off the planet?
@@mattpotter8725
Hi mate
I don't know if we're on the same page, so I'll take it slowly.
Ok, if we're at the Earth-Sun-L1 point and we fire chemical rockets, the expanding gasses as well as the velocity of the ejected (expanding) gasses will result in forward momentum.
If we're at the Earth-Sun-L1 point and we use an Ion Engine or a Plasma Engine, the acceleration and ejection of the ions creates a forward momentum.
If we're at the Earth-Sun-L1 point and we detonate (Project Orion type engine) a fission bomb in the nozzle area of the engine, there's no expanding gasses, there's no significant particle acceleration, there's no medium by which to create motive force. This is the same whether we use a fission device or a fusion device or an antimatter device. This is true whether we detonate a bomb (fission/ fusion/ antimatter) or whether we're able to control the reaction the same way we currently do in nuclear energy plants.
Currently, when we send nuclear powered craft into space, the nuclear reactions generate electricity and/ or heat, not motive power. So it's essentially a nuclear battery, rather than a nuclear engine.
The idea behind the Project Orion spacecraft, for example, would work fine if we were to use conventional explosives. The idea being that conventional explosives rely on the rapid expansion of gasses. A spacecraft can use this principle to power a spacecraft. For example,
If we're at the Earth-Sun-L1 point and we use conventional explosives to power a Project Orion spacecraft, the expanding gasses will be focused and forced out of the nozzle, creating motive force, resulting in the spaceship moving.
Ironically, if we use nukes or conventional explosives on a Project Orion spacecraft, *within the Earth's atmosphere,* the craft will not have any motive problems. If we achieve orbit with our Project Orion spacecraft, using conventional explosives will still allow us to move our spacecraft any way and any where we like, however, if we use nukes instead, we no longer have any ability to generate any motive force and our spacecraft is now stranded.
OK, I hope that makes sense.
Cheers,
Raz
@@Raz.C I've only scan read this so will to through more thoroughly later and may respond again then, but in short what in saying is that what method of energy generation you use, whether chemical or nuclear you have to use it to push something out of the back of the spacecraft to propel it forward, which is possible with nuclear even though may be less efficient compared to other means, but it's not impossible to convert the energy to the exact same means as chemical engines use. I imagine those smart people at NASA crunched all the numbers and it came out that nuclear power just want as efficient as chemical, although it has advantages that it can last a very long time whereas with chemical engines you have to carry your fuel with you which is heavy and once used up is gone.
Could You please tell to dr. Pamela that 40 seconds long intro videos(CosmoQuest) are boring, absolutely unnecessary and a waste of time.
Your channel does not have any intro video and that is just perfect. People want to see interesting content and that's what they get.
Fraser, I have a Masters degree in Physics in which I did some astronomy, although I will admit I have worked in computer science after graduating, but I'm not yet convinced by Dark Matter. I respect physicists who are working towards trying to find out if it exists, but I'm concerned by your response because from all my years studying physics we were taught to be sceptical about everything until something can be proven by repeatable independent verification.
I don't think the scientific method is just about having to prove something is wrong, but until we actually know what Dark Matter is I'm sceptical about it. I'm sceptical of other attempts that involve not having Dark Matter to try to explain what is going on, I don't know what the answer is (that's how science is), but until Einstein (and others) came along the scientific community believed that Newtonian Physics explained everything and whilst his equations still work under certain circumstances they don't tell us the whole picture. The same with the the expansion of the universe, it was thought before Edwin Hubble that it was in a steady state, most scientists believe this.
The problem is that the universe is hard for humans to think about on such large scales where relativistic effects come into play. Maybe under certain extreme conditions that we haven't considered and tested things like gravity behave differently. Sure the evidence points at Dark Matter exists, although we have no proof that it does yet, and until we do I, as a person with a scientific mind will keep an open mind, as everyone should. And if we find what Dark Matter is then great, but we should be open to other possibilities as well.
@ᴡɪɴᴛᴇʀᴍᴜᴛᴇ _ Did you read what I wrote?!!! I'm keeping an open mind, but not preempting anything. In the world of physics many theories that have had a lot going for them just haven't been borne out by years of work. The way the world works and even the universe is a lot stranger than our everyday experience.
@ᴡɪɴᴛᴇʀᴍᴜᴛᴇ _ Exactly, it's just that without the evidence for what Dark Matter actually is it could be explained by things we just haven't thought up yet. Before Quantum Mechanics we had unexplained phenomena, but no one ever thought something as weird as it would explain them. I find it hard to believe there is a particle we can't find that interacts gravitationally with baryonic matter but doesn't in any other way. I think we just don't really understand gravity completely yet. It is thought to have the graviton as it's force carrier just as the other forces have their force carriers yet it is impossible to experimentally confirm they exist. If it's not possible to do this then where does science go from there, which might be the same with Dark Matter? So we just assume it's right and build on it?
I'm not saying either of these aren't right just that because there's a theory that explains phenomena doesn't mean that it's proven without experimental evidence to back it up. So I'm sorry if I don't fully believe as truth anything without experimental evidence as either it can't be proven in some cases (which is purely theoretical and doesn't sit well with me) or it just hasn't been proven yet beyond doubt, and whilst that's the case I'll keep an open mind on other theories. I don't see this as an unscientific approach.
@ᴡɪɴᴛᴇʀᴍᴜᴛᴇ _ You are right in that we will never be at a complete understanding of how physics works and if will only be an approximation to reality, I didn't claim that we could ever get to that point, just that we have experimental evidence for what is proposed. Evidence of absence shouldn't be confused with absence of evidence.
In the end your statement saying we can rule out what it isn't only stands if there isn't presented a complete paradigm shift, as there was when Einstein put forward his Theory of General Relativity. Before that you could have said certain things weren't true just because we made assumptions about the universe that changed with a new way of looking at the universe, and the experimental evidence to back it up.
Now, I'm not saying for over second that Dark Matter doesn't exist and all the papers that have been written about it aren't true, there is massive funding going on the direction of finding it, just that until it is definitively detected I'm sceptical. The thing is that I've seen with other theories, especially those in quantum mechanics theories become popular, but they become almost impossible to prove with experimentation, and when that happens where does that leave us?
We assume that physics as we see it on the Earth and its surroundings are how it is everywhere in the universe. What is that isn't the case with the constants we see as constants not being constant? I think there are many, many surprising things we are yet to discover, just as crazy as when Einstein presented his theories that astounded the scientific community.
Progress in science isn't linear, you can't just put a few hundred more people on studying various areas of it and get solutions to what you want to discover, it rarely works like that. It quite often takes one person (or a small group) to put forward a theory and from that it grows. Even with all the evidence pointing towards it in yet to be convinced that Dark Matter exists, but as I'm a scientist at heart I'll gladly be proven wrong, and will keep an open mind in the meantime.
@ᴡɪɴᴛᴇʀᴍᴜᴛᴇ _ I agree with a lot of what you say, but in the intervening period between proposing a theory and it actually having experimental or observational proof to back it up it can't just be assumed to be true. I just have a hard time believing that there's matter out there that interacts gravitationally, but doesn't interact in any other way and therefore is so difficult to detect. I believe that there will be some new physics we've yet to discover that plays a part here at relativistic speeds or at a quantum level even if there is. There is much more to this I think than just undetectable matter in my opinion, but I'm happy to be proven wrong.
Where is your math? How can we test your "theory"?
37:40 Dark Matter is a great name.. just saying.
Wake up
To what?