When I was a kid, the 200-inch Palomar instrument was the largest, best telescope in existence. It was thought to be at the limit of what was possible for ground-based astronomy. Anything larger would certainly warp under the immense weight. Decades later, that idea is laughable. Segmented mirrors, adaptive optics and digital signal processing have absolutely revolutionized what is possible with ground-based astronomy. Combine that with the various space-based instruments, and it is no exaggeration to say that astronomy has advanced by orders of magnitude from the days when it was all about observing individual objects, one at a time. An astronomer from the '80s would be utterly shocked at what is possible today, and at what we have learned. It's a pleasure to hear from Dr. Moustakas, as always. His focus on maximizing science returns is interesting. He must be a great inspiration to his students.
I wish I could afford to donate. This was one of the most educational videos I've ever seen on RU-vid, so much connected information. Thank you Frasier. I love your work.
Question: I am from the northern part of Iceland, many times in my life I have been driving through everything between a light snowfall and blazing snowstorm. While driving in those conditions, I have often imagined that I am flying tremendously fast through the Milkyway galaxy, imagining that every single snowflake that I am hitting and driving past is an individual star. I have often been curious to know how much snowing area on earth would represent the entire galaxy and how far I'd be driving through it in an hour or so. To make it short: If I´m driving through a snowstorm (at about 90km/h) and imagined every snowflake to be a star in the Milkyway galaxy, how much distance in light years would I be traveling in a time of your choosing? Is there any possibility you could shed some light on this?
@nycgweed I suppose you're right😄 I didn't really think that part through🤔 I guess it's somewhat an unanswerable question. Snowing conditions can vary quite a lot, and one would drive at different speeds, depending on amount of snowfall and wind speed. You'd have to find out some specific parameters to work with. Like the amount of snowflakes per cubic meter, the speed at which the car is hitting and passing the snowflakes, perhaps the average distance between snowflakes?🤷♂️
If it's about 1cm between snowflakes, then the 60,000 light years of the Milky way might be anywhere from 15000 to 60000 cm? 150 meters to 600 meters? If it's 3cm between snowflakes, multiply that by 3.. and so on
Consider using the database in the game to calculate the current positions of the galaxies today, assuming the known coordinates data is red shifted by x, and reporting that back from the game players pc.
If galaxies further away are further apart, but nearer galaxies are cl;oser, does that not imply - due to time dilation - that gravity is gradually pulling everything together, not dark energy pushing everything apart ?
If they found something extremely interesting would it first have to collect all the data and years later after analyzing the data find the object or would they know a weird object was detected real-time?
I want someone to make an interactive map of the CMB that shows us how it really looks from, say, the center of the Earth as you twist around. By moving around your view you can get a completely non-distorted and unbounded view in all directions that makes a lot more sense than the rectangular one we see all the time. I think someone will make a lot of money when they produce a much better map of the CMB that shows us what it really looks like.
No, no, that is NOT the largest map of the universe. *I* have the largest map of the universe. I keep it _everywhere_ (with a humble nod to Steven Wright)
I think I am with you on this Mr Cain. I think dark energy is weaker and constant than gravity, we(the Milky Way) are bound to our local galaxy cluster and then the Virgo cluster, the dark energy is inherently found in spacetime itself but the wells of gravity overcomes dark energy on the inverted radius squared basis.
The Hubble expansion of space dominates over gravity when galaxy clusters are separated by at least 300 million light years but dark energy doesn't really influence the Hubble expansion all that much but starts to dominate on distance scales of several billions of light years, but in the future (say 10 billion+ years) it is predicted to accelerate the expansion by a much greater fraction.
If the "big rip" is not a thing due to gravity within galaxies being stronger than dark energy, surely this should mean that the "dense" early universe should have exerted enough "gravity" on itself due to matter being "close together" which would make the effect of dark energy less in the early universe and stronger as galaxies move apart and experience less gravitational pull from each other? So dark enery should be "weak" early on and "stronger" as the distances increase. Dark energy should be a constant, minus gravity, thats why it seems to increase as the size increases. The effect of gravity slowing dark energy down would decrease. Is this not right?
Yes dark energy has a constant energy density in space, so as space expands the amount of dark energy in the universe increases and now dominates the energy content of the universe by a ratio of 7 to 3.
we see the efects of gravity, on a planetary scale, dark mater, do we see the effect of dark matter, or could this be something else we just havent considered, what could that be, well not worms, i would go more what we know, fields, some kind of electromagnetic field, so eek, we cant see it yet, but like gravity, also a weak force, maybe its there and acounts for a lot or something, field interaction at atom lvl could be a game changer.
the invisible energy could be upto 99.9999999 % not to say all what is in the universe and would not differ even there would be BB's everywhere a balance between energy and matter , but still all objects big or small contains this energy , but in this form different from the general forcefield , so what we observe is energy rolled up like a plots of wool all these stuck in-between the surrounding forcefields
Ho Fraser, considering Euclid is cataloging a large oart of the universe, is there some sort of international coordination system for space, and if so, what is ' zero'? If there isn't such a system, how does the catalogue work?
Most charts I’ve seen use either Sol or Sagittarius A* as 0,0,0. Any chart we make has to have some sort of vague meaning or reference to us. There is no true objective zero point, since every point in the universe was the zero point at the Big Bang. I suppose if we ever nailed down the precise gravitational center of the Great Attractor close enough to use it for a chart, it could make sense to use as a zero point. But, Because of expansion, Sag A* will always more or less (+- it’s future interactions with Andromeda’s galactic center) be the “center” of the universe that we could ever possibly reach. We will eventually be too far from the Great Attractor for its pull to overcome expansion, so our galaxy won’t ever “get there.” Making it less attractive as a zero point.
Starlight broken out along the spectrum has dark bands corresponding to light absorption, some at the source, by various molecules. Those bands move with our relative speed toward or away from the source, sort of. The overall balance may skew red or blue but the starstuffs will take their little slices at exact wavelengths. Fraser talked with someone who studies our sun and there's a very clear example of those absorption bands shown during the conversation.
Random question. If the universe is expanding faster than light, does that mean would we be able to see where the milkyway form or will the light never reach us.
We already see where the milky way galaxy formed, right here! Only the distant universe is expanding away from us faster than light, everything beyond 9 billion light years distance.
Question: Is Dark Energy isotropic? The CMB and Dark Matter both have structure. Do we know for sure that Dark Energy is uniform? Maybe expansion can also "clump" in some way?
It is predicted to be isotropic, and some studies have suggested it is isotropic and some have suggested there may be a direction where dark energy is higher in value. Large scale surveys should resolve the issue.
Last comment, I promise. I am glad the focus is on dark energy for a change. Say what you want but we are slowly chipping away at the dark matter and dark energy mysteries. Instead of engaging in armchair philosophy, Cosmologists go out and actually look!
Sadly, it could be another 500 years until we actually crack the mystery. My bet is on Modified Newtonian dynamics atm. Maybe the reason we see nothing is because nothing is there. We just don’t understand gravity well enough when it is at the galaxy scale
Does anyone know what/why happened to the video about the anti-matter drive from about a week ago. I watched half of it then when I came back to it the next day it had been taken down. It was fascinating and wanted to look up the guy being interviewed to find out more to see how legit he was.
@@frasercainWasn’t it just an Orion Drive with bigger and more numerous explosions? We know how to make, and how to store antimatter. It’s not energy efficient to make the fuel, but, it is extremely storage and weight efficient, which is much more important for space travel.
For Frasier. Lets say we are at stardate 13.7 - or BB 13.7. Could there be potential civilisations like us a million light years away - right “now” - but there is no way to see their technical signatures for at least a million years?
The speed of light says yes. There are two confounding factors. First our current telescopes could not detect them at that distance unless they were were doing Dyson sphere level engineering. Second, civilizations develop over time. So when we could detect them would depend on how how good our telescopes were and how big their techno-signitures were.
Why a neighboring star? Just send it all into our own sun since we have the tech for that now. Of course the trillions of dollars to do that could be better spent on breaking down everything here and of course developing the tech to keep us from just making it a mess again.
We can, in fact we could throw it into our sun. The issue, is the fact that it is super expensive to do so. We put trash in landfills because it’s cheap and out of sight. If we wanted to throw trash into the sun it would cost billions of dollars. Currently it costs around $1,800 to put a pound of matter into orbit, and that’s not even considering the flight into the sun itself. So at the end of the day it’s possible but not plausible. We’re much better off repurposing the trash instead of throwing it into the sun.
I love BAO, it is amazing we were able to observe them, since they require so much precision. Also BAO are degenerate with respect to H0 and rd so you cannot use them alone to solve the problem with the tension.
The Hubble constant (confusingly it is not a constant in time but everywhere in space at a certain time after the BB, so over time it has changed and so is also called the Hubble parameter) is the measurement of the expansion rate that exists at this current time, and we can understand how this has changed since the big bang, the expansion rate slowing down over time from maybe 1500km/s/Mpc at about half a billion years after the big bang to about 73km/s/Mpc today (the current Hubble parameter value today). When dark energy is taken into account it increases this rate of expansion (over the last several billion years) and so the Hubble parameter is slightly larger today than it would be without dark energy. In the next few tens of billions of years the Hubble parameter will increase exponentially, in one model (where dark energy is the cosmological constant) doubling its rate in another 16 billion years.
Hey Fraser, I want to educate my partner about cosmology and the universe, she is a complete novice. Are there a nice series of videos or resources that would be suitable? She is a very visual learner. Thanks
@@frasercainYesssss, Phil's crash course is SUCH a good proper start. I completely believe that for any person who hasn't had that fire lit within them before, or for those that maybe it's just been a long time for (maybe they loved it as a kid but just lost track of it and never found it again), the astronomy crash course will give them the *best possible chance,* at any age, of having it click for them. I do not believe there is a person better on this Earth for this task than Phil Plait. Crash Course did the world, and astronomy such a service by inviting him to do that series, in that format.
I'll like to add "Astronomycast" to the list. Although it isn't video, it is a fantastic learning resource. I've listened to every episode since I found it about 8 or 9 years ago.
I like the idea of an AR/VR program, or even a plastic cube of our place in the Universe among the other galaxies. But, what would be really cool is a visualization of our galaxy with all the streams of half eaten dwarf galaxies around it. Thanks for the interview, y’all!
Cool Astrophysics at Siena College. I went to school next door at RPI. Fun stuff, great conversation. ??Are the fiber optic cables moved based on a "start (galaxy) chart" before the observation? Like the steel plate version. Do they do any tweaking after some photons are collected?
Hi Fraser I had a question, what is the origin of water let's say in the solar system or any other solar system? What bonds the 2 hydrogen and one oxygen? Thanks for great videos!
QUESTION what if there is a HUGE amount of mass, like a MASSIVE pile of galaxies, all piled up, and they are outside our field of view. And that is why the universe is accelerating. Could that be possible? could it be that mass moves in waves and we are in a lower mass wave moving towards a massive/denser wave of mass that we can't see because of the distance?
The evidence shows that the universe is pretty similar in all directions (isotropic) so to consider a 'wall' of galaxies in all directions that existed before the big bang and somehow survived it goes against all the evidence and theories we have.
