Thus concludes the tour of some of the unsolved astrophysics problems I found particularly interesting. This entire series touches deeply upon something which Prof. Siana had touched upon in class: astrophysics as the buffet of modern physics. This is a sentiment I have often parroted in my description of astrophysics to others in my pas. As a subject, it is one of the truest blends of all physics applications.
In researching and reviewing these topics, I looked at solutions and mathematics behind each one. All of them are direct applications of topics I have been learning even in my undergrad. They present challenges classical mechanics, quantum mechanics, electricity, magnetism, nuclear physics, programming, and the list goes on. It would take information from all of these fields combined to make a complete analysis of any one of these systems. It is one of the last places where classical mechanics can produce groundbreaking results. One of the last places where observational data is truly valid. One of the last places that one can truly discover something new without having to stare at a microscope for the rest of their
This class was integral in me being re-inspired on astrophysics, and actually this assignment helped a lot. I stared for the last two days at papers and research on some of these topics, and I felt particularly in tune with it all. I might continue with this blog into the future as I read more into the topics (if I ever have time, that is). I kind of like the format that I have come up with, and will be brushing up some of these topics as I read more about them.
Happy holidays,
Aaron
Monday, December 7, 2015
EDUPA: The Flyby anomaly
The Problem:
The flyby anomaly represents an increase in energy due to the passing of spacecraft above the earth. This essentially corresponds to an increase in velocity at the perigee of a spacecrafts orbit where one wouldn't expect it. The fact that this shift occurs means that there is some unexpected added force in the gravitational field of the earth.
The Physics:
This directly relates to orbital mechanics of non-bound objects within earth's orbit. This problem has direct applications to classical mechanics (Keppler's Laws) as well as to electromagnetic principles (perhaps a magnetic field is responsible). From the few increases which have been seen, one group publicised the following equation:
Why does it matter?
As with the corona effect, it appears that we are getting energy from an unknown source, which represents either a gap in our knowledge of earths orbit, or a new step forward in classical mechanics theory. This has potential results in dark matter theory, general relativity, and gravity theory. The monitoring of these effects might provide valuable insight into some of the biggest problems faced by physicists, but offer a chance for us to study it up close.
Who is going to solve it?
There will actually be an Earth flyby this month by the Hayabusa 2, which was launched by the Japan Aerospace Exploration Agency a few years back. They will be closely monitoring the satellite's return, and gathering data on the flyby anomaly. There will not be another flyby until 2018, but the implications of the impact here might be important data in furthering this information.
What I think:I am convinced that we do not know enough about the way gravity works to perfectly account for every celestial effect that we observe: even close to earth. I think that there is clearly some amount of gravity which we are failing to account for during these orbits. Or dark matter halos. But only because I want to believe that one could be accounted for and observed so close to earth.
The flyby anomaly represents an increase in energy due to the passing of spacecraft above the earth. This essentially corresponds to an increase in velocity at the perigee of a spacecrafts orbit where one wouldn't expect it. The fact that this shift occurs means that there is some unexpected added force in the gravitational field of the earth.
The Physics:
This directly relates to orbital mechanics of non-bound objects within earth's orbit. This problem has direct applications to classical mechanics (Keppler's Laws) as well as to electromagnetic principles (perhaps a magnetic field is responsible). From the few increases which have been seen, one group publicised the following equation:
which corresponds to the observed shift in gravity as we have collected existing data.
Why does it matter?
As with the corona effect, it appears that we are getting energy from an unknown source, which represents either a gap in our knowledge of earths orbit, or a new step forward in classical mechanics theory. This has potential results in dark matter theory, general relativity, and gravity theory. The monitoring of these effects might provide valuable insight into some of the biggest problems faced by physicists, but offer a chance for us to study it up close.
Who is going to solve it?
There will actually be an Earth flyby this month by the Hayabusa 2, which was launched by the Japan Aerospace Exploration Agency a few years back. They will be closely monitoring the satellite's return, and gathering data on the flyby anomaly. There will not be another flyby until 2018, but the implications of the impact here might be important data in furthering this information.
What I think:I am convinced that we do not know enough about the way gravity works to perfectly account for every celestial effect that we observe: even close to earth. I think that there is clearly some amount of gravity which we are failing to account for during these orbits. Or dark matter halos. But only because I want to believe that one could be accounted for and observed so close to earth.
EDUPA: Astrophysical Jets
The Problem:
This particular unsolved problem in peculiar happenings of post-collapsed stars. Often associated with quasars and radio galaxies, these objects defy what we know about the final stages of a star's life. Essentially they are large "jets" of various plasma-state matter (I say matter here because there is still debate as to what is actually emitted) which will escape from the source at near the speed of light; these will carry large amounts of energy, but the physics behind them remains largely a mystery.
The Physics:
The physics in question here has a lot with the collapsing of late aged stars. In a similar manner to how we may not model late life stars, we are unable to effectively determine what would cause these streams to appear. The prevailing theories relate to the energy caused by the rotation of superdense objects in space, which may have an intrinsic magnetic field or angular momentum. There are currently no equations dictating the behavior of these objects, but we have a picture of them, and can explain that they could exist.
Why does it matter?The ability to model this could have implications towards special relativity, matter and star composition, and of course orbital mechanics. This may also provide solutions to some of the other problems currently facing astrophysicists such as Gamma-Ray Bursts. It would also lead potentially to an insight into black holes.
Who is going to solve it?
There are currently many teams working on this problem from many different schools. Upon a quick search I found that there were papers publishing analyses recently. Most recently I found an article from an international team headed by an Italian observatory on a large gamma wave outflow from some deep point of the galaxy.
What I think:
The release point from a super dense object at some very close distance becomes enough to make the objects act in opposition to the force of gravity. Essentially, when you take the electroweak forces and collapse them to a singularity, there is an explosion of sub-sub-atomic particles. This causes the particles to break down to a further state, be able to escape the immense gravity caused by such a dense object, and reform on their way out of the object. The quantum mechanical principles on which these particles act might work to dictate the polar nature of these jets. The recombination principle could explain both their relativistic nature and their obscured nature. The polarity might also be explained by which particles combine to allow for escape speeds. There might also be other things escaping, but by reforming they take on a mass which cannot escape a black hole's gravity.
EDUPA: Coronal Heating
This one might actually break some laws of physics. The coronal heating problem refers to the unusual phenomenon viewed around our sun. Essentially, the corona of the sun (the area immediately surrounding the surface) is much hotter than the surface itself. Flying in the face of logic and thermodynamic equilibrium, it is energy where energy shouldn't be.
The Physics:
First and foremost thermodynamics. The second law of thermodynamics implies that heat energy should appear as a continuous gradient, and that energy must appear as a function of entropy. Should the heat here be greater than the source that is generating it, then there may be some issues in the way which we are currently viewing the energy. Or perhaps the way that the energy is being generated. The solution to this problem lies in the fields, forces, and processes of the sun's fusion. Perhaps a solution would appear with more careful analysis of the energy production of our sun. Theoretical solutions range from magnetic field incongruities to wave-photosphere interactions.
Why does it matter?
One of a few things might come out of this. One, the discovery of a new physical process by which energy transportation might occur in stellar bodies. Two, a break in what was once viewed as a classically fundamental law by a non-fundamental process: making that law have to change. Three, a discovery of some error in the measurements of the heat of a star: leading to better methods of measurement or improvements in equipment. Basically, we are either wrong about physics, wrong about engineering, or lacking in knowledge of how stars work. The solution to any of these would be greatly beneficial.
Who is going to solve it?
Nasa is sending a solar probe to make measurements on the sun sometime in 2018. They plan to use the data taken from this mission to better understand the corona of the sun, as well as the origin of solar winds and various other processes.
What I think:
The effect might be an illusion in the way that we view the surface of the sun. There might be particles excited by the energy emitted by the sun which react to produce their own energy. Perhaps the corona is composed of molecules held there in a sort of "atmospheric" effect. Or, again: Aliens.
Sources:
EDUPA: Space Noises
The Problem:
Unlike my last post on the three body problem, this will deal more with two particular mysteries rather than a more general case of astrophysics problems. This post will focus on the well-known "WOW!" signal and the lesser known "Space Roar" signal.
The story of the "WOW!" signal is fairly well known. In 1977 the Big Ear radio telescope picked up a particularly strong radio signal coming from a point of deep space that seemed to contain no terrestrial bodies. It was large enough to be ruled out of any particular error or human interaction, and almost all theories of foul play have been ruled out. It is essentially a signal that came from a completely unknown source, and people have tried for a while to find it again.
The more recent and more obscure "Space Roar" signal was presented in 2009. Essentially, it came out as a loud, low frequency noise that appeared about six times the normal background noise coming from a similar patch of sky. Again, it is an unexplained radio signal coming from space which appears to unexplained.
The Physics:
Since noise can't travel through space, astrophysicists will often search for peculiarities in the electromagnetic signals that can travel great distances to our planet. This is the same method through which we might find variances in gravity, shifts in creation of stars, and much more. The Big Ear "telescope" did just that. During its six years of active operation, it spun as the earth did in order to gather data from various points of space. it was essentially one way to map out the universe. This same method may be used to pick up on radio wavelengths of things which fail to emit visible light, as well: looking at high energy sources such as pulsars or quasars.
Why does it matter?
Aliens (Maybe). Many theorists (and some non-theorists) have suggested that the WOW signal is evidence of extraterrestrial beings. This, of course, is impossible to prove or disprove; however there are equally as many other astronomical events which might produce a similar signal. Even though scientists have passed over the spot many times with similar equipment as a direct result of finding the signal, they have found no evidence of a repeated signal.
The Space Roar signal could have more interesting applications, however. The effect of the radiation from a space like this could be useful in the description of some of the universes earliest stars. This may obscure scientists ability to detect radiation from remnants of first generation stars.
Who is going to solve it?
The WOW signal has long since passed, and the source of the signal might very well not be where it was when we saw it. On top of that, the Big Ear telescope has been dismantled since the mid seventies so we can not repeat the experiment itself. Although on searching this I did find many forums dedicated to tearing apart the details in order to find extraterrestrial life, so there is always that.
The Space Roar puzzle might be something more pertinent to modern astrophysics however. The fact that this signal was much stronger than anything previously expected, but it is a repeatable measurement actually indicates that there are fundamental truths at play here. As such, a team at JPL is currently tackling the problem, but no new results have been published since 2010 from the main team.
What I think:
There are proponents who mumble something about dark energy on every comment section as I looked through this problem, but I wouldn't know much about that. I say that there is solid evidence that both can be summed up as the remnant energy of a cosmic event that we are incapable of detecting.
Sources:
http://www.nasa.gov/centers/goddard/news/topstory/2009/arcade_balloon.html
http://www.space.com/6293-mystery-roar-faraway-space-detected.html
http://www.astronomytoday.com/astronomy/radioastro.html
Unlike my last post on the three body problem, this will deal more with two particular mysteries rather than a more general case of astrophysics problems. This post will focus on the well-known "WOW!" signal and the lesser known "Space Roar" signal.
The story of the "WOW!" signal is fairly well known. In 1977 the Big Ear radio telescope picked up a particularly strong radio signal coming from a point of deep space that seemed to contain no terrestrial bodies. It was large enough to be ruled out of any particular error or human interaction, and almost all theories of foul play have been ruled out. It is essentially a signal that came from a completely unknown source, and people have tried for a while to find it again.
The more recent and more obscure "Space Roar" signal was presented in 2009. Essentially, it came out as a loud, low frequency noise that appeared about six times the normal background noise coming from a similar patch of sky. Again, it is an unexplained radio signal coming from space which appears to unexplained.
The Physics:
Since noise can't travel through space, astrophysicists will often search for peculiarities in the electromagnetic signals that can travel great distances to our planet. This is the same method through which we might find variances in gravity, shifts in creation of stars, and much more. The Big Ear "telescope" did just that. During its six years of active operation, it spun as the earth did in order to gather data from various points of space. it was essentially one way to map out the universe. This same method may be used to pick up on radio wavelengths of things which fail to emit visible light, as well: looking at high energy sources such as pulsars or quasars.
Why does it matter?
Aliens (Maybe). Many theorists (and some non-theorists) have suggested that the WOW signal is evidence of extraterrestrial beings. This, of course, is impossible to prove or disprove; however there are equally as many other astronomical events which might produce a similar signal. Even though scientists have passed over the spot many times with similar equipment as a direct result of finding the signal, they have found no evidence of a repeated signal.
The Space Roar signal could have more interesting applications, however. The effect of the radiation from a space like this could be useful in the description of some of the universes earliest stars. This may obscure scientists ability to detect radiation from remnants of first generation stars.
Who is going to solve it?
The WOW signal has long since passed, and the source of the signal might very well not be where it was when we saw it. On top of that, the Big Ear telescope has been dismantled since the mid seventies so we can not repeat the experiment itself. Although on searching this I did find many forums dedicated to tearing apart the details in order to find extraterrestrial life, so there is always that.
The Space Roar puzzle might be something more pertinent to modern astrophysics however. The fact that this signal was much stronger than anything previously expected, but it is a repeatable measurement actually indicates that there are fundamental truths at play here. As such, a team at JPL is currently tackling the problem, but no new results have been published since 2010 from the main team.
What I think:
There are proponents who mumble something about dark energy on every comment section as I looked through this problem, but I wouldn't know much about that. I say that there is solid evidence that both can be summed up as the remnant energy of a cosmic event that we are incapable of detecting.
Sources:
http://www.nasa.gov/centers/goddard/news/topstory/2009/arcade_balloon.html
http://www.space.com/6293-mystery-roar-faraway-space-detected.html
http://www.astronomytoday.com/astronomy/radioastro.html
EDUPA: The Three Body Problem
The Problem:
The first topic of the evening I will talk about is the well-known three body problem. More an interesting case in classical mechanics than necessarily one of astrophysics-exclusive applications: this problem refers to the complete solution of motion three objects which both emit and impart a force upon one another. The classic example of this is three bodies in space, each with a certain mass and gravitational field.
The physics:
This problem primarily revolves around Newton's second equation, F=ma, and the universal law of gravitation (F=G*M_1*M_2/R^2). The most important part here, of course, is the R^2 dependency of this interaction. Since we are looking at three bodies, each body will have a constantly changing and updating radius in relation to the others. This is a problem, as any time the relationship between them changes, the force changes direction and strength. Essentially, updating the radius term for any of these bodies would change the effect felt by both the other bodies. Even if the simulation does a good job of modeling and averaging the steps taken by these, the finite nature of these steps as done by a computer would mean that they must still happen sequentially. This compounds any error, and leads to an inaccurate measurement.
Why does it matter?
The modeling of this will help astrophysicists to better understand the way that planets move, allowing them to solve many more complicated systems than we currently are able to. The solution to this has applications in computing and numerical analysis as well. By devising a way to make a true integration of the motion, one would also find a way to make computations that can occur simultaneously and without error. Assuming a solution to the three body problem would extrapolate to n-body problems, it could have applications to fields such as biology, chemistry, and materials science to explain molecular interactions as well.
Who is going to solve it?
From what I have found, there are no major publications of people actively working on this problem. It seems to be something more of a mathematical anomaly than an area of active physics. There are many programmers probably working on similar methods, but I couldn't find recent works on the subject.
What I think:
The non-linear nature of this problem seems like something that functional programming could potentially solve. By passing terms that are not by nature finite, it could be one way to resolve the dependency issues inherent to the problem. Time to start studying my lambda calculus!
EDUPA: Introduction
Welcome to "An evening of discussion on unsolved problems in Astrophysics". Unfortunately, despite starting research for these blogs almost twenty four hours ago (where it would have been a day rather than an evening, but names can be changed), I ended up down a rabbit hole of some really interesting topics. In these posts, I will attempt to present the problem, the physics behind the problem, why it is important, what current research (if any) is being made to solve it, and then present my best educated guess for a solution. I am not going to attempt to solve any of these (clearly), but I think it is an interesting discussion to look at some of the hardest problems facing modern astrophysicists.
Sunday, November 29, 2015
Sooo Hot!
In September of this year, the galaxy's hottest white dwarf was discovered by astronomers from the universities of Potsdam and Tübingen. This came from analysis of spectra analyzing the edge of the Milky Way, in which they discovered a relatively small, but very hot star in its cooling phase. This star (RX J0439.8-6809) was measured to be around 250,000K, although it is estimated that at its peak the temperature was around 400,000K. A star of such low density and such high temperature is indicative of something originating very far from us; indeed, this was found to be a part of a larger gas cloud moving towards the Magellenic cloud structure. Not much is known about the formation of this unusual star beyond that.
Thursday, November 5, 2015
Space Elevator Part 2: Elevation time, come on!
Reach for the stars! No, really, reach! They are right there above you!
As mentioned in part one of this blog post, lifting yourself up off of the ground will require a lot of energy, as part of whatever system one tries to lift will be redundant weight of fuel, which of course may only last so long. The thought arises that there must be another way. Looking simply at Newton's third law, there are more ways to dissipate lifting energy than through the air. Rather than having fuel provide thrust up into the atmosphere, why not push off of the ground to launch something into orbit.
There are many ways of doing this: from cables on satellites to towers, using already in place physical systems could be an ideal way of lifting something out of the atmosphere. So, what are our options here?
First, let's look at a cable, as it is one of the simpler examples. In order to escape the atmosphere, an object should be able to travel about 50km into the air. In
As mentioned in part one of this blog post, lifting yourself up off of the ground will require a lot of energy, as part of whatever system one tries to lift will be redundant weight of fuel, which of course may only last so long. The thought arises that there must be another way. Looking simply at Newton's third law, there are more ways to dissipate lifting energy than through the air. Rather than having fuel provide thrust up into the atmosphere, why not push off of the ground to launch something into orbit.
There are many ways of doing this: from cables on satellites to towers, using already in place physical systems could be an ideal way of lifting something out of the atmosphere. So, what are our options here?
First, let's look at a cable, as it is one of the simpler examples. In order to escape the atmosphere, an object should be able to travel about 50km into the air. In
Tuesday, November 3, 2015
Space Elevator Part 1: Burn Baby Burn
One of the largest hurdles in any technological advancement is the provision of power. As new technology comes out, it must overcome the transport and size of power. Space travel is no exception to this dilemma. Any self-propelled vessel must contain something internal to provide force. The success of any space program has hinged upon the ability to make the power-to-weight ratio as large as possible. If this ratio may be limited, then the ship will have an easier time lifting itself from earth's orbit.
Let's look at a simple example:
A ship weighs 50000 kg, and carries 500 kg of gasoline.
Burning gasoline provides about 50Mj/kg, so burning all of this fuel will provide about 25,000 Mega-Joules of energy.
Now, since we cannot burn all of this at once (lest one wishes to explode), so lets burn all of this over a rate of about a minute. So now we get a rate around 500MJ every second. This still sounds like a lot of energy!
But the force of gravity alone on our rocket ship is about 500000 Newtons. This means simply to negate our gravity , it would take about 500000 Joules, or about .5 MJ. This is not very much at all! We have 1000 of those! But force is an acceleration, so it takes more than that to overcome inertia. Lifting this machine will take much more than the amount of prescribed gasoline.
Just doing some approximations, we can expend about 45MJ a second towards lifting the craft up and out of the atmosphere. which thus would exert about
Gas is really heavy, so people have used plenty of alternative fuel sources, and compressed forms of certain elements burn with incredible energy and can do all of the heavy lifting, but they overlook something else entirely: why must the world burn?
That method of chemical energy transmission means carrying your own fuel source, which can be impractical. People have proposed many mechanical solutions, such as catapults and slingshots, but one theoretical marvel stands out in my imagination: the space elevator.
The basic premise of this apparatus would be an object that had one mechanical point in space, and one which reached to the ground. This seems simple enough, but the feat of engineering which comes with it would involve some intensive structural and materials engineering. All of which will be looked at in the riveting part two of this blog post!
Let's look at a simple example:
A ship weighs 50000 kg, and carries 500 kg of gasoline.
Burning gasoline provides about 50Mj/kg, so burning all of this fuel will provide about 25,000 Mega-Joules of energy.
Now, since we cannot burn all of this at once (lest one wishes to explode), so lets burn all of this over a rate of about a minute. So now we get a rate around 500MJ every second. This still sounds like a lot of energy!
But the force of gravity alone on our rocket ship is about 500000 Newtons. This means simply to negate our gravity , it would take about 500000 Joules, or about .5 MJ. This is not very much at all! We have 1000 of those! But force is an acceleration, so it takes more than that to overcome inertia. Lifting this machine will take much more than the amount of prescribed gasoline.
Just doing some approximations, we can expend about 45MJ a second towards lifting the craft up and out of the atmosphere. which thus would exert about
Gas is really heavy, so people have used plenty of alternative fuel sources, and compressed forms of certain elements burn with incredible energy and can do all of the heavy lifting, but they overlook something else entirely: why must the world burn?
That method of chemical energy transmission means carrying your own fuel source, which can be impractical. People have proposed many mechanical solutions, such as catapults and slingshots, but one theoretical marvel stands out in my imagination: the space elevator.
The basic premise of this apparatus would be an object that had one mechanical point in space, and one which reached to the ground. This seems simple enough, but the feat of engineering which comes with it would involve some intensive structural and materials engineering. All of which will be looked at in the riveting part two of this blog post!
Monday, October 5, 2015
Week 1: Galaxy Density
Today during class, I mistakenly heard Prof. Siana make a comment that the Milky Way was a particularly dense galaxy. Although I misheard (he said that galaxies, in general are dense compared to space), this prompted me to ask him afterward about the measurement of galaxy density. The methods he described to me, in a quick recap, involved using the make-up of stars in the galaxy (by percent of different stars in the galaxy) and the luminosity of the galaxy. From that, astronomers can extrapolate how roughly how many massive stars are in the galaxy. Then, using the size (as determined by parallax measurments), they can determine the density of the galaxy.
There are some major innacuracies in this, of course; some objects in the galaxy are contributing to the overall mass of the galaxy, but are not inherently luminous. The largest of these, it seems, would be dark matter clusters. This can be slightly corrected by gravitational lensing. In my research for this blog, I came across an article from 2013: a paper highlighting techniques used by astronomers at numerous research institutions collaborating to measure data on the density of dark matter distribution among multiple galaxies.What they saw lined up well with current CDM, or cold dark matter, theories.
The methods, which are more comprehensively discussed in the linked article, seem to present improved ways on accounting for the density of dark matter when dealing with galaxy density.
Here is a link to the academic article, and a link to the article that led me to it. Hope everyone is having a good start to school, and good luck on the assignment.
-Aaron
P.S. Just a random occurrence. As I was re-doing problem four tonight (on Comet Lovejoy), I was shuffling through old music, when a song by the same name started playing. I thought it was a weird coincidence. I have it linked here, for any of you who would appreciate random jazz/hip hop instrumentals. I don't think it has anything to do with the comet itself, but it is still a good song. The whole album is pretty good, actually, if you are interested.
There are some major innacuracies in this, of course; some objects in the galaxy are contributing to the overall mass of the galaxy, but are not inherently luminous. The largest of these, it seems, would be dark matter clusters. This can be slightly corrected by gravitational lensing. In my research for this blog, I came across an article from 2013: a paper highlighting techniques used by astronomers at numerous research institutions collaborating to measure data on the density of dark matter distribution among multiple galaxies.What they saw lined up well with current CDM, or cold dark matter, theories.
The methods, which are more comprehensively discussed in the linked article, seem to present improved ways on accounting for the density of dark matter when dealing with galaxy density.
Here is a link to the academic article, and a link to the article that led me to it. Hope everyone is having a good start to school, and good luck on the assignment.
-Aaron
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