@GeorgeSmyridis If you want to go the physics route and maintain a high level of industrial employability, go experimental materials, condensed matter or optics. Do not be sucked in by the siren song of theory. Even computation is risky though it at least will give you a secondary set of salable skills.
Also do not---under any circumstances---be sucked in by particle- or astro-physics in any form.
Love my particle physics degree. Loved my post-doctoral work. Would probably have made a pretty good industry R&D guy but had a really hard time getting my foot in the door and my colleagues report similar things.
And if you are wondering I ended up professing at a very small state U with no money, equipment, lab space, time off or assistants for research.
@dmckee Are the experimental materials not quite concentrated in certain parts of the world (say, fabs)? And not only that, if you know how to do one experimental technique, sometimes they are (or seem to me) so highly specialized that it can be difficult to switch to something of more interest to industry. I have seen a lot of my friends who had chemistry majors (experimentalists) have problems getting employed. This could of course be country-specific.
@dmckee I disagree. With observatories like LSST coming up soon, in addition to the already-existing set of observatories, data analysis is pretty big in the astro groups (just have to find the right advisor, of course). This would go a long ways to industry jobs in data science
@KyleKanos It should, but it is hard to get a foot in the door. My big contribution to two of my projects was analysis coding. I'm a pretty decent coder with some "big picture" understanding and a lot of experience in distributed cooperative development.
The best programming job I was able to get interviews for payed about what i got as a graduate assistant.
I did eventually find some good advice on tuning my resume for industry and was starting to get nibbles when my current job dropped in my lap.
Big firms almost all have a idiot computer program look at your documents first and they can circular file them if they don't get enough key-word matches.
So you phrase everything in industry terms in hopes that it will actually get to a hiring manager who can bring human intelligence to the job.
@dmckee Well it is always a risk for a company to hire someone who may or may not want to stay long term, so naturally they'd prefer someone who has shown interest (through part-time jobs, internships, whatever), which of course add to the difficulty.
@dmckee True to a certain extent. Often for PhD level jobs you might want to go through a recruiter, though, who will probably get your CV read by the guys actually making hiring decisions. A poorly written CV or a less than excellent fit will get a quick rejection, though.
@dmckee Well I remember dropping my CV to one of those online job sites (not submitting it to any particular job at that time, but making it visible to people hiring), and had recruiters calling me the very next day.
In the end, I did not get my job through a recruiter. I did apply through them to one, and was rejected by the company out right (without invitation to interview) because my background was not mathematical enough for them.
I was quite surprised by the reason, but at least they did have a look.
In an elliptical kepler orbit there is an easy recipe to describe the motion/position of a satellite at time $t$. One just follows the following steps - an important detail for me is that the numerical part has always the same error, the error doesn't increase with time, nor is it based on the ti...
@ChrisWhite some unsolicited (and probably not even that useful) advice: if and when you do make the decision to leave academia, don't waste any time doing so
@dmckee @alarge @ChrisWhite @KyleKanos @ACuriousMind So are there any advantages as far as job prospects are concerned to become a physicist than an engineer? They all get similar jobs anyway :/
I don't know much about Rockets, but all that I have seen, from the Saturn V to SpaceX's Falcon 9 have the engine at the bottom. Doesn't this make the Rocket really unstable, like balancing a pencil on your finger and trying to lift it up? Why do we not pump the exhaust gases up to the top of the...
@ACuriousMind @ChrisWhite @JimsBond Is there any special reason why the Steel Mace is doing crazy amounts of damage? It's 34 (at lvl 1) vs. ~25 for a steel longsword and when I spawned Daedric weapons using the console, they're doing a lot less damage.
@0celo7 The emulator isn't illegal to own. It's illegal to make, but not own. And you can use it legally if it's for mounted games that you actually bought and own
PC games have lots of DLC and bonus content for those that get updates and have legit accounts. They know how to incentivize people to buy the game and make money in the event that people pirate it anyway
Besides, at < $1/h of entertainment, who needs to pirate VGs?
I always used to download the demo versions of games that I couldn't get full on the Sony store for my PSP. That'd leave me drooling for the full version. How less an incentive is that ?
@ACuriousMind It really is already one of my all-time favorite abstracts...
Interesting how he deals with GR...
A very, very different approach from string theory.
String theory assumes spaces as a given, as a medium for vibration; Lisi instead tries to break space itself down into more fundamental parts (is my very early reading).
OK, has everyone now read and digested the 42 pages?... :)
@TerryBollinger Not sure you are comparing the right things here. When I look at the actions he writes down, they seem to reproduce the ordinary SM and gravity actions (which he says explicitly at the end). But it is known that the action for gravity is not quantizable in a renormalizable way, so this paper does not seem to tackle the question of constructing a quantum theory of gravity, while string theory does.
@ACuriousMind I... think I agree with you? I've been looking so far just at the group stuff, not really the GR parts. But yes, it does not take a quantum gravity tact at all, does it?
@JohnRennie for what it's worth, I always figured that as an indicator of someone who shouldn't be asking about time dilation here. Not that I would be opposed to having a canonical Q&A if you want to do it.
@JohnRennie What is the main conceptual issue you'd wish to explain? I have the impression that the issue is not that people can't find explanations of time dilation, it's that they cling to some of their classical (or unphyiscal) preconceptions when interpreting these explanations, and then get horribly confused.
Mentat Masters regularly consume the Juice of Sapho, causing their lips to stain.
According to the Dune Wiki,
Sapho, or more commonly the Juice of Sapho, was a high-energy liquid extracted from the barrier roots of the planet Ecaz. It was used by Mentats who claim that it amplifies the me...
@JohnRennie I'm tempted to talk about a paper I'm writing on what seems to be an overlooked invariant when slicing space time... no, not yet. SR is even cooler and stronger than it might seem from geometry alone.
@DavidZ the diagram was going to start with the Pythagorean expression for ds, then explain that in SR we use the Minkowski metric instead. But I struggle to explain this clearly.
@DavidZ It does feel like roughly the right direction, though I wonder if a bit of creative slicing of the block universe might convey some of the issues too...
Actually I started by trying to write the definitive article on the twin paradox, but realised I needed to explain time dilation to do it. Hence the attempt to write an article on time dilation.
@JohnRennie I dove in deeply to some of the twin paradox descriptions once, and too many of them are sloppy or flat-out wrong. A good description needs to bridge Minkowski and Euclidean, and as you noted that is just not easy to do in a clear, understandable figure.
The point about the twin paradox is that the stay-at-home twin calculates proper time using the Minkowski metric while the travelling twin uses the Rindler metric for all or part of the trip.
But I find myself embarrassingly unable to calculate geodesics in the Rindler metric.
Although I discovered something surprising along the way ...
I've discovered a family of curves in Rindler space that have zero net time dilation. However I struggle to see why this should be so, i.e. what the physical significance of these curves is. My question is can anyone give an intuitive explanation for why these curves have zero net time dilation?
...
@JohnRennie One observation: Any diagram really needs to push hard on the idea of true interchangeability of space and time. I don't think that gets conveyed well enough usually.
Hey, a small observation, tangential: For any isolated system of mass particles, there always exists a "fastest time" frame that includes the center of mass of the system. Yes?
@JohnRennie Pretty much just that: More specifically, if you create a system of particles from a single point in space time, let it expand and get very complicated over time, but eventually require that it all merge back together into a single point again, then the greatest time consumed will always be the particle that never moves away from the start.
Not profound at all, just interesting if you scale it up across larger systems
Pff I just read a topic: "I discovered by look at glibc (gcc libary) that the sine of small numbers is the number itself". - Good job missing a major step in your mathematical education..
oh and this is from a quite well "respected" source even.
@JohnRennie I should finish the thought: For a system of mass point that all originated in a single frame, but has never 're-converged to that frame, do there exist a frame-defined set of mass particles for which elapsed time will always be higher than for any other mass particles?
The answer is of course yes: It will be the set of particles that have remained in the initial inertial frame for the entire time since divergence.
Now while it gets more complicated for something like the Big Bang, the same question can also be applied by scaling upwards to the entire universe.
Which leads to an interesting postulate: Do there exist stars in the universe that have the potential always to demonstrate morealpsed time if you travel to them?
@0celo7 I assume you've just try to call me out on not blocking you. It didn't work. I just assume you say something, hit reply on the most recent post, then change the number to something appropriate. Works every time
According to Maxwell's equations, magnetic fields are divergence-free: $\nabla \cdot \mathbf{B} = 0$. If I understand this correctly, this means that magnetic field lines do not start or end. How can we reconcile this with magnetic reconnection?
We've got something like 5 billion years before that happens, so we'll have plenty of time for terraforming other planets (if not straight-up leaving Sol)
With current technology, a shuttle could make it to Pluto (not that it's a planet...) in around 15 years. I think ion drives (or some other currently theoretical propulsion system) are expected to do it in like 5 years
This is a partial list of Solar System objects by size, arranged in descending order of mean volumetric radius, and subdivided into several size classes. These lists can also be sorted according to an object's mass and, for the largest objects, volume, density and surface gravity, insofar as these values are available. This list contains the Sun, the planets, dwarf planets, many of the larger small Solar System bodies (which includes the asteroids), all named natural satellites, and a number of smaller objects of historical or scientific interest, such as comets and near-Earth objects.
The ordering...
@0celo7 When astronauts return to Earth after a couple months in the ISS, they do so in a stretcher because their muscles are so weak they can't even walk. And that's after strenuous exercise for hours every day.
@JohnRennie I don't know what exposition you plan, but invoking Rindler seems complicated. I've always seen the solution to the twin paradox as exactly the same as the Monty Hall problem: There are really three things (reference frames, classes of door), not just two.
user54412
There is the Earth twin, the outgoing frame, and the ingoing frame. Similarly, there is the revealed door, the selected door, and the unrevealed door. The error people tend to make is to conflate the latter two things in each case.