Ask HN: Is physics moving forward? • Hacker News Board

Re: Ask HN: Is physics moving forward?

#51

Post by nvader » Fri, Jul 17, 2015, 6:15 PM UTC

mdup wrote: post #45

pwnna wrote: post #40

Earlier quoted context omitted.

Do you think there's a limit on how much we can understand in physics/any field? My reasoning on this is that since everyone has a finite lifespan, understanding/work will be lost as the researcher retire, move to a different field, or die, unless this information is transmitted to someone else during their life time. However, as we understand more, we have to teach people more. This brings in two problems that I see…

The point of your comment is disproved by your last paragraph! The more science is discovered, the more it gets compacted into the essentials of this knowledge. If 100 year old PhD level fluid dynamics can be taught to undergrads, this means it got digested into the most useful part of the work. Similarly, it's considered basic undergrad work to understand Fourier decomposition; but the notations and clarity we get t…

Not to mention that lifespans get longer!

Re: Ask HN: Is physics moving forward?

#52

Post by rn222 » Fri, Jul 17, 2015, 6:24 PM UTC

sqrt17 wrote: post #47

ISL wrote: post #13

As someone who's been in physics for much of the last twenty years, I'd guess that things are going at about the same rate. I don't think that the rate is "crawling", though. If you look on log plots of parametrized experimental progress, progress remains linear, so it's a Moore's law like improvement on many fronts. The emergence of precision cosmology has really transformed astrophysics in the last twenty years. Th…

What are the assumptions behind "log plots of parametrized experimental progress"? What do these mean in the real world? To give an example of why "pouring money into it and getting slower and slower progress" could translate into linear progress on a log plot, imagine you have to pour in x² amount of (money, people, time) to get to level x of progress. In that case "we go slow" means, "we'll gobble up larger and lar…

Add that to the fact there is no global dependency tree of "What we need to discover to make this practical technology possible", how can we be sure that existing/future research funds are focused in the areas needed to make the most valuable technologies available?

Re: Ask HN: Is physics moving forward?

#53

Post by twerkmonsta » Fri, Jul 17, 2015, 6:45 PM UTC

pwnna wrote: post #40

stared wrote: post #6

As a PhD in physics - progress in pure physics is slowing down (or at least progress per scientist). The delay between a discovery in physics and a Nobel prize is getting bigger and bigger [1]. It's true for all fields, but the effect is particularly strong for physics. '''It is safe to say that late 1920s and early 1930s were the “Golden Age” of 20th century physics, when the progress was lightning-fast and new disc…

Do you think there's a limit on how much we can understand in physics/any field? My reasoning on this is that since everyone has a finite lifespan, understanding/work will be lost as the researcher retire, move to a different field, or die, unless this information is transmitted to someone else during their life time. However, as we understand more, we have to teach people more. This brings in two problems that I see…

I'm not physics expert, but I think there may be a limit to what we can understand about the physical world. Especially when we get down to such small scales. However, I don't think this is because of limited lifespans.

I've heard it said that string theory could never be scientifically tested in a traditional sense. People sometimes compare it to a religious philosophy because of this quality of untestability.

Maybe the logic of the universe at the lowest levels are hidden from us. If the universe is a computer simulation then we almost certainly are not exposed to the underlying mechanisms of how it works at the lowest level.

The fluid in a fluid simulation doesn't have access to the knowledge of how the computer on which it is running functions. The fluid is just information. That information is manipulated by the running program, but the code of the simulation is not built into the information representing the fluid.

Maybe the matter in our universe exists in the same way, as information. Maybe the mechanics that drive the motion of the smallest particles are not exposed.

I'm sure I'm not the only person to postulate on this. People have probably written very scientific papers on this very topic. I honestly don't know, but it's what my programmer brain leads me to believe.

Re: Ask HN: Is physics moving forward?

#54

Post by pwnna » Fri, Jul 17, 2015, 6:49 PM UTC

mdup wrote: post #45

pwnna wrote: post #40

Earlier quoted context omitted.

Do you think there's a limit on how much we can understand in physics/any field? My reasoning on this is that since everyone has a finite lifespan, understanding/work will be lost as the researcher retire, move to a different field, or die, unless this information is transmitted to someone else during their life time. However, as we understand more, we have to teach people more. This brings in two problems that I see…

The point of your comment is disproved by your last paragraph! The more science is discovered, the more it gets compacted into the essentials of this knowledge. If 100 year old PhD level fluid dynamics can be taught to undergrads, this means it got digested into the most useful part of the work. Similarly, it's considered basic undergrad work to understand Fourier decomposition; but the notations and clarity we get t…

My worry is that as we split knowledge out, no one will understand the big picture as they're always focused on their specialty of their specialty.

Since we are teaching people less in depth stuff as they need to go very far into science, it seems like building knowledge with unstable foundation. The lack of branching out may also inhibit discovering certain connections between fields that may proved to be enlightening.

Re: Ask HN: Is physics moving forward?

#55

Post by FiatLuxDave » Fri, Jul 17, 2015, 6:59 PM UTC

As a physicist for the last 20 years, I suppose I am to partly to blame... ;)

I would say that it depends on what you call physics. The areas of physics that were symbolic of advancement in the previous 20 years will not necessarily be the same areas where advances will be in the next 20 years. During the 1800s, advances in physics in the first half of the century lead to technological advances in steam power and electricity in the second half. If you thought of physics as meaning electromagnetism and thermodynamics, you might think that there were few advances in physics in the first half of the 20th century. And there were people that felt that way! But I think that nowadays we would think that Einstein's heyday was an era of major physics advances. So, maybe you shouldn't look at those areas that are reaching the plateau of their sigmoid curve, but newer areas.

Classic particle physics, exemplified by the likes of Chadwick and Lawrence way back in the 1930s, leading to the explosion of the particle zoo in the 1950s, and then the diminishing returns of the LHC era, would be a good example of sigmoid curve development in Physics. If physics only means this stuff to you, then yes, it is going slower than it was.

Areas of physics that have been closer to the high slope region of their development in the last 20 years:

Quantum Information Theory (as noted by @abdullahkhalids)

Dark Matter/Energy/whatevertheheckitis

Medical Physics (from lead block linacs and xrays to IMRT/VMAT & modern imaging)

Materials Science/'Condensed Matter' physics

Black Hole science, esp. thermodynamics

Gravity waves, or the lack thereof (interesting either way)

techniques for signal/data processing and analysis (such as superresolution or single detector imaging)

I'm sure there's more that I'm not aware of. Anything that is really very new is too small to get much press right now. Pretty much by definition, the new small stuff won't have the big press budget of CERN or NASA.

Re: Ask HN: Is physics moving forward?

#56

Post by sampo » Fri, Jul 17, 2015, 7:11 PM UTC

pwnna wrote: post #40

stared wrote: post #6

As a PhD in physics - progress in pure physics is slowing down (or at least progress per scientist). The delay between a discovery in physics and a Nobel prize is getting bigger and bigger [1]. It's true for all fields, but the effect is particularly strong for physics. '''It is safe to say that late 1920s and early 1930s were the “Golden Age” of 20th century physics, when the progress was lightning-fast and new disc…

Do you think there's a limit on how much we can understand in physics/any field? My reasoning on this is that since everyone has a finite lifespan, understanding/work will be lost as the researcher retire, move to a different field, or die, unless this information is transmitted to someone else during their life time. However, as we understand more, we have to teach people more. This brings in two problems that I see…

> It takes longer for people to learn up to the frontier of science

(1) It takes much less time to teach something, than was spent to figure things out the first time.

(2) When teaching improves, the essential points of a topic can be taught in less time, then what was spent when the topic was new. Then a topic is new, usually it is first taught following the lines and chronology on how it was discovered. Later improved teaching can figure out ways to get free of the chronology of the original story, and just teach the plain fact.

While Darwin's finches are still sometimes mentioned when teaching evolution, the whole story of measuring all kinds of properties of those birds in different islands, and presenting this data, and what can we deduct from it, is rarely presented. We just jump to the main point: species adapt and evolve.

Arguable, teaching physics still almost everyplace follows the historical chronology: mechanics, electromagnetism, quantum mechanics, which usually pushes quantum mechanics to the 3rd year in a university. The mathematical machinery of quantum mechanics however shouldn't take two full years to master, so maybe there could be a route to proceed quantum mechanics faster, not trying to cover all of classical physics first.

(3) I assume the success of future researchers is party build upon that they had access to good teachers, or good textbooks, which made it possible for them to quickly absorb the present state of knowledge. But there are voices complaining that producing good teaching material is not incentivized in the present academic system.

Re: Ask HN: Is physics moving forward?

#57

Post by johncolanduoni » Fri, Jul 17, 2015, 7:17 PM UTC

String theory often gets ragged on for not having any direct practical applications, which is certainly true. However, some of the mathematics developed by string theory is key in theoretical work in fields where theory and experiment have a much tighter bond. For example, topological quantum field theory[1] has found widespread important applications in quantum information, and it was pioneered by none other than Witten himself. This isn't just on the theory side; experimentalists are looking at topological states of matter for a variety of applications, including quantum computing.

[1]: https://en.wikipedia.org/wiki/Topological_quantum_field_theo...

Re: Ask HN: Is physics moving forward?

#58

Post by johncolanduoni » Fri, Jul 17, 2015, 7:21 PM UTC

jammycakes wrote: post #38

It seems to me that ground-breaking discoveries in physics are generally getting more expensive. Up till about the early 20th century, ground breaking physics was largely "two guys in a garage" territory -- single individuals such as Newton or Cavendish tinkering in their own private laboratories using fairly modest equipment. Teenagers replicate their experiments in school physics lessons with equipment costing no m…

Most physics isn't done with space telescopes or particle accelerators; and very few groups require billions of dollars of equipment (considering the NSF budget is less than 10 billion dollars, there wouldn't be much to go around). Theoretical physics in experimentally relevant fields is about as cheap as its ever been; you really only need professors, a building, whiteboards, and travel funds.

And believe me, there are a lot of experimental physicists doing excellent work with two guys in a garage levels of equipment.

Re: Ask HN: Is physics moving forward?

#59

Post by CountSessine » Fri, Jul 17, 2015, 7:23 PM UTC

rn222 wrote: post #52

sqrt17 wrote: post #47

Earlier quoted context omitted.

What are the assumptions behind "log plots of parametrized experimental progress"? What do these mean in the real world? To give an example of why "pouring money into it and getting slower and slower progress" could translate into linear progress on a log plot, imagine you have to pour in x² amount of (money, people, time) to get to level x of progress. In that case "we go slow" means, "we'll gobble up larger and lar…

Add that to the fact there is no global dependency tree of "What we need to discover to make this practical technology possible", how can we be sure that existing/future research funds are focused in the areas needed to make the most valuable technologies available?

Is that why we're doing physics research? Practical technology?

Re: Ask HN: Is physics moving forward?

#60

Post by hellameta » Fri, Jul 17, 2015, 7:34 PM UTC

btilly wrote: post #41

hellameta wrote: post #27

Earlier quoted context omitted.

I agree with you but not with respect to Physics. I believe it is very likely that in 100 years we will think "Can you believe they didn't understand X" in things like psychology and all of the new emerging cross disciplinary fields that have emerged from it. Economics is a good example as well I believe... Up until the second half of the 20th century many economists were not basing their theories on data but rather…

Your belief about economics indicates that you are part of a minority paradigm that has produced interesting data but not managed to transform economics yet. If it does succeed, then your hope for it will be perfectly justified. But most such movements do not succeed. The problem is that success has to be so compelling that people who are working within different paradigms (economics have many) generally figure out t…

I think that my original comment wasn't specific enough and that we are in agreement. I do see it as a 'low order correction' but one that will (and has already) added a lot to the field.

Richard Thaler puts it much better than me when he roughly says that the best economics work in the last decade is by classic economists doing good empirical work. Which, at least in my understanding, is the real 'gift' of the 'behavioral' approach.