I was talking to my roommate last night while watching a physics documentary and he lamented that no groundbreaking discoveries have been made in physics in his lifetime (he is 21). I am not sure if this is true or not because in the last 25ish years we have discovered quantum computers and various subatomic particles (quarks, leptons, neutrinos). However some of these are closer to 40 years old, but they still strike me as big discoveries. Not necessarily groundbreaking, but pretty important.
Have major developments (on the scale of the discovery of QM, or the discovery of relativity) been done in the last 25 years in physics?
String theory has been big… though much like ToR it won’t be vetted for a LONG time… (not sure which theory to follow yet)… finding new subatomic particles is about as big as you get… so not sure why they dont qualify…
We have been able to measure things to levels before unknown… explore the universe and its happenings in ways never before possible… develop better methods of… well just about everything…
We have more or less proven the existance of black holes… measured effects of quatum mechanics…
What exactly would qualify as ground breaking?
Physics is a very specialized world these days… there are LOTS of ‘ground breaking’ work done… but unless you are in a field to use it, you might not hear about it/understand it’s impact…
HECK… solid state devices have come so far using new phyiscal understandings, that you computer has more power than any mainframe made in the early 80’s…
Not in physics. But I think the discovery of extra-solar planets is pretty big. Not so long ago, planets outside our solar system was just speculation.
It depends on your standard of “major breakthrough”. We haven’t had anything on the order of the discovery of quantum mechanics or general relativity since, well, the discovery of quantum mechanics and of general relativity. Or at least, we don’t think so. String theory, if it works, would qualify, but we may never know if string theory works: All of the obvious tests are so far out of our reach that we can’t even conceive of our descendants performing them. It may be that there are some easier, non-obvious tests, but as is the nature of non-obvious things, we don’t know yet what they are, or even if they exist.
But breakthroughs of that magnitude are rare, and frankly, we’re doing well to have made two of them in the past century. The last one before that would probably be Maxwell’s equations of electromagentism, and before that we’re looking at Newton. If you’ll settle for something smaller, there have been plenty of recent breakthroughs. For instance, it’s only in the past few years that we’ve discovered neutrino oscillation (it was hypothesized before, but it’s only now that we have the evidence).
And if you count cosmology as physics, we’ve made leaps and bounds there in the past 3-5 years. When I started grad school, if you asked how old the Universe is, we’d have said 10-30 billion years. Now, we can confidently put the age at 13.7 billion years, to within about 1%. And we’ve made multiple independant measurements of the composition of the Universe, and discovered that not only does some form of dark energy exist, but that it’s 70% of the “stuff” in the Universe.
Well, it may be true that physics has entered more of an evolutionary, as opposed to revolutionary, phase of development. Still, I will add to the list of important, if not completely revolutionary developments the following:
(1) The understanding of the importance of collective phenomena. Roughly speaking, this is the idea that important new physics arises when you put a whole bunch of particles together and thus working out the properties of the constituent particles is not really very far along the way of explaining most real-world phenomena. This is a big tent under which you could incorporate such things as the fractional quantum hall effect, the new high-Tc superconductors, etc. This idea was perhaps best, and most aggressively, spelled out by Bob Laughlin in a talk at the 1999 Centennial Meeting of the American Physical Society. Laughlin had just won the Nobel Prize in the past year for his theory explaining the fractional quantum hall effect and had seen a talk by one of the high-energy theorists (Steven Weinberg?) who couldn’t resist snidely saying that the really fundamental, important questions in physics were in high-energy physics. Laughlin, who if he wasn’t a physicist would probably be a streetfighter, put up a slide that was titled, “Things that the final Theory of Everything will not explain”. The first 4 things on the list were earth, air, fire, water…after which it got into more random things like “hippos” and “chocolate”. Laughlin concluded his talk by saying something like, “So, as we approach the end of the 20th century, reductionism is finally dead.”
(2) Related closely to the above point, I think the rise in computer power has finally made it possible to realistically study some real-life complex materials that were essentially out of the bounds of possibility before. It has also allowed physicists to expand their reach and apply their approaches to subjects traditionally outside of physics, such as traffic flow, the stock market, and lots of biologically-inspired issues. In fact, some have argued that physicists ought to redefine themselves not so much by what they study as by their approach and the techniques that they use. (Some would argue that this idea is coming from the fact that the really big stuff in what was traditionally been considered physics has been done and that this will be the century of biology…or whatever.)
(3) This is sort of on the border of physics and mathematics…but I would argue that chaos, i.e., sensitivity to initial conditions, has been a very important concept because it brings up the inherent limitations of predictability of many systems.
Oh yeah…another thing you could put in the list of major feats in physics is the imaging and even fabrication and design of materials on the atomic scale…for example, the scanning tunneling microscope and lots of stuff in the field of nanotechnology.
Unfortunately, and for the time being, most physics advances are more or less… useless. Not that they might not ever bear fruit for the rest of us. It’s just that physics is increasingly answering obscure questions which are not only wholly incomprehensible to anyone else, they are mostly irrelevant. String Theory may be a huge deal in physics, but probably won’t change anything for anyone else.
Well, there have been some interesting developments, if not earth shattering. Wasn’t the Schrodinger’s Cat problem basically resolved by reference to the decoherence of indeterminate states whenever they interact with macro-level objects?
Just wondering - is there any equivalent of Rutherford’s “small dark clouds” at the moment? 25 years ago, as I remember, solar neutrinos were a potential candidate - did they ever sort them out?
The problem is, there are plenty of things which could potentially be major breakthroughs in physics but are unclear now, like string theory and working quantum computers. But if they do become breakthroughs, their age will be judged not on when they became firmly established, but when they were first thought up. So “computers” have been around since Babbage, “virtual reality” was thought up in science fiction in the 60’s or even earlier.
Some theories that could potentially be big breakthroughs:
MOND - Modified Newtownian dynamics posits that acceleration behaves differently on the ultra-small scale
Variable Light - Posits that the speed of light might have varied slightly early in the universe
Multi-dimensional gravity - a potential solution to why gravity is so much weaker than the other 4 forces
String theory - explained above
Twenty five years may be too short a time for any major breakthrough to move from theory to generally accepted fact. Special relativity was proposed in 1905 and became mainstream in the 1930’s. General relativity was proposed in 1915 and became mainstream in the 1960’s. Quantum mechanics were proposed in the 1920’s and became mainstream in the 1970’s. So anything that’s newer than 1980 is still working its way through the process of acceptance.
Solar neutrinos have been sorted out, but I think dark matter should count as a “big dark cloud.” There are many proposals as to what it comprises but no one has evidence one way or the other yet.
I think one of the biggest recent breakthroughs has been the discovery that the expansion of the universe is accelerating (or as Chronos put it, dark energy).
Nonsense.
True, SR was still mildly controversial in certain senses into the 1930s - and especially so in particular geographical locations - but it was a central part of any serious education in physics from much before that. Virtually everybody accepted that it was something that had to be learnt and understood.
The second claim has more truth to it. It’s true that GR largely languished until the 1960s, but again that’s hardly because people were rejecting it. People didn’t regard it as a fruitful field to work in, but in general the professionals would have familiar with it and broadly accepted it as a plausible account of gravity. So it was non-mainstream in the sense of being unfashionable to work on, rather than being regarded as probably false.
To claim that QM didn’t become mainstream until the 1970s is, however, simply bizarrely silly.
Personally, I’ll agree with Chronos: one of the biggest changes in the field has been the stunning advances in pinning down the details in cosmology.
Well, I can be a silly person at times. But I stand by what I said.
As I wrote before, acceptance of a major revision is a gradual process. It starts out as a theory. The established scientists read it and most of them say “well, it’s an interesting speculation.” Then a few years go by and it becomes, “it’s a useful model to explain some observed phenomena but that doesn’t make it real.” Then it gets to the point where it’s “It’s generally accepted but there’s no actual experimental proof yet.” Then the experimental proof comes in but by that time the theory’s been out there for so long it’s “well, it’s nice to have corroboration but everybody accepted that theory decades ago.”
Obviously there’s strong motive after the fact to shade earlier opinions. Nobody now wants to be the last person who finally admitted Einstein or Planck were right. In another ten years if String Theory is proven true, every physicist will be saying he believed it back in 1975.
“A new scientific truth does not establish itself by its enemies being convinced and expressing their change of opinion, but rather by its enemies gradually dying out and the younger generation being taught the truth from the beginning.”
The first transistor was made in 1947. You don’t get much more quantum mechanical than solid state electronics. People were making things that relied on understanding quantum mechanics well before the 70’s
