Things 'proved' to be impossible . . . that turned out to be true

Factual Questions
1

We’ve all seen sites on the Internet that list various declarations, predictions, etc. that in retrospect were not just wrong but hysterically funny. Real howlers (and often made by people who should have known better).

Here’s a popular collection (wherein you’ll find such ostensible utterances as ’ “Everything that can be invented has been invented”. – Charles H. Duell, Commissioner, U.S. Office of Patents, 1899’ and ’ “I think there is a world market for maybe five computers.” – Thomas Watson, chairman of IBM, 1943.')

Those are funny, but that’s not what I’m looking for.

I want to know what things have been ‘proved’ to be impossible yet subsequently become reality, or subsequently were proved to exist? (The key point being that they were supposedly ‘proved’ impossible, not just declared to be so.)

My motivation for this thread comes from the fact that I was telling my daughter how there are “all types” of examples where something was proved to be impossible only to have it come true at a later date. But, when I tried to come up with specific examples to illustrate my point, I have to admit that I had a hard time. I mentioned how Eddington (I think it was him) declared that it was impossible for the Sun to be more than some millions of years old since that was the maximum time it could have continued to produce such vast quantities of energy. I went on to explain that his ‘proof’ was true only in a worldview where nuclear energy had not been discovered.

Any other examples where things that were proved as being impossible would eventually be shown to be true, or eventually shown to exist? Again, the key word here is ‘proved’ (not merely asserted as being impossible). I am beginning to think that I was wrong in saying there were “all types of examples”.

Thanks!

2

Usually all you need to do is find someone who made plenty of examples, and some of them are bound to have come true, e.g. isaac asimov. However, even a cursory glance shows plenty of inaccurate guesses, e.g spaceships running on gasoline.

3

Depending on your definition of ‘prove’ (and the age of your daughter), I’d with the Earth being flat and Earth being the center of the Universe.

It’s easy to show that ‘we’ believed both to be true for quite a long time. It’s also easy to see the turning point, why we turned and what changes occurred after the turn.

Also, with things like these (as opposed to something more complex like religion), it’s all somewhat straight forward and mostly based on observable facts*.
*For example “Look, I see Venus, now I don’t, therefore it’s revolving around me” Even though that’s not correct, you can understand why they thought it was true. But as smarter people came along and the telescope showed up (which we could use to see Venus’ moon), we had a new and better understanding. Even if it took a half a century of convincing.

4

I believe that was Lord Kelvin.

5

It was proven that F=ma until we discovered that that was not completely true.

ETA: Oops, that was not really a “proven impossible” example.

6

I think it was Lord Kelvin, certainly not Eddington.

But, of course, that was never a proof of impossibility. At most it it was a good, cogent argument for it. And that is true in general. By definition, if something is truly proved it is true.

7

Yikes! Of course I knew it wasn’t Eddington. I have no idea why my fingers typed that.

I should quit now before I do even more damage.

8

Rereading the op, I don’t think there’s anything proven to be impossible that is now possible. There’s plenty of stuff people THOUGHT was impossible that later proved untrue.

9

In the days when those things were believed, I do not think anybody felt any need to prove them, they were just taken as obvious, although once people started to take seriously the idea that the Earth might be moving, there were some attempts (some quite good, empirically based, ones, too) to “prove” that it could not be.

In the case of the Earth being spherical rather than flat, both the dating of the turning point, and the reasons for it, are rather obscure. We have had several threads on these boards discussing the matter. We know it happened in ancient Greece, somewhere between about 528 and 384 B.C. There are conflicting claims about who was most responsible, but in my view the most likely candidate as the prime mover in the change of opinion was the philosopher Parmedides (born c.530B.C.), but most of his writings (like other writings from that era) are lost, and we can very little evidence about his reasons or what arguments he (or anyone else) may have made.

As for the discovery that the Earth is not the center of the universe, we have almost too much evidence about how this happened. Certainly the story is complex and confusing. In my view the clinching argument came from the compilation of Kepler’s Rudolphine tables, which enabled unprecedented accuracy in predicting the motions of the planets across the sky, but which were founded upon heliocentric assumptions. Of course, Galileo’s telescopic discoveries, and, even more important, his arguments about the nature of motion, played a significant role too, but not as large a one as is often believed.

You are confused. For a start, Venus does not have any moons. You are probably thinking of Galileo’s observations of the phases of Venus. In hindsight, it is possible to construe these findings about Venus’ phases as a “proof” of heliocentrism, but they did not really play a very large role in the arguments about the issue at the time, or in changing people’s views about it, not even, I think, for Galileo himself.

If you are actually thinking about Galileo’s discovery of the moons of Jupiter, that helped to make heliocentrism look a little less wildly implausible than it originally did, but it did not prove a damn thing.

10

It was once (in the late 19th and early 20th centuries) thought to have been proven that both mass and energy were always strictly conserved, until Einstein (and then the discovery of nuclear fusion) showed that they could be interconverted.

11

You’re touching on a really deap and complex question: there is no single accepted meaning for the words proof/proved/proven. I think therefore I am. There are 180 degrees in a triangle’s internal angles. If a tree falls in the woods? Do cigarettes cause cancer? Did O.J. murder his wife?

The farther awy you move from Euclidean geomotry, the farther away you move from any firm concept of ‘proof’.
Simple Darwinian Origion of Species has always been incompatible with the calculated age of the earth. For a long time this was taken as proof that the calculated age of the earth was incorrect. It is now taken as proof that simple Darwinism is not a complete explanation of the Origin of Species. (And the calculated age of the Earth was repeatedly increased).

Dial-up modems could never go faster than 9600. That was true, based on certain axioms. Dial-up modems that work faster than 9600 work differently than older dial-up modems did.

Contients move. They drift. It was long considered imposible: it was proven impossible by everyday and historical experience, and by the nature of materials.

Glass is brittle and shatters. Proved by repeated test and experience. Until it was demonstrated that carefully grown glass fibres can bend like rubber.

Man will never fly. Machines will never fly. Heavier than air machines will never fly. Rockets have nothing to push on.

Troy and Jericho were fictional cities. The Chinese burn rocks for heat. Heavier objects can’t fall at the same speed as lighter objects. Infection is not caused by bacteria (it was caused by bad air). You can’t go faster than 10mph (the air will be sucked out the train and everyone will sufficate).

The reason that the ‘age of the earth’ is such a good example is that it was worked out using arithmetic and the measured properties of materials (as was the maximum speed of a modem). The reason it’s such a bad example is because that’s not how we normally prove things, like guilt or inocence, or health effects, or global warming, or wave/particle duality.

12

That’s why I said “depending on your definition of prove”, but they may work for the OP. If the kid is, say in the 10 year old range, I think they’re good examples of “we know this to be true” followed by “well, maybe not so much”.

Yes, I was thinking of the phases of Venus, that’s what I meant, typing fast, sneaking in edits, referring refreshing my memory via a wiki article, it all happened very fast.
Yes, I’m aware Copernicus was probably the most important person WRT the movement towards the sun being the center of the Universe (or what we knew of it at the time). I made that point because, as I recall from a documentary I saw many years ago it, was Galileo and the telescope (and probably the Venus thing that I’m thinking of) that actually started to change people’s minds. Also, for a kid, it’s easier to point at that than a bunch of tables or equations.

Also, I kept the flat earth thing brief, I don’t know a whole lot about that.

13

And then we got 14.4, 28.8, 56k and then I very clearly remember being told “the copper lines physically can’t handle any more data”. Don’t get me wrong, it took a whole new technology to push the data down the pipes faster, but whoever said that was very wrong.

14

Oh, now that smoking is mentioned, I know of another example:

For years, it was “proved” that second hand smoke causes lung cancer. The government and various groups pushed this through as though it was a proven fact, much like how they pushed marijuana will make you a crazed rapist, to get people not to try it. However, in the original research study, it was only a single person who lived in a closed environment with a 4 pack a day smoker. They also did not explain that plenty of non-smokers also get lung cancer.

15

I didn’t say that (or anything at all about Copernicus). Copernicus was the first person (setting aside the questionable case of Aristarchus) to suggest that the Earth orbits the Sun, but he certainly did not prove it.

Unfortunately, it does take tables and equations (or, at the very least, diagrams) to prove this sort of thing. Even the implications of the evidence from the phases of Venus (which were part of Galileo’s telescopic observations) are quite difficult to explain. The rest of Galileo’s telescopic observations do not come close to “proving” heliocentrism, although many of them do raise difficulties for the versions of geocentrism that were prevalent in his time.

16

Well, if there’s a proof, then there’s a proof. If you later happen to find counter-examples, that only goes to show you that the original “proof” wasn’t a proof after all…

If you’re thinking about merely counter- intuitive stuff, I know no better example than Banach-Tarski’s theorem. Any solid object can be dissected into a finite number of pieces, which,* through rigid motions only*, can be reassembled to form a solid object of larger volume than the original!

(Doesn’t do us much good in the physical world though - there’s simply no way to cut out those slices of atoms that the proof calls for…)

17

i do not really know what you mean by “simple Darwinism”, but this is not true. For a brief time in the late 19th century, the best estimated of the age of the Earth, based on physics, were thought to be too low for evolution to have got as far as it now has by purely Darwinain mechanisms (natural selection). At that time, the main response was to try to suggest other, faster evolutionary mechanisms. This proved to be unnecessary when new physical facts (principally the existence of radioactivity) were discovered, for unrelated reasons, in the early 20th century. At the time when Darwin wrote the Origin, and ever since the early 20th century, the best estimates of the age of the Earth have always provided plenty of time for Darwinian evolution to work.

When did anyone ever think Jericho was fictional? It is a real, inhabited place, even now. It took some work, some digging, to prove the one-time reality of Troy, but for Jericho you just had to go to where it was supposed to be, and you would find it. “In the 19th century, European scholars, archaeologists and missionaries visited often.”

18

I will bet you dollars to donuts that second-hand smoke really does cause (i.e., raise the incidence of) lung cancer, though.

Once you have proved that first-hand smoke does (and this has been proved about as rigorously as anything in science ever can be) it is pretty much a no brainer.

19

Yes, but not by major amounts. I managed to track down a source that says 20-30% higher incidence rates of lung cancer caused by second-hand smoke:

“Inhaling secondhand smoke causes lung cancer in nonsmoking adults (4, 5). Approximately 3,000 lung cancer deaths occur each year among adult nonsmokers in the United States as a result of exposure to secondhand smoke (2). The U.S. Surgeon General estimates that living with a smoker increases a nonsmoker’s chances of developing lung cancer by 20 to 30 percent (4).”

Radon gas inhalation: 8-16% higher incidence rate of lung cancer.

Genetics: 8-14%. ibid.

Asbestos exposure: 3%, but they made a new classification of cancer for asbestos exposure, mesothelioma.

20

Haha, what BS.

Ok, doing the math: 3,000 lung cancer deaths per year by second hand smoke. 4,800 lung cancer deaths from asbestos exposure equals 3% of all lung cancer deaths. Therefore, second hand smoke causes less than 3% of lung cancer deaths. Given that you can’t isolate people with second hand smoke exposure from all other carcinogens, it looks like margin of error.