de Brogli? wasnt that a character in Jungle Book?..way over my head these answers so ill just nod and say hmmmmm
mowgli de Broglie - that should be a good name for a pet
I'll try to explain because science is no good if it's sitting bottled up in academia. But if I get too boring, just tell me to stop
So, let's start with light. Young showed that light can create interference patterns (patterns of dark & light regions) - but only waves do that! With a wave, you have the concept of peaks (light regions) and troughs (dark regions), wavelength, and frequency, and here was light behaving in this manner. So people said if light acts like a wave, then it must be a wave.
But then Einsten did a different type of experiment in which he used light to eject electrons from a metal surface. A higher intensity of light should knock off more electrons that a lower intensity light, correct? The light is essentially tranferring some energy to the metal's electrons which ionizes them. The problem was, the light's frequency (number of cycles per second) was having an effect on the electrons. That's not explained by waves because the energy of a wave is from its amplitude (intensity). Something else was going on. So he proposed that light consisted of little packets called photons and their energy was related to their frequency. This explained the results!
So which is it? It depends on what you do to light. If you set up Young's experiment and then used that light to do Einstein's experiment, you'll be forced to conclude that it is both a localized particle and non-localized wave. Does that sound messed up? It's our only explanation of light
So what about matter? things that have mass, like an atom or an electron. People were trying to explain the line spectra emitted from different atoms when you ionize its electrons. Why did the atom emit light only at specific, discrete wavelengths? Something was constraining the electrons, and therefore the emitted light. De Brogli proposed: what if we think of the electron as being a circular wave existing all around the atom instead of a tiny point particle revolving around the nucleus. Basically, let's treat the electron as a wave, and bring in the idea of wavelength. Why? Because this is the constraint on the electron! It can only exist if its wavelength is such that it 'fits' - like imagine placing rings of different diameter on your fingers. Depending on which finger, some rings will fit, others wont. So here, we have matter behaving like a wave! At the level of atoms and electrons, it's easy to observe this wave behavior. We say that all matter has wavelike properties, but it is too tiny to measure for things ordinary size like an apple or something.
Basically, they observed something and tried to come up with an explanation that fits. Even if the explanation was completely crazy, if it fits the observations, then use it to estimate other things. If our estimate agrees with Nature, then we're confident with the explanation. But that brings up the thorny question: does it really exist like that or is it just a trick to make things work? Would an alien with extra senses/perception come up with the same explanation?
Which brings me to time - in Slaughterhouse Five by Vonnegut, there are aliens who can 'see' time the way we can see space. They can see it as if you unrolled a map and laid it flat on the table. But us primitive beings are forced to measure time by essentially counting, and using real-life events as markers. We almost start thinking of the ticks & markers as being time itself. Something funny happens to these ticks & markers when you travel close to the speed of light - but I better leave that for another post.
random fact of the day: People usually think of scientists as being dry & boring, but Schroedinger was a notorious sex fiend