What do we know about our Universe now that we didn't till recently?

Einstein was proven correct on how the universe is expanding.

Define “recently”.
Depending on the definition of “recently”, knowledge may include that the earth is not the centre of the universe, that planets revolve around the sun in elliptical orbits, that the Milky Way is not the only galaxy in the universe, that the universe emerged in a “big bang”, that the universe is expanding, that the universe’s expansion is actually accelerating, that all the normal visible matter in the universe is only 4 percent of the universe’s whole mass, that 96 percent of the universe’s mass is dark matter and dark energy (matter and energy that we cannot see directly and do not know what they are, hence the name “dark x”), that there are supermassive black holes at the centre of the galaxy, that there is zeropoint energy in vacuum that excerts actual pressure on space and matter and that there are particles that constantly pop in and out of existence in a total vacuum. And more.
@SpatzieLover Einstein actually believed that the universe is neither expanding nor contracting, the so called “steady state” theory. That is why he introduced the “cosmological constant” into his equations so that mathematically, the universe was constant in size.
After it was discovered that the universe is expanding, he called the cosmological constant his “biggest blunder”.

@ragingloli Good answer !
That whole dark energy / dark matter thing is very peculiar and profound.

We’ve known since the late 1920s that the universe is expanding, thanks to the work of Hubble (after whom the telescope was named). It wasn’t until 1998 (“recently”), however, that the expansion was discovered to be speeding up and not slowing down as had been previously assumed. This astounded everyone and has required a whole new outlook on cosmological theory and existence of “dark energy” to drive the expansion.

@gasman
I like reading and wondering. I also like sharing and learning. They are finding out more all the time.
Do you believe there is a Multiverse?

@philosopher : I believe wholeheartedly in the multiverse. I’ve read all of Terry Pratchett’s Discworld series.

It was recently shown that not only are there other universes, but that they can collide and “bruise”. Ours has four times with nearby ones.

@Hawaii_Jake
I read as well and I think the Multiverse Theory would explain a lot. I like reading Dr. Kaku’s books. I do think it will eventually be documented somehow.
I watch Science Channel and look for these type of shows.
@incendiary_dan
If you have such documentation can you post it?

Planets are common. There are billions and billions of them in our galaxy alone. Many of them are probably the same size as Earth. Statistically speaking some of them certainly lie within the “habitable zone.”

I guess we’ve always (at least in the modern era) suspected this was the case, but we only started observing these extrasolar planets in the 1990’s.

We know what the atmosphere of Jupiter is made of firsthand because we actually dropped a probe through Jupiter’s clouds in 1994, and then dropped an entire spacecraft(spacecraft) through the clouds a few years later.

Quantum field theory is also a big deal, but I’m not going to pretend that I understand it. Well maybe a little. Matter is made out of fields. Every point on a field has a value. We see some of these values as “particles.” Here’s a video that sort of explains it.

Oh, I forgot the coolest thing! CPT-symmetry.

Take any particle. Give it an opposite charge. Mirror its position in space. Make it go backwards in time. There is no way to distinguish the flipped particle from its original.

I am not sure how recent you want, but in the last few months they have realized the dramatic frequency of planets orbiting stars, and how the Universe is not only expanding, it is speeding up, not slowing down.

The Andromeda galaxy is on a collision course with the Milky Way. It’s estimated that the collision will happen in about 3–4.5 billion years.

@Brian1946
LOL I heard that one.
I think by than humanity will be able to travel the Universe. If we survive.

@philosopher The multiverse concept, where our observable universe is but one small bubble of an infinite fractal structure that keeps generating new universes, is intriguing, but we have no evidence supporting this, nor does it seem possible (at present) that evidence can ever be found. The intellectual appeal of the multiverse is that it eliminates the problem of why our particular universe seems to special and fine-tuned as it is: There’s nothing special about a universe that is just one of an infinite number of universes, all different from each other. I just finished reading A Universe from Nothing by Lawrence Krauss, who makes this point.

@Brian1946: Not to worry: when galaxies collide, the individual stars within them seldom collide. It might be hard to tell if the collision is even taking place from our limited vantage point.