There isn't one single "biggest secret," but major cosmic mysteries revolve around dark energy and dark matter, which make up most of the universe but are invisible and poorly understood; the fundamental nature of gravity, especially at quantum scales; and the question of what (if anything) existed before the Big Bang or if our universe is part of a larger multiverse. These unknowns challenge our understanding of reality, from the universe's ultimate fate to its very origins, with scientists actively researching these deep enigmas.
The universe wasn't just expanding—it was doing so faster over time. This unexpected acceleration pointed to the existence of a mysterious, repulsive force that counteracts gravity—now known as dark energy.
Summary: Nearly everything in the universe is made of mysterious dark matter and dark energy, yet we can't see either of them directly. Scientists are developing detectors so sensitive they can spot particle interactions that might occur once in years or even decades.
What is dark energy? It's one of the universe's biggest mysteries: more remains unknown than known about dark energy. It affects the universe's expansion, so physicists are able to infer that dark energy makes up roughly 68% of the universe and it appears to be somehow tied to the vacuum of space.
The two largest pieces of the Universe, dark matter and dark energy, are the two that we know the least about, yet nothing less than the ultimate fate of the Universe will be determined by them. Dark matter tends to pull the Universe together, and dark energy tends to drive it apart.
About 95% of the universe is "invisible" because it's composed of dark matter (around 27%) and dark energy (around 68%), which don't emit, absorb, or reflect light, unlike the normal matter (stars, planets, us) that makes up the visible 5%. Dark matter's presence is inferred through its gravitational pull on visible galaxies, while dark energy is a mysterious force causing the universe's accelerated expansion.
Black Holes: Black holes are the real horror story of space. With gravitational pulls so strong that not even light can escape, they consume everything in their path. Once you cross their horizon, there's no turning back—it's the ultimate cosmic boogeyman.
A black hole is a region of space so dense, nothing can escape its its gravitational pull: not even light or any other form of electromagnetic radiation. Cross its 'event horizon' and you'll disappear forever. And astronomers now think there's a supermassive black hole at the centre of most galaxies.
The number 42 is especially significant to fans of science fiction novelist Douglas Adams' “The Hitchhiker's Guide to the Galaxy,” because that number is the answer given by a supercomputer to “the Ultimate Question of Life, the Universe, and Everything.”
Speak with Certainty (the Universe Responds to Energy, Not Desperation)
In 1 sextillion (10^21) years, the universe will be incredibly cold, dark, and mostly empty; stars will have long died, leaving only black holes, neutron stars, and white dwarfs, with galaxies merging into giant ellipses, and even supermassive black holes will be slowly evaporating via Hawking radiation, heading towards the "heat death" era where the last light sources fade, a timescale dwarfing the current age of the universe.
Return to the Moon
Artemis II, scheduled for launch between February and April sees the return of the first people to the Moon since Apollo 17 in 1972. Three American and one Canadian astronaut will orbit the Moon on a 10 day journey that lays the foundation for lunar landings in the coming years.
Together, dark energy and dark matter make up 95% of the universe. That's almost the whole universe! That only leaves a small 5% for all the matter and energy we know and understand.
It thus consists of a significant portion of charged particles (ions and/or electrons). While rarely encountered on Earth, it is estimated that 99.9% of all ordinary matter in the universe is plasma. Stars are almost pure balls of plasma, and plasma dominates the rarefied intracluster medium and intergalactic medium.
Dark Matter. The search for elusive dark matter puzzles cosmologists. It is invisible, making up a large chunk of the universe - about 27 percent - yet it does not absorb, reflect, or emit light, making it extremely hard to spot.
Believe in possibilities and open to receive them. Allow your own abundant flow, and give allowance for others' good, too. As you practice allowing, you become more fulfilled, because life brings you enough of what you need and you recognize that you already are enough within, too.
For Elon Musk, the number 42, famously from The Hitchhiker's Guide to the Galaxy, signifies humanity's quest for answers, reminding us that asking the right questions about life, the universe, and our purpose is crucial, especially in space exploration, serving as an inspiration for progress and seeking deeper meaning beyond just technology. He's incorporated it into SpaceX's Starship, symbolizing this ongoing search for meaning and the universe's profound mysteries.
8.8 × 1026. Approximate diameter (in meters) of the visible universe (93 billion light years). 1,000,000,000,000,000,000,000,000,000. 1 × 1027. Temperature (in ° Kelvin) of the universe 10-35 seconds after the Big Bang, at the start of the inflationary epoch.
The Ultimate Question is the actual inquiry behind the Ultimate Answer to Life, The Universe, and Everything. The Ultimate Question was sought after the supercomputer Deep Thought revealed the Ultimate Answer to be 42. When Deep Thought asked, Loonquawl and Phouchg were unable to say what the actual question was.
3 AM is considered scary due to folklore calling it the "Witching Hour" or "Devil's Hour," a time when supernatural beings are strong and the veil between worlds thins, but it's also linked to physiological factors like being cold, deep sleep cycles (REM), and increased anxiety when awake in the quiet, dark, and still night. The quiet allows unsettling thoughts to surface, amplified by darkness and strange noises, making mundane things feel threatening.
Your body stretches out, not uncomfortably at first, but over time, the stretching will become more severe. Astronomers call this spaghettification because the intense gravitational field pulls you into a long, thin piece of spaghetti. When you start feeling pain depends on the size of the black hole.
When she brought her samples back in from the airlock, there was a rush of smell, the metallic aroma of space. "That was my favourite experiment – because it smelled." Other astronauts have described a smell akin to charred meat, gunpowder, or burnt electrical wiring.
To date, no one has been victim of a space crime. But because no one nation can lay claim to ownership of space, the idea of a criminal offense committed outside of our atmosphere is something people have already given some thought to.