So, scientists – the cool astrophysicists – have stepped up and said, “Hey, you know this thing called dark matter that’s been giving us a headache? Turns out, we might not really need it to explain all the crazy stuff happening in the universe.”
Dark matter supposedly makes up a hefty 80 percent (or more) of all the matter out there but guess what? We can’t see it. It’s like a ninja – doesn’t give off, reflect, or absorb any light. Sneaky, huh? Instead, we know it exists because of its gravitational tug on things we can see, like making starlight bend in funky ways.
Now, gravity is that magical force that pulls everything with mass or energy towards each other. Think magnets, but on a cosmic scale. Astronomers have long suspected that dark matter, being invisible to our eyes, throws in some extra gravitational oomph.
But wait, here comes Richard Lieu with a hot take. He’s proposing a radical theory that could shake up the dark matter party.
Lieu suggests that the extra gravitational push holding galaxies together might not need dark matter after all. Instead, he’s waving the flag for these shell-like defects found all across the cosmos.
These defects probably popped up during the universe’s baby years, during some massive transformation phase where everything decided to switch styles at the same time.
According to Lieu, these “topological effects” are like super dense regions in space, maybe shaped like linear cosmic strings or even 2-D spherical shells.
In a nutshell, these sassy shells have a positive mass layer inside and a negative mass layer outside, which sounds like a zero-sum game, but stars on these shells feel a strong gravitational pull towards the center.
Now, Einstein said gravity bends both space and time, creating a funky bond between objects, no matter their size. Gravity doesn’t play favorites – it can sway even massless photons, like how light bends around massive celestial bodies.
Lieu’s theory about these massless shell-defects could explain why stars in galaxies move the way they do, maybe better than dark matter. Intriguing, right?
He’s saying, “Hey, forget hunting for dark matter. These shells might be the answer.” But hold up – how the heck do massless shells even form? Mystery still unsolved!
Now, before we ditch the dark matter quest completely, let’s remember – finding these cosmic shells would be the real deal. It’s not enough to just have a cool theory; we need to back it up with solid observations. Challenge accepted!
Curious about the full details? Check out the study in the Monthly Notices of the Royal Astronomical Society.