Tag: physics

No, a black hole can’t be used as a rocket
With a headline like that, I need to introduce some concepts. First, a black hole: if you have enough stuff in a small enough volume, the outside is causally disconnected from the inside. This is normally phrased as “nothing, not even light, can escape”, but that’s a little misleading because… Second: Black holes emit Hawking…

How big might real wormholes be?
AFAICT, there is no actual evidence for real wormholes existing, they are merely interesting ideas not obviously forbidden by known physics. That said, they are fun to think about. Quoth Wikipedia: “The quantum foam hypothesis is sometimes used to suggest that tiny wormholes might appear and disappear spontaneously at the Planck scale and stable versions…

Baryon asymmetry
One day, I might learn enough physics that my questions don’t sound like nonsense to physics graduates. Today is not that day — my working assumption is I sound like a freshman at best, and a homeopath at worst, and will remain so until I put numerical simulations of standard results in general relativity, quantum…

Mathematical Universe v. Boltzmann Brains
I’m a fan of the Mathematical Universe idea. Or rather, I was. I think I came up with the idea independently of (and before) Max Tegmark, based on one of my old LiveJournal blogpost dated “20070112” (from context, I think that’s YYYYMMDD, not YYYYDDMM). Here’s what I wrote then, including typos and poor rhetorical choices:…

Kesslerresistant reallife forcefields?
Idle thought at this stage. The Kessler syndrome (also called the Kessler effect, collisional cascading or ablation cascade), proposed by the NASA scientist Donald J. Kessler in 1978, is a scenario in which the density of objects in low earth orbit (LEO) is high enough that collisions between objects could cause a cascade where each…

I am not a quantum physicist
I am not a quantum physicist. I do not write this prediction thinking that it is true or a novel deduction on the nature of reality. I write this prediction in order to test my own understanding of quantum physics. Given all particles are fields: Fermions are those fields where probability is in the range…

Railgun notes #2
[Following previous railgun notes, which has been updated with corrections] Force: F = B·I·l B = 1 tesla I: Current = Voltage / Resistance l: Length of armature in meters F = 1 tesla · V/R · l F = m · a ∴ a = (1 tesla · V/R · l) / m Using…

Railgun notes
Force on the projectile of a railgun: F = B·I·l B: Magnetic field I: Current l: Length of armature Current = Voltage / Resistance Resistivity of seawater: ρ = 2.00×10^−1 (Ω·m) (because = (Ω/mlength)*(crosssectional area)) Let cavity be 1cm square, consider section 1cm long: Volume: 1 millilitre ∴ mass (m): ~1 gram = 1e3 kg…