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>That's a popular science analogy. Don't use it literally.

um, so what does it really means when scientists say that gravity warps the spacetime

>Albert Einstein proposed that massive objects warp and curve theuniverse, resulting in other objects moving on or orbiting along thosecurves—and that this is what we experience as gravity

https://www.science.org.au/curious/space-time/gravity

edit: what I'm saying if the bending of space we experience as gravity, we can experience simultaneous stretching of space as expansion

I don't think so, there is no burning involved. I don't think this is line emission, this is a solid incandescent piece of metal.
edit: why i said i don't think so is because the wiki mentions this effect as separate and distinct from the thermal emission of the solid.

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> If large masses like stars etc cause stretching of space

That's a popular science analogy. Don't use it literally.

Every mass contributes to a slowing of the expansion, doesn't matter if we consider a proton, a star or a galaxy.

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The genes are inside every single cell. Those are the ones getting mutated. When they mutate our body will take care of it (hopefully) and get rid of them or the cell undergoes programmed cell death called apoptosis. If apoptosis fails and body cant clear it out, may have problems

It's quantum physics

Different atoms prefer to produce photons at different wavelengths. That's why copper burns blueish green, strontium burns red, and sodium burns yellow.

After it absorbs energy from the flame, It's electrons drop back down and tend to produce more light in the visible spectrum than the infrared

> matter slows down the expansion of the universe

I can't understand it. If large masses like stars etc cause stretching of space, why not assume that galaxies, clusters and filaments also stretch space between them, which would cause the expansion of the universe? Process of transforming energy into matter would fuel that expansion of space on a large scale.

They have two special muscles. One is a sheet of muscle between the lungs and rest of the guts, beneath the lungs and attached to the shell, which squeezes the lungs to force gas out. The other is a sheet of muscle covering the rear opening of the shell (where the hindlimbs stick out). It's concave when relaxed, but flattens out when active, pulling the viscera back and expanding the body cavity. Since the guts don't change volume much on that short of a timescale (seconds), this forces lung expansion and inhalation.

Check the first two paragraphs and first figure of this paper: https://www.nature.com/articles/ncomms6211

If all the cancer cells and precancerous cells (cells with some of the mutations needed to be cancerous but not all) are dead, you can get a new cancer from new mutations, but it's not more likely than before you got cancer. It's not the cancer coming back, it's a new one. Killing the precancerous cells is easier than the cancerous cells because they are localized around the main tumor. They can't go through metastasis and move away. They are killed when the main tumor is removed or destroyed with radiation.

Often not all cancer cell are dead, that's why the cancer comes back. Then it's the same cancer. Even if it appears in a different location, it's still the same one, it just got to the new place through metastasis.

Right, the infalling object can't escape into our universe after it crosses the event horizon. In the idealized black hole construction, the infalling object will, however, escape into another universe (via a white hole) if it avoids hitting the singularity.

In general, one single mutation won’t give you cancer. You need some mutations on specific genes to develop it. Some of this mutations may come with the gene set you inherited from your parents, and all your body cells get this mutation. Other mutations develop during your lifetime by different reasons, but this mutations are not present on every cell your body have, but only on some of them. Everyday you get mutations on your DNA, but most of the cells that get these mutations get eliminated by the immune system. The problem is when you get the set of mutations needed for a cell to divide uncontrollably, and the immune system does not detect this. Cancer cells are more susceptibles to certain treatments that regular cells, so you can use these treatments to eliminate them. If you eliminate all cancer cells, you are cancer free, if not, you might get cancer again. People that inherit mutations from their parent genes, are also more susceptible to get cancer again, as they need fewer other mutations in their cells to develop it.

If you kill all the cells with the mutation, you get rid of the cancer. It can come back when you dont kill all the cancerous cells or another mutation happens. Cancerous cells are a lot more common than you think, but usually your immune system takes care of it.

Edit: important note its just some cells that mutate its not all the cells in your body.

Found the answer online.

A Kerr black hole (one that rotates around its axis), has an ergosphere in which you can enter and get out because of the Lense-Thiring effect. Basically, the rotation of the black hole drags space-time and changes the frame of reference in which you move. Therefore if an object passes into the ergosphere it can still be ejected by gaining energy from the rotation.

But! If anything passes the event horizon, the surface limit where the escape velocity is the speed of light, then no material thing can escape.

It's on daviddarling.info.

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Thanks, I appreciate the response. I like the discussion of convergence and the care to consider the shape of the volume in the limit of infinite size.

It wouldn't be an event horizon if you could get out.

Newtonian mechanics doesn't have event horizons so it's important to consider general relativity here. If you are inside the photon sphere (1.5 times the radius of the event horizon for a non-rotating black hole) then tangential motion makes you fall in faster. Every attempt to orbit there makes you spiral into the black hole.

> it would require the velocity to exceed the speed of light when you're approaching the periapsis

No! Once you pass the event horizon your worldline will terminate at the singularity. There is no way you would be able to exit the black hole, even with a hypothetical engine that provides infinite thrust.

Exiting the black hole is equivalent with going back in time. Approaching the singularity is equivalent with going forward in time. How do you accelerate away from tomorrow?

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