cygx

56 ms·

571.
by cygx 7y ago
Why would you think that? FLRW spacetime isn't Minkowski space, thus has nonzero curvature.
572.
by cygx 7y ago
Relativistic frequency shifts can be understood as kinematic effects, namely orientation of photon 4-momentum relative to emitter and absorber 4-velocities. Now, spacetime geometry might be such that there exists space/time decompositi
573.
by cygx 7y ago
Such heuristic explanations are distractions: Locally, gravitational effects (including spatial expansion) manifest as pseudo-forces and hence can be counteracted.
574.
by cygx 7y ago
Specific volume is increasing. If space was finite (but still without boundary - think eg surface of a sphere), so would total volume.
575.
by cygx 7y ago
Spatial expansion is a great heuristic explanation, but it can be misleading: Locally, the cosmological constant will manifest as just another pseudo-force, easily overcome by nuclear and electromagnetic forces holding us together.
576.
by cygx 7y ago
However, if you were to change our relativistic reference frame to match a distance galaxy's [...] In general, you can't do that: There's no distance parallelism in curved spacetimes...
577.
by cygx 7y ago
Kinematical interpretations fall apart really spectacularly I disagree: Relativistic frequency shifts (doppler shift, gravitational shift, cosmological shift,...) can all be understood kinematically: The invariant quantity you have to con
578.
by cygx 7y ago
[Germans] are burning ever more and more coal We've missed our reduction goals, but reducton did happen (about 20% over the last 15 years, and the decrease has even been monotonic since 2013). I keep having to correct this on hackern
579.
by cygx 7y ago
I agree that the multiverse is a bit over-hyped. However, some of the author's statements just rub me the wrong way: Science cannot resolve the existence of either God or the multiverse, making agnosticism the only sensible position.
580.
by cygx 7y ago
https://en.wikipedia.org/wiki/Predestination_in_Calvinism
581.
by cygx 7y ago
https://xkcd.com/1104/
582.
by cygx 7y ago
Note that general relativity requires you to precisely locate all (non-gravitational) energy contributions as they determine spacetime curvature. So while eg the electrostatic potential has an arbitrary zero point, the energy density of the
583.
by cygx 7y ago
Still not quite right: 13.8 Gly is the light travel distance, whereas proper distance at time of emission was less than that. For example, for redshift z=9, light travel time is 13.17 Gy, proper distance at time of absorption (aka comoving
584.
by cygx 7y ago
I don't know if 'feeding expansion' is necessarily the right way to think about this, but by the first Friedmann equation, loss of photon energy will in fact be balanced by the increased expansion rate...
585.
by cygx 7y ago
Super smart, organized and no love for other mammals. Depends on the population: The 'resident' (in contrast to 'transient') orcas in the Pacific Northwest do not eat mammals, even though it would be to their benefit a
586.
by cygx 7y ago
It's precisely because general relativity applies that this is possible. First, note that relative velocity and growth of distance between objects are distinct concepts: Shoot two bullets at 0.9c each in opposite directions, and from y
587.
by cygx 7y ago
How do you propose to perform calculations without data storage (think registers)?
588.
by cygx 7y ago
It's common to measure total electricity production of a nation (eg 650 TWh for Germany in 2018) that way...
589.
by cygx 7y ago
It's doubtful you'll be able to make such a scheme work: Information processing tends to involve storage and retrieval of data. That's not really possible in the thermodynamic regime. You'd have to do all your processing
590.
by cygx 7y ago
You're right. The dividing line is whether or not you think the physical and the mental necessarily coincide, which is in principle an orthogonal issue.
591.
by cygx 7y ago
Thoughts are a process, so if they were supported by a crystal lattice, that lattice would have to go through changes. As to your other point, the ergodicity of the system at the very least places a limit on the timescales over which consci
592.
by cygx 7y ago
If you're not a dualist, thoughts necessarily have to be accompanied by some change of state of the material substrate.
593.
by cygx 7y ago
I find it reasonable to assume that for thought processes to occur, there must be some processing, so rocks are out. A more interesting example would be, say, trees, which do communicate with each other to some degree. Is that accompanied b
594.
by cygx 7y ago
Possibly power-to-gas. Methane production at 75% efficiency has been demonstrated a while ago[1] and claims of potential round-trip efficencies of up to 80% have been made[2]. This is relevant because Germany's existing gas infrastruct
595.
by cygx 7y ago
The Greens nearly doubled their result in the European elections, coming in second at 20.5% after the CDU at 28.9%. They were up +4.6 points in Brandenburg and +2.9 points even in Saxony, making them one of the very few parties that didn&#x
596.
by cygx 7y ago
You can: https://en.wikipedia.org/wiki/Maxwell%27s_equations_in_curve...
597.
by cygx 7y ago
It's also true if you want F = ma to continue to hold in special relativity, then m is a velocity-dependent matrix. Not if you describe things in terms of four-forces and four-accelerations, which restores the simple proportionality.
598.
by cygx 7y ago
Because gravity is a pseudo-force: Free fall is inertial motion, tracing out a straight path through a curved spacetime. In a way, it's more like m·(a - a_grav) = F_nongrav
599.
by cygx 7y ago
At first glance, no.
600.
by cygx 7y ago
Cogeneration happens at the gas-to-power side of things. Doesn't help you with electricity generation, but that's ok as the goal is reduction of emissions across all sectors.

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