Kinetics • Relation between work and energy
Here is a powerful collection of bad relationships quotes to help you think about your best next steps when your personal relationships are not where you want. David Bly; "Success is focusing the full power of all you are on what you have a If you don't enjoy getting up and working and finishing your work and sitting . A growing relationship can only be nurtured by genuineness. Each relation is the place fie lieu] within which power manifests itself, is a space within which work [travail], that is to say energy and information, has 31 " tout point d'exercice du pouvoir est en meme temps un lieu de formation du savoir.
A direct comparison with a random null hypothesis would be the creationist independent 'poofing' of all species. I feel better now. No matter, I think. I can't say I understand general relativity this is a theme! I hear there is a lack of global energy principle which would correspond to Noether's energy-time I think, as that derives from a global symmetry as I understand it no Noether either: The reason redshift violates energy conservation is because you look over cosmological volumes that expand, not a closed system.
I hear at least one of the local energy principles correspond to flat space zero energy.
Mechanics: Work, Energy and Power
But there is a way to assess global energy by looking at the system behavior of a cosmology, GR and global solutions and all. Then it turns out universes are thermodynamically closed systems with an attractor that asymptotes to zero energy. The instinctive answer might be that the energy is infinite. However, the open FRW universe dilutes its matter density to an infinite extent and is hence asymptotic to Minkowski spacetime.
You can look up "Zero-energy universe" in Wikipedia. A similar but simpler idea was that the scalar Higgs field could be a field of inflation. Seems it didn't work with the current parameters for the Higgs. Not a definitive analysis, I'll give you that. Matthew Francis post explains this. The top two pictures shows how normal gases behave: The bottom two pictures show what happens if you could somehow confine dark energy: Well, it is enough that it is "a huge factor". But pushing back the surround?
Normal positive pressure does that. Appropriate analogy accorded to appropriate phenomena. Physics is easily confusing as it is, lets not increase the opportunity for it, hmm? Log in to post comments By Wow not verified on 27 Jul permalink Hey!
Thanks for answering my question! I saw your mention of a trillion years, but when I did some Googling I ran across pages asserting that it could happen as little as 60 billion years from now, or even less.
Do we have a commonly accepted answer for how far in the future the rip is, and how confident are we of that figure? Log in to post comments By Alexander Wolfe not verified on 27 Jul permalink Wow, Pressure is what it's been called since long before I came on the scene. It predated Einstein and, as far as I know, goes all the way back to Euler.
It might not be intuitive because it doesn't behave the same way towards curvature as it does towards matter, but it's the only thing to call it.
Alexander, That would depend on how different from a cosmological constant it is. A trillion years is about as long as it will take for the closest unbound galaxies to disappear completely from our night sky in the case of a cosmological constant, but a Big Rip could, with the current constraints, happen as "early" as about 80 billion years from now.
See the excellent post from astrokatie linked under my name for a deeper discussion of the Big Rip and timescales.
Log in to post comments By esiegel on 27 Jul permalink Thank you Ethan - very interesting. I was meaning to ask a question as well - "if DE is adding more space between us and distant galaxies, and a galaxy is said to be 1 billion light years from us, does that mean that the galaxy: I learned a lot which I like, and I didn't understand bits which I also like 'cause it stretches my brain.
I have to read carefully what Ethan said and Wow and the missing link. Log in to post comments By OKThen not verified on 29 Jul permalink Ethan, thanks for taking the time to answer my question. Log in to post comments By Sinisa Lazarek not verified on 29 Jul permalink Ethan -- In the comments thread that emanated from your December,post on Dark Energy, you promised us a column "next week" on this question of pressure.
Judging by the current thread as well as those in December, it may be time for that column! Log in to post comments By Patrick M.
And I admit to my ignorance. I've read what you've said, followed links and done a few searches. But I have no idea if my question has been answered or ignored by any of you. Please don't worry about being polite. If my question is stupid just tell me that and why as best you can. If my question is sensible but too difficult to even guess an answer you know infinities everywhere then tell no one can answer my question yet but we guess it is worn because of this or that.
So if someone can give me a clue, an imperfect answer; I'd appreciate it. So let me paraphrase my question and thought process same idea as above 1 negative pressure means the universe is inflating i. So that's a lot of real sucking, i. So we got a balloon universe being blown up everywhere inflation i.
So maybe despite the eternal inflation maybe I use this term incorrectly ; maybe the persistent billion black hole positive pressure leaks will leave the universe essentially looking the same in 1 trillion years. Now this is a very dynamic looking the same; and I suppose it may require maybe extra dimensions, curved space at least in the vicinity of the black hole. If the force is up and the displacement is to the right, then the angle is 90 degrees.
This is summarized in the graphic below. Power Power is defined as the rate at which work is done upon an object.
What are energy and work? (article) | Khan Academy
Like all rate quantities, power is a time-based quantity. Power is related to how fast a job is done. Two identical jobs or tasks can be done at different rates - one slowly or and one rapidly.
The work is the same in each case since they are identical jobs but the power is different. The equation for power shows the importance of time: Special attention should be taken so as not to confuse the unit Watt, abbreviated W, with the quantity work, also abbreviated by the letter W.
Combining the equations for power and work can lead to a second equation for power. A few of the problems in this set of problems will utilize this derived equation for power. Mechanical, Kinetic and Potential Energies There are two forms of mechanical energy - potential energy and kinetic energy. Potential energy is the stored energy of position. In this set of problems, we will be most concerned with the stored energy due to the vertical position of an object within Earth's gravitational field.
Kinetic energy is defined as the energy possessed by an object due to its motion.
Empty space has more energy than everything in the Universe, combined | ScienceBlogs
An object must be moving to possess kinetic energy. The amount of kinetic energy KE possessed by a moving object is dependent upon mass and speed. The total mechanical energy possessed by an object is the sum of its kinetic and potential energies. The work done by the force of gravity is the force multiplied by the distance, so if the object drops a distance h, gravity does work on the object equal to the force multiplied by the height lost, which is: An object with potential energy has the potential to do work.
In the case of gravitational potential energy, the object has the potential to do work because of where it is, at a certain height above the ground, or at least above something. Spring potential energy Energy can also be stored in a stretched or compressed spring. An ideal spring is one in which the amount the spring stretches or compresses is proportional to the applied force. This linear relationship between the force and the displacement is known as Hooke's law.
For a spring this can be written: The larger k is, the stiffer the spring is and the harder the spring is to stretch. If an object applies a force to a spring, the spring applies an equal and opposite force to the object.
What are energy and work?
This is a restoring force, because when the spring is stretched, the force exerted by by the spring is opposite to the direction it is stretched. This accounts for the oscillating motion of a mass on a spring. If a mass hanging down from a spring is pulled down and let go, the spring exerts an upward force on the mass, moving it back to the equilibrium position, and then beyond. This compresses the spring, so the spring exerts a downward force on the mass, stopping it, and then moving it back to the equilibrium and beyond, at which point the cycle repeats.
This kind of motion is known as simple harmonic motion, which we'll come back to later in the course. The potential energy stored in a spring is given by: