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Thread: To know or not to know

  1. #1
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    Question To know or not to know

    We do not know if before the beginning there was knowledge at all, but since we think we
    have knowledge now, we think that there would be knowledge to come, at least at some
    point after the beginning. Before the beginning we do not know if it, if anything, was
    similar or different from what we think we know now. We can only imagine what was, if
    anything. If so, if different, it can not be described unless in terms of the known.

    If we say 'I don't know', at least we know that we don't know something, if anything. Not
    knowing what you don’t know makes it impossible to even be aware of what is beyond your
    present knowledge, or even to imagine that there would be anything.

    Nor can we imagine what is impossible to know because we have no means of sensing it. All
    we can hope for is to improve our techniques of sensing information, our ability to
    select what’s relevant and rely on our brain to put it all together in a coherent way,
    which will allow us to gain insight in how it all works: that is, if it would be
    different from what we think it is. For what if we think what it is, is no more than our
    senses make of it?

    If it is what it is because we think it is that way, reality would be no different from
    what we think it is. If some of us think the same way about what it is, it might seem
    that reality is not much different from what we think it is, because we all came to the
    same conclusion. We might think that a reality exists independent of what we think of
    what it is, and the best way to know about it is to have some sort of consensus about
    what it might be. But what if reality exists only in our thinking? What if we exist only
    in our thinking? What if our thinking only exists in our thinking, would our thinking
    exist at all? And if everything we perceive exists somehow or another independent of our
    thinking, how much is our thinking capable to change things, or do they only change in
    our perception? And if not through our thinking as such, is our interaction between our
    perception of what we think things are and what they really are, of any influence on
    changing what things really are?

    A scientific theory is our best guess at some point in time of what we perceive. We do
    not know if our perception has any relationship with something different from us. Any
    representation of the world outside, if any, is produced by the (conscious) brain in
    cognitive terms of spaces, shapes, geometrical forms, symbols (language, mathematics,
    images), etc.

    Just a few centuries ago mankind wasn't aware (didn't think) of how far time and space
    stretched into the past and outside, nor do we yet know now how long it will last and how
    far it will go.

  2. #2
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    Default Emergent gravity

    New theory of gravity might explain dark matter

    8 November 2016
    A new theory of gravity might explain the curious motions of stars in galaxies. Emergent gravity, as the new theory is called, predicts the exact same deviation of motions that is usually explained by inserting dark matter in the theory. Prof. Erik Verlinde, renowned expert in string theory at the University of Amsterdam and the Delta Institute for Theoretical Physics, just published a new research paper in which he expands his groundbreaking views on the nature of gravity.

    In 2010, Erik Verlinde surprised the world with a completely new theory of gravity. According to Verlinde, gravity is not a fundamental force of nature, but an emergent phenomenon. In the same way that temperature arises from the movement of microscopic particles, gravity emerges from the changes of fundamental bits of information, stored in the very structure of spacetime.


    Newton's law from information

    In his 2010 article, Verlinde showed how Newton’s famous second law, which describes how apples fall from trees and satellites stay in orbit, can be derived from these underlying microscopic building blocks. Extending his previous work and work done by others, Verlinde now shows how to understand the curious behaviour of stars in galaxies without adding the puzzling dark matter.


    Puzzling star velocities

    The outer regions of galaxies, like our own Milky Way, rotate much faster around the centre than can be accounted for by the quantity of ordinary matter like stars, planets and interstellar gasses. Something else has to produce the required amount of gravitational force, and so dark matter entered the scene. Dark matter seems to dominate our universe: more than 80% of all matter must have a dark nature. Hitherto, the alleged dark matter particles have never been observed, despite many efforts to detect them.


    No need for dark matter

    According to Erik Verlinde, there is no need to add a mysterious dark matter particle to the theory. In a new paper, which appeared today on ArXiv.org, Verlinde shows how his theory of gravity accurately predicts the velocities by which the stars rotate around the center of the Milky Way, as well as the motion of stars inside other galaxies. 'We have evidence that this new view of gravity actually agrees with the observations,' says Verlinde. 'At large scales, it seems, gravity just doesn’t behave the way Einstein’s theory predicts.'
    At first glance, Verlinde’s theory has features similar to modified theories of gravity like MOND (modified Newtonian Dynamics, Mordehai Milgrom (1983)). However, where MOND tunes the theory to match the observations, Verlinde’s theory starts from first principles. “A totally different starting point,” according to Verlinde.


    Adapting the holographic principle

    One of the ingredients in Verlinde’s theory is an adaptation of the holographic principle, introduced by his tutor Gerard ’t Hooft (Nobel Prize 1999, Utrecht University) and Leonard Susskind (Stanford University). According to the holographic principle, all the information in the entire universe can be described on a giant imaginary sphere around it. Verlinde now shows that this idea is not quite correct: part of the information in our universe is contained in space itself.


    Information in the bulk

    This extra information is required to describe that other dark component of the universe: the dark energy, which is held responsible for the accelerated expansion of the universe. Investigating the effects of this additional information on ordinary matter, Verlinde comes to a stunning conclusion. Whereas ordinary gravity can be encoded using the information on the imaginary sphere around the universe only - as he showed in his 2010 work - the result of the additional information in the bulk of space is a force that nicely matches the one so far attributed to dark matter.


    On the brink of a scientific revolution

    Gravity is in dire need of new approaches like the one by Verlinde, since it doesn’t combine well with quantum physics. Both theories, the crown jewels of 20th century physics, cannot be true at the same time. The problems arise in extreme conditions: near black holes, or during the Big Bang. Verlinde: 'Many theoretical physicists like me are working on a revision of the theory, and some major advancements have been made. We might be standing on the brink of a new scientific revolution that will radically change our views on the very nature of space, time and gravity'.


    Article reference

    Emergent Gravity and the Dark Universe, E. P. Verlinde, 2016 Nov 8
    https://arxiv.org/abs/1611.02269
    Published by UvA Persvoorlichting

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