If the empty space between things is not nothing, what is it? Is there such a thing as empty space?
(Should anyone respond, at least initially, please try to keep your answers relatively simple, i.e. directed toward a lay person, such as I, being able to potentially understand what you are saying.)
It’s empty, but IIRC all of empty space is filled with ‘virtual particles’ that pop into and out of existence in pairs. I don’t understand the quantum mechanics behind the notion of virtual particles, but if you’re interested you can read through the wiki on vacuum energy and click the links you find interesting.
PBS: The Fabric of the Cosmos by Brian Greene talked about that. Space is not just the stage, static and unchanging, an empty space. But space interacts with matter, and matter interact with space. The space bends and stretches, like fabric that stretches. So when a planet moves it tries to move in a strait line, but does not. The planet moves in a circle because of the bends in space which make the circular path. That is Einstein’s relativity idea. Space, with no matter and no energy in it, is not empty… it is stuff, it does exist, it can make a planet circle around, gravity. Space is not just an actor in the theater, but it is the lead actor, the main character.
That’s according to Brian Greene’s video, I am no physicist and do not know Relativity. That video was very nice because it included not just what ideas the host physicist thinks, but why he thinks the ideas, he included some evidence. So that video was special among the other television physicists’ video.
[Edits: expanded the ideas a bit, and polished the dyslexic wording and typos.]
If the empty space between things is not nothing, what is it? Is there such a thing as empty space?
(Should anyone respond, at least initially, please try to keep your answers relatively simple, i.e. directed toward a lay person, such as I, being able to potentially understand what you are saying.)
I’m a lay person.
I’ve wondered about this, is space something or nothing? In other words does space exist? I think if it’s something we don’t have any more information than what that something does.
On whether it’s something I believe the jury is out. I favour it being nothing because that solves otherwise seemingly unsolvable mysteries, like if space is expanding what is it expanding into? If the spatial relationship between stuff is simply changing over time that dissolves that mystery.
The great debate between defining notions of space and time as real objects themselves (absolute), or whether they are merely orderings upon actual objects (relational), began between physicists Isaac Newton (via his spokesman, Samuel Clarke) and Gottfried Leibniz.
Information about this is in the linked video on space that jump in the pit has provided and there is also information about an experiment that took decades to complete that is reported to show that space is something. edit: Another link to the same video (as that one didn’t work for me) http://www.youtube.com/watch?v=wy9gXKwRpXc
If the empty space between things is not nothing, what is it? Is there such a thing as empty space?
(Should anyone respond, at least initially, please try to keep your answers relatively simple, i.e. directed toward a lay person, such as I, being able to potentially understand what you are saying.)
The word comes from the Latin term for “empty”. On this basis, a perfect vacuum would be one with no particles in it at all, which is impossible to achieve in practice.
According to Einstein:
Einstein argued that physical objects are not located in space, but rather have a spatial extent. Seen this way, the concept of empty space loses its meaning. Rather, space is an abstraction, based on the relationships between local objects. Nevertheless, the general theory of relativity admits a pervasive gravitational field, which, in Einstein’s words, may be regarded as an “aether”, with properties varying from one location to another. One must take care, though, to not ascribe to it material properties such as velocity and so on.
QM and empty space:
The development of quantum mechanics has complicated the modern interpretation of vacuum by requiring indeterminacy. Niels Bohr and Werner Heisenberg’s uncertainty principle and Copenhagen interpretation, formulated in 1927, predict a fundamental uncertainty in the instantaneous measurability of the position and momentum of any particle, and which, not unlike the gravitational field, questions the emptiness of space between particles. In the late 20th century, this principle was understood to also predict a fundamental uncertainty in the number of particles in a region of space, leading to predictions of virtual particles arising spontaneously out of the void. In other words, there is a lower bound on the vacuum, dictated by the lowest possible energy state of the quantized fields in any region of space.
So, the concept of empty space is meaningless, an abstraction or as in QM, there is no such thing at all.
If there is always something instead of nothing in the universe, then empty space is a contradiction in terms as space is never empty.
That “A Universe From Nothing’ by Lawrence Krauss, AAI 2009” was a good quantum video, thanks Gdb. At [20:38] he says that we can measure the virtual particles indirectly, and when we measure the spaces between the quarks of a proton, the activity of virtual particles in the empty space adds up to about 90% of the mass of the proton. Also that this is the best comparison between theory and experiment in all of science, measured to ten decimal places in quantum electro-dynamics.
[27:40]The mass that doesn’t shine in a galaxy system, the mass between the galaxies, the dark matter, is most of the mass of the system.
[40:35]The universe is flat, and we know this to an accuracy better than 1%, it has zero total energy, and it could have come from nothing. If you have nothing in quantum mechanics, you’ll always get something.
If the empty space between things is not nothing, what is it? Is there such a thing as empty space? quote]
I appreciate all the responses. So in attempting to consolidating them into an understanding. I would say that what we speak of as space is most correctly thought of as not empty, but as “an extention of matter in relation to other matter that includes a gravitational field and virtual particles which come in and out of existence”. Does that accurately sum it up?
So in attempting to consolidating them into an understanding. I would say that what we speak of as space is most correctly thought of as not empty, but as “an extention of matter in relation to other matter that includes a gravitational field and virtual particles which come in and out of existence”. Does that accurately sum it up?
However, there are these issues to consider:
1. Matter (which has mass) is mainly space and most of its mass comes from its interaction energy fields. From the wiki on matter
The bottom line is that most of the mass of everyday objects comes from the interaction energy of its elementary components.
2. Since Einstein, space and time is combined into single construct, spacetime. From the wiki on space
One can freely move in space but not in time. Thus, time and space coordinates are treated differently both in special relativity (where time is sometimes considered an imaginary coordinate) and in general relativity (where different signs are assigned to time and space components of spacetime metric).
Understanding of spacetime is not as intuitive as of space itself because one cannot move freely in time as in space and also, what is the nature of time, why does it flow and has direction, is still unknown.
I appreciate all the responses. So in attempting to consolidating them into an understanding. I would say that what we speak of as space is most correctly thought of as not empty, but as “an extention of matter in relation to other matter that includes a gravitational field and virtual particles which come in and out of existence”. Does that accurately sum it up?
Not quite. I’ll give you an answer ‘á la kkwan’. From Wikipedia on vacuum state:
In quantum field theory, the vacuum state (also called the vacuum) is the quantum state with the lowest possible energy. Generally, it contains no physical particles. Zero-point field is sometimes used as a synonym for the vacuum state of an individual quantized field.
According to present-day understanding of what is called the vacuum state or the quantum vacuum, it is “by no means a simple empty space”, and again: “it is a mistake to think of any physical vacuum as some absolutely empty void.” According to quantum mechanics, the vacuum state is not truly empty but instead contains fleeting electromagnetic waves and particles that pop into and out of existence.
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The uncertainty principle in the form implies that from the vacuum a particle pair with energy ΔE above the vacuum may undergo spontaneous creation for a short time Δt. These virtual particles are included in the definition of the vacuum.
Understanding of spacetime is not as intuitive as of space itself because one cannot move freely in time as in space and also, what is the nature of time, why does it flow and has direction, is still unknown.
Could it be that organisms have evolved to only perceive time flowing in one direction, as this has been necessary for survival?
Understanding of spacetime is not as intuitive as of space itself because one cannot move freely in time as in space and also, what is the nature of time, why does it flow and has direction, is still unknown.
Could it be that organisms have evolved to only perceive time flowing in one direction, as this has been necessary for survival?
I always have to nitpick when I see this. Sorry. Organisms don’t evolve a certain way because it’s necessary for survival, but rather they survive (and reproduce) because they have evolved whatever it takes to survive (and reproduce).
As far as the direction of time goes, I imagine we perceive it the way we do because we have consciousness, and I doubt consciousness is an adaptation. Rather, I am more inclined to believe it’s a byproduct of something else—I have a few ideas.
Understanding of spacetime is not as intuitive as of space itself because one cannot move freely in time as in space and also, what is the nature of time, why does it flow and has direction, is still unknown.
Could it be that organisms have evolved to only perceive time flowing in one direction, as this has been necessary for survival?
I always have to nitpick when I see this. Sorry. Organisms don’t evolve a certain way because it’s necessary for survival, but rather they survive (and reproduce) because they have evolved whatever it takes to survive (and reproduce).
As far as the direction of time goes, I imagine we perceive it the way we do because we have consciousness, and I doubt consciousness is an adaptation. Rather, I am more inclined to believe it’s a byproduct of something else—I have a few ideas.
I didn’t mean for my wording to confuse the issue of how evolution works. Of course, organisms that survived to reproduce passed on the perceptual abilities that gave their progeny an advantage to survive to reproduce, etc. My thought was that if a chance mutation or gene combination produced an individual organism/s, at any point in history, that could percieve time in a different way, that may have given a disadvantage in survival value, thus would not have evolved. (Not to belabor the point as I realize it is a far out thought.) OTOH, I do have little doubt that consciousness is an adaptation.
That being said I am interested in your ideas (if they are not too far over my head) about what time flow/direction is a by product of.
implies that from the vacuum a particle pair with energy ΔE above the vacuum may undergo spontaneous creation for a short time Δt. These virtual particles are included in the definition of the vacuum.
