Everything posted by Markus Hanke
-
How does your brain change after you learn a new language?
Funny, I’ve had a similar experience. I’m generally good with languages (fluent in 2, varying levels in another 7, several more on my ‘to learn’ list), but French really didn’t do it for me, even after five years of formal study in High School.
-
Universe is (In)Finite?
This is not how a gravitational singularity is defined - the actual definition is that it is a region of spacetime that is geodesically incomplete. I should also mention that singularities are not all point-like, and that they technically are not part of the manifold. No. The type of black hole you appear to be discussing (there are many different types with very different properties!) exists in vacuum, so the energy density is everywhere zero. Also no. Geodesic incompleteness is an invariant property on which all observers agree. And the central message of relativity is actually the exact opposite - that the world is described in terms of covariant and invariant properties subject to certain symmetry groups. Yes it is. Gravitational waves are described by the same mathematical objects as any other gravitational field. They are essentially a time-dependent gravitational field that oscillates in a specific way. Every gravitational radiation field has a source by which it is generated, so this distinction does not exist.
-
I found out how Universe Works
I think you typed this just as I moved the thread
-
I found out how Universe Works
! Moderator Note Moved to ‘Speculations’ section.
-
Length contraction in a block universe must be an illusion
I am genuinely of the opinion that all my replies were direct responses to something you posted, and didn’t ignore the salient points; and yes, I had to repeat myself - several times over - because there is only one mechanism explaining these observations, so there are only so many responses one can possibly give. How about the colliding gold ions at the RHIC, which I referenced earlier? I personally feel that’s an even better example, because the experiment can be repeated in a controlled manner in a lab, and contains fewer unpredictable variables.
-
Length contraction in a block universe must be an illusion
The very title of the thread already gave it away right from the start, but I had been hoping that explaining the theory plus listing experimental evidence might have had some effect at least. Sadly though, at this point the best term I can think of to describe this thread is ‘sealioning’.
-
What is entanglement, both classical and quantum and what is the difference between these ?
This appears to be better suited for a new, dedicated thread; it doesn’t quite fit into this discussion.
-
Length contraction in a block universe must be an illusion
This isn’t a contradiction at all, because these are different observers performing a measurement the outcome of which is observer-dependent, since they’re measuring something that isn’t intrinsic to the train, but describes only their relationship to it. It seems to me that we are just repeating both question and answer over and over again, to no avail at all it seems. So let me ask you this - are you actually interested in the explanation, or have you made up your mind already that relativity must be wrong? Just be honest.
-
What experimental verification exists to substantiate that light from a receding light source travels at c to a relatively stationary destination?
The invariance of c is a direct consequence of Lorentz invariance, so any experiment testing this symmetry would verify that finding. There is a large body of such experimental tests. But you don’t even need any reference to relativity for this, because it also follows directly from Maxwell’s equations - the propagation velocity of light in vacuum depends only on vacuum permittivity and permeability, and nothing else. So it is naturally invariant between frames, since these are fundamental constants. And I think we can all agree that Maxwell is not under contention.
-
Length contraction in a block universe must be an illusion
The particles are one meter apart as seen from a specific frame of reference. A different observer will measure a different distance. All observers are right, in their own frames. A specific Length is thus a relational property, and not somehow intrinsic to the object. I guess-timate that this has been pointed out now at least ~10 times or so, in different ways be different posters.
-
Can you be a scientist and still believe in religion?
I’m an amateur science enthusiast; I’m also a Buddhist monk. In principle you are right - the issue should not be of concern in Buddhism. In practice though it depends on which of the many schools you look at, and even who you are talking to. Many Buddhists very much do have various supernatural elements in their world view, or interpret some of the central ideas in supernatural ways; scriptural literalism and fundamentalism sadly also happens. In fact, those Buddhists who don’t do any of those things are very much in the minority. I personally see no issue (or else I wouldn’t be on here), since my ‘personal Buddhism’ does not contradict any scientific findings that I am aware of, and vice versa - they are very much dealing with two separate domains of enquiry, both of which are limited in their applicability.
-
What is entanglement, both classical and quantum and what is the difference between these ?
Yes, of course. But what I meant here isn’t the maximum correlation (which is always 1 of course), but how it is distributed as a function of detector angle in the classical Bell experiment (graph taken from Wiki). You can see the quantum correlation is stronger than classical correlation (local realism):
-
Delayed choice experiment (split from Question: Does the Double Slit Experiment prove Free Will?)
Not when they are hitting the screen - they behave like particles there. They also behave like particles in other circumstances, such as eg the photoelectric effect. Apart from this being inconsistent with the specific experiment linked to by swansont, it also runs counter to double-slit type experiments done with quantum objects other than light, which don’t exhibit the property of polarisation. As already pointed out numerous times, the observed effects are independent of the nature of the quantum object - they happen with photons, but also with electrons, C60 molecules, or any other quantum object. The common denominator is always the availability of which-path information.
-
What is entanglement, both classical and quantum and what is the difference between these ?
I must admit I’m confused about the last few comments. Entanglement is a correlation between measurement outcomes, in the sense that the multi-partite system is non-separable. Knowing whether a system is entangled requires one to take measurements on all parts, and then bring the results together and compare them. The only thing special about quantum entanglement is that the correlation is stronger than classically allowed.
-
Delayed choice experiment (split from Question: Does the Double Slit Experiment prove Free Will?)
I don’t think this is a useful comment - you cannot know to what degree people here are really familiar with quantum physics. Some of us have studied this stuff in depth and for a long time, and know that there’s a much wider context to be considered than a single, specific experimental setup.
-
Length contraction in a block universe must be an illusion
No - there is only one train, but many observers. The property of “length” is not intrinsic to the train - instead, it describes a relationship between the train and a specific observer.
-
Definition of Atheism
I agree, the difference is in fact huge. What I meant by my comment is that the definitions may sound similar on the surface, to those who don’t think about them more carefully.
-
Definition of Atheism
I think this would simply be because most people on the Internet aren’t themselves academics, and thus may not immediately grasp the difference between these - superficially similar-sounding - definitions.
-
Can you be a scientist and still believe in religion?
I’d like to throw in two more notions, if I may. Firstly, a “negative” belief in the absence or falsity of something is itself a belief, same as believing “in” something. And before anyone says it - no, I do not come from any kind of theistic angle. It’s a general notion. Secondly, the concept of epistemic responsibility seems pertinent to the discussion. Basically it means we have a moral responsibility to critically evaluate the beliefs we hold in terms of available data. Are these beliefs justifiable? This goes equally for positive and negative beliefs.
-
Length contraction in a block universe must be an illusion
It depends on the observer of course - there will exist an observer in whose frame it is 1m, and there will also exist an observer in whose frame it is 100m. All of these observers are right - but only in their own frames. The length of the train is thus not an intrinsic property of it, any more than eg. its speed or kinetic energy. It is meaningful only in relation to a specific observer measuring it, so asking about its “real” length is meaningless. There are indeed quantities that all observers in spacetime agree on (tensors and invariants), but length is not one of them; it’s strictly a quantity that describes a relationship to a given observer only.
-
Can you be a scientist and still believe in religion?
Yes, and some religions do not have any concept of God, in the theistic sense.
-
A rational explanation for the dual slit experiment
Of course. The problem here though is that a duality is not a contradiction. You are making a category mistake. For example, consider the below picture, which is a rectangle-circle duality; there’s no contradiction, because the object in question is neither a rectangle nor a circle, yet contains aspects of both. Likewise with wave-particle duality - quantum objects (any type, not just electrons) sometimes exhibit particle-like behaviour, and sometimes wave-like behaviour, depending on how you look at them - while at the same time ‘being’ neither of those things. They are a separate ontological category to classical waves and particles. Which information is accessible depends on the observer.
-
Requirement for two "nows" to grasp the idea of Simultaneity
This is not directly related to relativity of simultaneity, since in the twin experiment, the reason for differential ageing is that part of the travelling twin’s journey isn’t inertial, so the symmetry between frames breaks down. That’s a different mechanism. You can see differential ageing in particle accelerators when using ion beams - fast beams spread slower (Coulomb forces) than slow beams, in the lab frame. A second ago on the distant observer’s clock; at t=0 at the place of the event; maybe a year in the future for yet another observer. That’s precisely the point - there is no universal time frame. It depends on the observer, and their relationships. Remember this is about simultaneity. And this is all correctly accounted for in the math, as pointed out.
-
Can you be a scientist and still believe in religion?
May I just throw in here that religion does not necessarily equal theism. Not everyone who identifies with a religion believes in a creator deity.
-
Delayed choice experiment (split from Question: Does the Double Slit Experiment prove Free Will?)
An ‘observer’ in quantum physics is any means by which some of the available information may be accessed. In this case, it is simply a screen at a certain location. The point is, an ‘observer’ does not need to be sentient or conscious. However, different types of observers may provide access to different information, so they do have a role to play in that sense. This isn’t a causal relationship though.