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If my computer asks me a question and I know for sure that it was not programmed to ask that question, then I will suspect that the computer has spontaneously generated that question. I will then suspect the computer has developed a sense of curiosity, which might go hand-in-hand with conciousness. Or suppose the computer simply accesses the internet by itself, without being prompted to, and then announces “hey, I just discovered this article on…” that would perhaps imply conciousness. In fact, it would also imply that the computer has developed a “theory of mind” because it thinks I will be interested to hear what it has just learned.
The gravitational waves are generated from a point in space just outside the combined event horizon when the two black holes emerge, hence the waves can escape. Nothing that is generated within the combined event horizon can escape. Given that all the mass of each black hole is concentrated at its centre, the event horizon is not an actual physical surface – it is simply a region in space. Hence, when the two event horizons of the colliding black holes merge into one, the central masses of each black hole must still be moving towards each other. Do they continue to spiral inwards towards a final merger? Presumably so, but we will never detect gravitational waves from that part of the collision.
In my view, the point to note is that the numerator of the equation is increasing AND the denominator is decreasing, hence the density increases A LOT with increasing velocity.
From the point of view of someone travelling on the block, nothing seems to change, i.e. the mass, volume and density are the same as at rest. One explanation is that this person considers the Universe to be speeding by why he and his block remain stationary. Another explanation is that he is subject to the same Lorenz contraction etc, so any measuring devices he carrys with him will show no change. It is in the math, but in practice it seems like a moot point because I cannot NOW see what is happening “now” in a distant galaxy. If a supenova happens in a distant galaxy at what I would consider to be the same moment in which I am typing this, I will not know about it and no-one on Earth will now about it until millions of years later. When the future eartlings see the supernova, they will think of it as happening in their “now” even though they know it happened millions of years in their past. I often think we are confusing two different concepts when we think about time – I wonder if time as a dimension (in which the time slices would be cut) is different from the concept of past, present, and future, the latter being a product of our perception (as with wavelengths of light being pereived as different colours). Maybe we need to disentangle these two concepts of time.
“If the particles initially didn’t had mass(before higgs field gave them mass) , how did they existed physically?
What’s the physical interpretation about existence of these particles even?”Mass is not really the amount of matter in an object, although it is often described to us that way in physics classes. Mass is a characteristic that enables particles to interact gravitationally. It is not essential for a particle to have mass, any more than it is essential for a particle to have electrical charge.
Nevertheless, the question of what is the physical interpretation of existance is an interesting one – it may even be the most fundamental question. What is left when we strip away the gravitational, electromagentic, strong and weak nuclear interactions? What are the objects themesleves, the things that are interacting? I have a lens that gives a higly-magnified image when I hold it close to the object I am viewing. As I slowly move the lens away from the object, the image gradually becomes blurred and is eventually lost altogether. However, as I continue to move the lens slowly away from the object, the image becomes sharp again, but upside down. This reminds me of the aspects of string theory described in an ealier video. This makes me think that looking at the universe with string theory is like looking at fundamental truth through such a lens rather than looking at the fundamental truth directly. So when we use string theory we are never really seeing that fundamental truth – we are always seeing an image that preserves some properties of the reality but is in some ways distorted. So, to see the fundamental truth, we have to put down the lens. This might not be easy – all of our theories might be metaphorical lenses through which we see various distortions of reality. Moreover, it might not be possible to put down the lens. We cannot look at the universe from “outside”, as there is no outside. And the fabric of the universe itself might be creating these distortions (e.g. perhaps the distortions would vanish if all matter was removed from the universe). To change the metaphor only slightly, it is as if we are living inside a hall of mirrors, and the distorting mirrors are an integral part of the very structure of our universe. So, there is such a thing as fundamental reality, but how can we ever hope to see it?
This is not a theory, it is a kind of philosophy. There are some interesting thoughts and ideas in there, but what bearing does it have on reality? It is just a mathematical construct – not even that, it is a groping towards a mathematical construct. The speaker sometimes says string theory hasn’t actually been formulated yet – all the thought has gone into what string theorists want string theory to do. It is a geometrical theory, so it is all about perspectives – things look different from different perspectives. So, just because things look different from one frame of reference to another, does that mean nothing is fundamental? Might it not be that all points of view of equally fundamental?