Tag Info

New answers tagged

0

If there is evidence of some balance problem that involves energy the missing energy must be somewhere and the extra energy must come from somwhere. A good way to see this was detailed in the Fyenman Lectures, where Richard Feyman explained conservation of energy in a very simple way. So the answer is: No, Energy cannot be Created or Destroyed.


6

Assuming you take the usual position that dark matter interacts only via the weak and gravitational forces, then it doesn't just interact weakly with baryonic matter but it also interacts weakly with other dark matter. That makes it extremely unlikely that dark matter will form the sort of complex structures that make up you and I. I'm afraid it seems very ...


1

There are a couple of related questions: What elements can be created in the fusion process of different types of stars? What is the heaviest element possible produced in a supernova? though surprisingly I can't find an exact duplicate (which probably just means I didn't look hard enough). Iron is the most stable nucleus so in principle all other nuclei ...


1

Objects moving in an expanding universe experience an apparent drag force called the Hubble drag and given by: $$ D = 2\frac{\dot{a}}{a}\mathbf{u} $$ where $\mathbf{u}$ is the comoving velocity and $a$ is the scale factor. This isn't a real force, it's the result of the universe expanding away from the moving object, but the end result is that in an ...


2

Is it possible that universe is not expanding but instead being dragged into singularity? Yes. That possibility is called the Big Rip. 'dragged into a singularity' can happen even while 'expanding', so they are not contradictory. It would occur if the rate of cosmic acceleration is exponential. In the Big Rip scenario, there is a finite time in the future ...


1

The scientific paper linked in the article you read is saying that it seems that there's a clustering of mass beyond the reach of current all-sky galaxy redshift surveys that is pulling the local volume more to one side. Such clusterings are possible in the framework of the standard $\Lambda$CDM cosmology, but a clustering large enough to explain the data is ...


2

Is it possible that universe is not expanding but instead being dragged into singularity? No. We see galactic redshift every where we look, the galaxies are moving apart like the raisin-cake analogy. There is no overall gravitational field in the universe. You may have heard about "the big crunch" but I'm afraid it's popscience. The universe didn't contract ...


2

There are three types of matter/energy we consider when calculating how the universe expands: Matter - both normal matter and dark matter Radiation Dark energy We measure the expansion of the universe using a scale factor that we normally denote by $a$. The scale factor increases with time as the universe expands, and if we look backwards in time we see ...


0

The expansion of space is like stretching a rubber sheet. (Don't take this analogy too seriously. It works for this explanation but fails elsewhere.) The mass of the rubber sheet stays the same as it gets bigger. Space expands, but mass does not increase with it.


-1

I have modelled the vacuum as a set of identical, bi-modal, frequency-quantised quantum harmonic oscillators. Using some of the data from the Planck mission and taking the number of baryons in the universe as 10^80 yields the following: the diameter of the universe is 94.3 x10^9 L yrs ( which compares favourably with that value estimated by Gott et al); ...


-1

What do we mean by the size of the universe? Exactly that. We mean what we say. Isn't it true that the concept of length exists only within the universe? Since the universe is everything, yes. But that doesn't stop us talking about the size of the universe. Are we simply measuring the observable universe, that is to say, the spatial limits of our ...


0

It is difficult to say. When you say "The size of the Universe" some people think about the observable Universe, while others, like me, think about the entire Universe, beyond just what we can observe. When it comes to length in the entire Universe, it's useless. the Universe is infinite so no matter what measurement we create, it will be insufficient to ...


0

This means that the universe cannot be simulated by a Turing Machine, it's not related to being able to write down th equations of physics. If the laws of physics are non-computable, you then also lift the restrictions any computing device is subject to and expand that to whatever the non-computable laws of physics would allow. E.g. classical physics is ...


0

If everything expands at the same porpotion it require more enery to do everything beacasue the law of Conservation of Energy states that energy cannot be created or destroyed but be transformed from one form to another.


0

If you are a 2D ant confined to the 2D surface of a balloon, and someone is blowing up your balloon, you might notice that your world is expanding; objects are getting further away from each other! However, there would be no "center of expansion". No point on the balloon would any more be the center than any other; the space you are living on is just ...



Top 50 recent answers are included