But is the multiverse science

Despite the growing popularity of the multiverse proposal, it must be admitted that many physicists remain deeply uncomfortable with it. The reason is clear the idea is highly speculative and, from both a cosmological and a particle physics perspective, the reality of a multiverse is currently untestable. Indeed, it may always remain so, in the sense that astronomers may never be able to observe the other universes with telescopes a and particle physicists may never be able to observe the extra...

The pros and cons of parallel universes

So should you believe in parallel universes The principal arguments against them are that they are wasteful and that they are weird. The wastefulness argument is that multiverse theories are vulnerable to Occam's razor because they postulate the existence of other worlds that we can never observe. Yet this argument can be turned around. For what precisely would nature be wasting Certainly not space, mass or atoms - the uncontroversial Level I multiverse already contains an infinite amount of...

Microanthropic principle the entropic ansatz

A hint toward a more plausible (though not so easily applicable) alternative is discernible in the response to the eschatological problem posed by Islam 28 that was provided by Dyson, who suggested 29 that what really matters is not the proper time duration of an interval, but how much information is effectively processed therein. There is, of course, room for discussion about how to quantify what is effectively processed (as opposed to what is merely stored in a memory), even in the case of an...

Cosmology and the many worlds interpretation of quantum mechanics

Sektion Physik, Ludwig-Maximilians-Universitat Although the mathematical structure of quantum mechanics was understood within a few years after it was invented, numerous quantum paradoxes still disturb 'simple-minded' physicists. Most of them, as 'naive realists', would probably never take Bohr's own over-philosophical and over-complicated treatment of these paradoxes seriously if they realized the philosophical consequences of the Copenhagen interpretation. To make my meaning clearer, let me...

What are Level IV parallel universes like

We can test and potentially rule out any theory by computing probability distributions for our future perceptions - given our past perceptions - and comparing the predictions with the observed outcome. In a multiverse theory, there is typically more than one SAS that has experienced a past life identical to yours, so there is no way to determine which one is you. To make predictions, you therefore have to compute what fractions of them will perceive what in the future. This leads to the...

Status of the anthropic coincidences

My focus here will be entirely on the strong anthropic arguments, since I have always regarded the weak ones as relatively uncontroversial. The first set of fine-tunings involved the four dimensionless coupling constants. These were taken to be a 102 for electromagnetism, aG 104 for gravity, aW 1010 for the weak force and aS 10 for the strong force. The second set of fine-tunings was associated with the formation of galaxies and their subsequent fragmentation into stars. These involved various...

The cosmic uroborus

Taken together, scientific progress on both the outer and inner fronts can certainly be regarded as a triumph. In particular, physics has revealed a unity about the Universe which makes it clear that everything is connected in a way which would have seemed inconceivable a few decades ago. This unity is succinctly encapsulated in the image of the uroborus i.e. the snake eating its own tail . This is shown in Fig. 1.2 adapted from a picture originally presented by Sheldon Glashow and demonstrates...