Quotes from Lisa Randall

My second concern about Occam's Razor is just a matter of fact. The world is more complicated than any of us would have been likely to conceive. Some particles and properties don't seem necessary to any physical processes that matter—at least according to what we've deduced so far. Yet they exist. Sometimes the simplest model just isn't the correct one.

The uncertainty principle tells us that you need high-momentum particles to probe or influence physical processes at short distances, and special relativity relates that momentum to a mass.

Gravity in our world would be weak because extra dimensions are large, not because there is fundamentally a big mass responsible for the tiny gravitational force.

the young Sun's energy output was probably about 70 percent of what it is today. With the Sun's initially lower luminosity, even the water that did form wouldn't have been in a liquid phase without some other explanation—a quandary known as "The Faint Sun Paradox.

The fermionic nature of most fundamental particles determines many properties of the matter around us. The Pauli exclusion principle, in particular, states that two fermions of the same type will never be found in the same place. The exclusion principle is what gives the atom the structure upon which chemistry is based.

the continuously habitable zone, which is the region that could have supported liquid water over the lifetime of the planet. According to current climate models, the continuous habitable zone is a more restricted region within fifteen percent of the Earth-Sun distance.

calculations

In fact, essentially most of the great movie disaster scenarios (with the exception of a zombie apocalypse) follow in the wake of a sufficiently big impact.

we currently live in a region—300 light-years across—called the Local Bubble, which is a vacuum-like domain with very low hydrogen density within the interstellar medium in the Orion Arm of the Milky Way.

When a field takes a nonzero value, the best way to think about it is to imagine space manifesting the charge that the field carries, but not containing any actual particles.

When it comes to the world around us, is there any choice but to explore?

Perhaps a quarter of meteoroid impacts have led to potentially profitable deposits—at least half of which have already been exploited.

Nothing about our world is inconsistent with the existence of a multiverse.

Solar-sized star formation requires extremely cool temperatures—tens of kelvins. Overly high temperature gas never gets sufficiently concentrated to ignite nuclear burning.

The uncertainty principle of quantum mechanics, coupled with the relations of special relativity, tell us that, using physical constants, we can relate a particle's mass, energy, and momentum to the minimum size of the region in which a particle of that energy can experience forces or interactions.

if there is a conventional explanation for an observation, it is almost always the right one. Radical departures should be accepted only when they explain phenomena that older ideas fail to accommodate. In

The weak force violates parity symmetry by acting differently on left-handed and right-handed particles. It turns out that only left-handed particles experience the weak force. For example, a left-handed electron would experience the weak force, whereas one spinning to the right would not. Experiments show this clearly—it's the way the world works—but there is no intuitive, mechanical explanation for why this should be so.

The supercontinent Pangaea split in the Mesozoic era into the continents we see today, and resulted in extensive land movement over time.

COBE discovered the quantum fluctuations that were generated when the Universe was roughly the size of a grain of sand, and which are ultimately the origin of you

Trillions of solar neutrinos pass through you each second, but interact so weakly that you never notice.

But the Universe is by definition a single entity and in principle its components interact. This book explores

So, in a sense, looking under the lamppost for dark matter is appropriate.

The problem is that string theory is defined at an energy scale that is about ten million billion times larger than those we can experimentally explore with our current instruments.

Maxwell was a brilliant scientist who counted among his many interests optics and color, the mathematics of ovals, thermodynamics, the rings of Saturn, measuring latitude with a bowl of treacle, and the question of how cats land upright while conserving angular momentum when dropped upside down.