learn about the biggest current challenge (IMO) in physics ! we'll learn what it is and why it matters, and you'll get some helpful context to better understand this wild challenge!
I just stumbled upon her channel moments ago and my first observation was her hair 😂. Love her personality too though honestly she is awesome for the community and physics information consumption 😁
I have to comment on the current state of this subject as it's just too much fun atm. The reason we see friction between gravity and the standard model is, the laws of gravity, described by Einstein's general relativity theory, are geometrical. Whereas, the standard model is governed by quantum mechanics, whose mathematical rules seem to clash with the smooth nature of spacetime geometry predicted by Einstein. However, it turns out this might not actually be the case. What's so exciting about theoretical physics at the moment is, we're getting a lot of clues, provided by recent research, that suggests gravity and quantum mechanical laws could actually be intimately connected to each other in geometric ways that we did not expect at all. In other words, right now is one of the best times for anyone to study physics!
@JenFoxBot I have a new model about this. I wonder if you are friends with Kevin Ross of LEGO First robotics? We worked on the OS/2 kernel together, back in the day.
I clearly know nothing about the topic of gravity, I tought that it was "explained" by the mass (Higg's Boson) distorting space-time, so gravity would be only the shape the space-time around a mass. Thanks for the video and the oportunity to talk more about it!
ohh that's actually a great Q for follow-up! Higgs boson doesn't deal w/ gravity at all -- that discovery confirmed hypotheses in the Standard Model. (specifically, that the electromagnetic force and the weak nuclear force are the same force.)
@@JenFoxBot everything is the same "force". Physicist just play stupid games forever. Large hard on coll (the name that is not allowed in yt comms, because it is not a machine they claim to be). Tech is do nasty it has made my life pure hell.
@ernestschoenmakers8181 Oh, you _can_ quantize gravity, but you _can't_ renormalize it. The math trick you use for quantizing the electromagnetic field in QED doesn't work for quantizing the gravitational field. As an aside, currently there are, like, a hundred theories for "quantum gravity". None of which we've been capable of experimentally testing yet.
The Higgs mechanism gives certain particles *_inertial_* mass. There are two different kinds of things called "mass" in Newtonian Mechanics, which were assumed to be equivalent (long story). Einstein figured out how to prove that: yes, gravitational mass and inertial mass _are_ equivalent. The _exact_ mechanism however is needs a "quantum theory of gravity", which nobody knows for certain yet. Inertia comes from confinement (mostly at the quantum scale). The stress-energy tensor also only counts confined energy for contributing to gravity. (i.e. linear momentum and kinetic energy don't count.) (long story) (I started writing an explanation of isoweak interactions with left-handed leptons, but it was going to be long and technical, so ask me if you really want to hear it.)
However difficult you think gravity/standard model is complicated, I raise you turbulence as being the hardest thing to understand. Add onto that friction.
I'd argue there's a difference between complexity and mystery. just because something is complex doesn't mean we can't generally understand it - it's like the difference between "known unknowns" and "unknown unknowns". Turbulence is in the category of "known unknowns" whereas the discrepancy w/ general/special relativity and standard model fall into the "unknown unknowns".
So Jenna Levin's theory means that gravity is the macro manifestation of stuff happening on the micro , or on the quantum level , maybe fundamentally having the so called " spooky action at a distance " as the key to the riddle ? Is this what you mean ?
2 minutes in ~ ok, we agree. The conflict / contradiction between Einstein's General Relativity and Quantum Mechanics. Honourable mention goes to the Hubble Tension. My personal suggestion there, who says the rate of expansion, the rate of change of expansion, is the same everywhere and every-when? We have inflation ~ then a plateau, then the expansion seems to have started to speed up. Now we can't agree on what the rate is. What on Earth (figure of speech) makes you think the expansion is a constant? So you've got a 7% or 10% or something variation, depending on how you measure it. Call me Occam's razor but what makes you think the expansion or the acceleration in expansion, is the same at all times and all places? [Roll Eyes] Yes, a homogeneous universe is a good starting point, unless you have evidence it isn't. Well what do you call this? It has feathers and it waddles and it floats. And it has been known to quack. I suspect it's a duck...
interesting thoughts! i love the dark energy mystery and am excited to see that we're just beginning to scratch the surface. lots of opportunity to make radical discoveries here, would be super interested to see if, to your pt, the acceleration of expansion is different in different locations of the universe.
Relativity and standard model are just parts of a bigger picture - I suspect all models, even string theory which remains observationally unproven, have some elements that are correct and we dont know which parts or how it all comes together. I suspect the key is related to Susskind/Maldacena ER=EPR.
No, the quantum gravity connection is exoteric. We progress well without konwing it, we don't even know whether it will be a problem in the end. Instead, the most fundamental problem is that we don't know the reality (ontology) underlying quantum mechanics. Nature deals with it every day the whole day and we have no clue. We remain baffled by quantum entanglement and can not understand it.
Is the relationship between gravitational attraction and mass absolutely linear? Can we rule out synergy -- force increasing once a "critical mass" is reached?
good question! In Newton's equations, the relationship between the gravitational force and *one* mass is linear: F = (G*m1*m2)/r^2 -- so if you increase the mass of one object, the gravitational force exerted b/w the two objects increases linearly. However, Newton's theory is a simplified version of gravity and doesn't always apply (e.g. extreme cases like black holes). Einstein's General Relativity Field Equations are more complicated, which means that gravity does not increase linearly w/ mass forever: en.wikipedia.org/wiki/General_relativity#Einstein's%20equations
I'm an amateur theoretical physicist, and I'm about to publish a book on kdb titled 'The Reasoned Reality'. The book touched on concepts like: Reasoning, components of Reality, Numbers, The universe, Nothingness, The Grand unified theory, p vs np, and the general mathematical truths underlying reality. You should definitely check it out.
The whole way through, I couldn't stop wondering about dark matter. MOND doesn't work out, but something is holding together galaxies (and more). The hope has been that dark matter would show up in particle physics. So, it has to be a related problem.... somehow. Maybe you could do that video.
How much would I weigh if I stood at or near the center or the Earth? All of the mass would be above me! At what point would the mass above cancel out the mass below? Q2: How many charm quarks do you have to ingest to become so quarky?
A1: You would feel weightless at the Earth's center of mass... because you have the exact same amount of mass symmetricly in all directions around you. It's Newton's "Shell Theorem".
Huh, the biggest question isn't a great way to phrase it, but surely makes it a lot harder to answer. If you only go by personal opinion it gets a lot easier to answer, and maybe I should take that route too... But I'll instead watch your answer, think about what I'd answer immediately and meditate on this a couple of months about, and, if I'm still alive, maybe I'll have a great answer to it. My gut feeling is "why unification of gravity and quantum mechanics failed so far, as in, we have not made much in detection about it?". I'll see what you say. I think this is too much of a vibe answer on my part though. Oh, you are kinda of the same mind as vibe goes. Yes, if answering this more quickly I'd give an answer in much the same nature as this vid. I thought about this style of question many times and lately I've been inclined to lean a lot more on "maybe we should assume relativity is wrong" or "time is the problem" than "let's make quantum mechanics agree in large scales".
I also agree that it seems more likely that it's gravity that has to give something up. There are many reasons we would think this: - we know gravity less, experimentally, because it's a long range force and a very weak force compared to the others, so it demands big scales; - we use a hierarchy of distances to calculate stuff on the big scales, which makes the errors compound and basically makes cosmological experiments a error prone nightmare; - we have a lot easier access to measuring smaller scales, even when they are difficult to probe, in which case we usually just say "more better" and it usually just works most of the time; - we understand smaller scales to bigger precision because it's more useful to us in our scales, even when experiments are expensive they tend to just be repeatable; - we have a very hard time making and maintaining anything probing bigger scales, and usually those experiments tend to be more difficult to plan and more expensive, while also being harder to repeat and harder to steer to other uses. One could claim this is a bias towards what we can observe, but... This is a more productive approach than trying to say the theoretical reasoning is sound. We don't know what anything is until we measure it. That's just the reality of it. The "soundness" of a mathematical hypothesis is very hard, at times, to quantify, and, unless it's the "we never detected anything that disobeys this" it's also not an attitude we coherently always employ (e.g. magnetic monopoles never being detected and the scientific community is ok with it, for many technical reasons, but in fact justifying our ignorance and not trying to nail this down relentlessly).
@@VeteranVandal love this, your pts re: why gravity are super compelling and, well, on point! Agree 💯 also appreciate your thoughtful consideration and contemplation! Love these kinds of comments bc I get to learn from others and it helps me think of things in new ways. thank you for sharing!
@@JenFoxBot and the contemplation isn't done, unfortunately. From what I could see lately in some articles we could perhaps also argue about dark matter and other cosmological phenomena as a possible answer, but I'm not sure if the question is "greater" or "bigger" than unification is, unless of course we find out unification is inevitably impossible, which is a big, chunky claim that'll require big, chunky evidence, hilariously enough. I do find some compelling reasons to say the last classical physics problems are also big questions... But justifying all of this requires too much more bits of information in this (likely unworthy) format of commenting. The most unfortunate thing about all of this is that such a question will never have a definite answer, which will keep bothering me forever. I guess ignorance is bliss, knowledge is power and power has consequences always after exerted...
Planets dont sink towards the sun, for now; When they lose inertia (tangential velocity), they will sink towards the sun, but then a new phenomenon will appear, at particular parameter values, they will aquire a new tangential velocity, this prevents central collisions, another way to say it is: gravity force is no a central force. Of course this contadicts the mathematical form of gravity force as is known today.
great question! it's hypothesized that it is discrete, i.e., yes, that it has a "mesh" size that you would see if you could zoom in that far. it's likely smaller than the plank length, and would require energies on the order of the big bang sooooooo.... it's very difficult to observe, to say the least!
ohh love this question! I bet Janna Levin's books would be a good place to start: jannalevin.com/books/black-hole-survival-guide/ I also enjoy Neil DeGrasse Tyson's podcast, "StarTalk"! Looks like he has a course here: www.thegreatcourses.com/courses/the-inexplicable-universe-unsolved-mysteries
Our model of gravity is wrong! The speed of light is not a constant as once thought, and this has now been proved by Electrodynamic theory and by Experiments done by many independent researchers. The results clearly show that light propagates instantaneously when it is created by a source, and reduces to approximately the speed of light in the farfield, about one wavelength from the source, and never becomes equal to exactly c. This corresponds the phase speed, group speed, and information speed. Any theory assuming the speed of light is a constant, such as Special Relativity and General Relativity are wrong, and it has implications to Quantum theories as well. So this fact about the speed of light affects all of Modern Physics. Often it is stated that Relativity has been verified by so many experiments, how can it be wrong. Well no experiment can prove a theory, and can only provide evidence that a theory is correct. But one experiment can absolutely disprove a theory, and the new speed of light experiments proving the speed of light is not a constant is such a proof. So what does it mean? Well a derivation of Relativity using instantaneous nearfield light yields Galilean Relativity. This can easily seen by inserting c=infinity into the Lorentz Transform, yielding the GalileanTransform, where time is the same in all inertial frames. So a moving object observed with instantaneous nearfield light will yield no Relativistic effects, whereas by changing the frequency of the light such that farfield light is used will observe Relativistic effects. But since time and space are real and independent of the frequency of light used to measure its effects, then one must conclude the effects of Relativity are just an optical illusion. Since General Relativity is based on Special Relativity, then it has the same problem. A better theory of Gravity is Gravitoelectromagnetism which assumes gravity can be mathematically described by 4 Maxwell equations, similar to to those of electromagnetic theory. It is well known that General Relativity reduces to Gravitoelectromagnetism for weak fields, which is all that we observe. Using this theory, analysis of an oscillating mass yields a wave equation set equal to a source term. Analysis of this equation shows that the phase speed, group speed, and information speed are instantaneous in the nearfield and reduce to the speed of light in the farfield. This theory then accounts for all the observed gravitational effects including instantaneous nearfield and the speed of light farfield. The main difference is that this theory is a field theory, and not a geometrical theory like General Relativity. Because it is a field theory, Gravity can be then be quantized as the Graviton. Lastly it should be mentioned that this research shows that the Pilot Wave interpretation of Quantum Mechanics can no longer be criticized for requiring instantaneous interaction of the pilot wave, thereby violating Relativity. It should also be noted that nearfield electromagnetic fields can be explained by quantum mechanics using the Pilot Wave interpretation of quantum mechanics and the Heisenberg uncertainty principle (HUP), where Δx and Δp are interpreted as averages, and not the uncertainty in the values as in other interpretations of quantum mechanics. So in HUP: Δx Δp = h, where Δp=mΔv, and m is an effective mass due to momentum, thus HUP becomes: Δx Δv = h/m. In the nearfield where the field is created, Δx=0, therefore Δv=infinity. In the farfield, HUP: Δx Δp = h, where p = h/λ. HUP then becomes: Δx h/λ = h, or Δx=λ. Also in the farfield HUP becomes: λmΔv=h, thus Δv=h/(mλ). Since p=h/λ, then Δv=p/m. Also since p=mc, then Δv=c. So in summary, in the nearfield Δv=infinity, and in the farfield Δv=c, where Δv is the average velocity of the photon according to Pilot Wave theory. Consequently the Pilot wave interpretation should become the preferred interpretation of Quantum Mechanics. It should also be noted that this argument can be applied to all fields, including the graviton. Hence all fields should exhibit instantaneous nearfield and speed c farfield behavior, and this can explain the non-local effects observed in quantum entangled particles. *RU-vid presentation of above arguments: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-sePdJ7vSQvQ.html *More extensive paper for the above arguments: William D. Walker and Dag Stranneby, A New Interpretation of Relativity, 2023: vixra.org/abs/2309.0145 *Electromagnetic pulse experiment paper: www.techrxiv.org/doi/full/10.36227/techrxiv.170862178.82175798/v1 Dr. William Walker - PhD in physics from ETH Zurich, 1997
Jen, you have another 4 digits. We want to see more characters. Like: Science squirrel, Plutonium Panda and the best Math Mouse! 😀 Hello from Australia !
MATH MOUSE!!! i love that. yes! i do have more finger puppets (you actually got one of them right!) but so far i've only come up with physics + tech questions so only physics penguin and techie tiger have made an appearance. that said, if you have a question that touches on other STEM subjects, the other puppet friends would pop in🙃
Well... what we measure as "time" emerges from some other lower-level process (along with what we call "space"). The issue with General Relativity is that it gives you the geometry of spacetime.... I mean, your background _coordinate system_ [x,y,z,t] Quantum Mechanics is a Lagrangian that takes place in a [x,y,z,t] coordinate system, that's just there in the background. QM doesn't change or interact with the coordinate system in any way. A quantum theory of gravity needs to explain how the [x,y,z,t] coordinates themselves change when, and where, there's a bunch of stuff in it. (I'm trying to keep this explanation simple. ) (Yeah, you can use [r,θ,φ,t] or whatever your favorite coordinate system is. I just used Cartesian coordinates aa an example because everyone knows them.)
Why should they fit together, in the sense of a unified theory? Perhaps nature is simply not built on a single principle? At least so far, unification seems to me to be more of a wish than a reality. When we build houses, we don't build them from a single crystal. So why should everything in the universe come from a single crystal (or whatever you feel was first)?
great question! nature certainly doesn't have to conform to our expectations, and quantum physics is a perfect example of that. the issue w/ standard model vs. general relativity is that there's currently no way to accommodate the SM forces w/in GR and vice versa, which means that something is missing, or wrong, with one (or both) theories. it's kind of like kicking a soccer ball: you learn how to aim a soccer ball to score a goal, and you modify your force depending on how far you are from the goal. if soccer were like SM and GR, it would be like the soccer ball went the opposite direction you expected it to. again, it's not about trying to force nature into a specific theory, it's about understanding where our predictions are accurate and where they have gaps/errors. to your point, the gaps don't mean that the SM and GR forces are the same, just that we're missing something big. lots of explanations/experiments have been tried and we've been slowly ruling the more obvious things out.
how often happens that you explain some physics and someone from audiance asks completely irrelevant question? (suggesting not get a single thing you are talking about)
If all particles possess MOBILITY (magnitude and direction of motion) inbuilt in them instead of MASS, then all 4 forces become superfluous, as then they can all be derived as functions of this single property of all matter. Rest can only occur as resultant balancing of the mobilities of all interacting particles concerned. Not only forces, but practically all properties of matter (energy, mass, charge, temperature, etc.....) would be derivable as functions of this single property. And current atom model would prove totally irrelevant.
“Biggest”??? Isn’t it “a bit” too presumptuous, even before watching the clip to its end. We, physicists, tend not to use superlatives. Usually… But, since you brought up the word, the biggest problem in science today is, that research depends on grants and therefore politicized and focuses on low risk topics. As Sabine pointed out once. Dr. Hossenfelder, I mean.
@@sebastianfeuerstein9306 In a free Capitalist world you are valued by your merit and free to express your thoughts, whatever they are (as long as the society is not infected by the Neo-Nazi Woke virus, of course). Try to live in Russia, China, North Korea, Cuba or any other "non Capitalist" society for a while and you'll change your tune pretty quickly (if you would be allowed to).... The problem is that in free Capitalist society we have a complete freedom of information flow and let even idiots with no critical objective thinking mechanism form their opinions about things they don't know. This, contrary to complete control and censorship of information and aggressive disinformation that takes place in societies, you never lived in. How do I know? Ask Yeonme Park.
@@sebastianfeuerstein9306 Do you still live in Germany? If you don't like it there, move to a "non-capitalist" North Korea or Cuba. I am not blaming you for being an ignoramus. I am blaming my generation for not protecting the Western Free Society from the Russian / Chinese disinformation cancer.
What is it all about? It was not a good play written by physicists so far! We should have formalized it again; it probably would have ended in tragedy, lovely human:) “Ah Love! could thou and I with Fate conspire To grasp this sorry Scheme of Things entire, Would not we shatter it to bits -- and then Re-mould it nearer to the Heart's Desire!”
I think that the biggest problem is that we really know very little about what things really are. We know just about everything that can be measured about electrical and magnetic fields yet we do not know what it is. We say that it has to do with the electron and what we can measure around it but that is only how it shows up to us and not what it really is. In my opinion an electron is a manifestation of energy but I do not know what energy is. The simplest form of energy that I know of is an EM wave (electric current, radio signal, radiated heat, light etc.) and that we only know about how it behaves and not what it is. It is my opinion that all matter is a kind of standing waves of energy that for some reason is kept mostly localised (doesn't propagate in all directions like EM waves). I have seen a number of ideas that explains some of it but none that totally satisfy me. Pavel Werner's "Ring Theory" is an example.
Gravity cannot be quantized because gravity is not a force, and there is no such thing as a singularity. Nobody has physically demonstrated singularities to exist. There is no reason to believe that singularities exist, not even in black holes, because curvature of space is caused by the non-zero presence of matter. Gravity is merely and ONLY curvature of space; gravity is not a force but merely redirection or reflection of kinetic energy. NOTHING is inside a black hole, not even existence of space or spatial dimensions; all of its matter that cause curvature of space is contained in its event horizon surface. Time stops at the event horizon surface, so nothing can "fall" inside the black hole. There is no loss of information, because all of the matter that causes curvature of space is contained in the event horizon surface. The event horizon surface of the black hole is an "edge" of the universe reality. Gravity is merely the curvature of space as it is "pushed out of the way" by matter. Gravity is not a force, but only the reflection or redirection of kinetic energy that is already in the matter. That's why objects of unequal mass will accelerate at the same rate under the influence of gravity. If gravity was a force that was imparting its energy into objects, then the objects of differing mass would not accelerate at the same rate. For objects of differing masses to fall at the same acceleration rate, they must be invested with differing kinetic energy relative to their masses by lifting the objects. Where did the original "lift" of kinetic energy come from? Cosmic inflation (also known as the "Big Bang") provided the original "lift" to invest the kinetic energy that is now in all matter in the universe. The question is whether cosmic inflation, which happened faster than the speed of light, was sufficient for the "escape velocity" to prevent future gravitational collapse of the universe? It seems to me that cosmic inflation was not an inertial frame of reference, so "escape velocity" has not happened, because it only applies to inertial frames of reference. The universe will ultimately collapse, causing an unending series of births and deaths. The universe is finite, unbounded, and eternal.
*ChatGPT4o:* Your perspective presents a unique and thought-provoking interpretation of gravity, black holes, and the nature of the universe. Let's explore and dissect some key points to clarify these concepts. *Gravity and Curvature of Space* 1. *Gravity as Curvature:* - According to General Relativity, gravity is indeed the curvature of spacetime caused by the presence of mass and energy. This curvature affects the paths of objects, making them appear to experience a "force" of attraction. 2. *Gravity Not a Force:* - In the context of General Relativity, gravity is not a force in the traditional Newtonian sense but a manifestation of curved spacetime. Objects follow geodesics, the straightest possible paths in curved spacetime, which we perceive as gravitational attraction. *Black Holes and Singularities* 1. *Singularities:* - Singularities are theoretical points where densities become infinite, and our current physical theories break down. While singularities haven't been observed directly, they are predicted by solutions to Einstein's equations under certain conditions (e.g., the center of black holes). 2. *Event Horizon:* - The event horizon of a black hole is a boundary beyond which nothing, not even light, can escape. The idea that time stops at the event horizon is an oversimplification; time dilation becomes extreme, but from the infalling object's perspective, it crosses the event horizon in finite time. 3. *Inside Black Holes:* - The statement that nothing exists inside a black hole, including space, is contentious. Current theories suggest that beyond the event horizon, spacetime continues to exist, but our understanding is incomplete due to singularity. *Information and Black Holes* 1. *Information Paradox:* - The black hole information paradox concerns whether information that falls into a black hole is lost or somehow preserved. Current research suggests that information might be encoded on the event horizon (Hawking radiation and holographic principles). *Kinetic Energy and Mass* 1. *Acceleration in Gravity:* - In a gravitational field, objects of different masses accelerate at the same rate due to the equivalence principle, which states that gravitational mass (source of gravitational force) and inertial mass (resistance to acceleration) are equivalent. This is why all objects experience the same acceleration in free fall, regardless of their mass. *Cosmic Inflation and Universe Expansion* 1. *Cosmic Inflation:* - Cosmic inflation is a rapid expansion of the universe that occurred fractions of a second after the Big Bang. It explains the large-scale uniformity and structure of the universe. 2. *Escape Velocity and Expansion:* - The expansion of the universe is described by cosmological models like the FLRW metric, which don't directly apply Newtonian concepts like escape velocity. Instead, the universe's expansion rate is governed by the dynamics of spacetime itself, influenced by dark energy and the overall energy content. *Fate of the Universe* 1. *Ultimate Fate:* - The fate of the universe depends on various factors, including dark energy, dark matter, and the overall curvature of the universe. Current observations suggest an accelerating expansion, implying the universe might continue expanding indefinitely. *Summary* Your interpretation intertwines multiple concepts from General Relativity and cosmology with personal insights. While some points align with established scientific theories, others diverge or simplify complex phenomena. Continuous advancements in theoretical physics and observational astronomy will help refine our understanding of these profound aspects of the universe.
Gravitation is a manifestation of space time curvature It cannot be unified with electromagnetic, weak, and strong interactions; however, they all can interact Gravitation pushes; it does not pull Quantum gravitation is same as gravitation but at the quantum level
Mr. Spock of the Organization of Physics Undergraduate Students says we should blast your wiggly buns off for mocking him. Could you dive into the Gauge Theory Gravity of Lasenby, Doran and Gull and Cohl Furey's videos on division algebras and Physics? Also, could you explain what a double copy is? Octonions, Standard Model and Unification 2023 27/10/23 Speaker: Anthony Lasenby Title: Geometric Algebra, Octonions and the Standard Model School: Kavli Institute for Cosmology and Cavendish Laboratory, Cambridge ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-0m__fhtkMzg.html
I wish you'd taken a prediction, a formula, something from the theory of gravity and brought it over to the standard model so we could see it not working with our own eyes. And/or vice versa.
I have a solution to the biggest problem in physics. If you consider the nature of quarks and the nature of large celestial objects...oops, never mind.
well this is a rude comment. i like my singing and silliness, and i like who i am. if you don't, there are lots of other channels to go watch without wasting your time trying to make others feel bad.
Classical physics still considers 0D subatomic, indivisible stuff like quarks "not fundamental" and 1D, 2D, 3D atomic, divisible stuff like protons and neutrons "fundamental". Classical physics is incoherent from first-principles. Calling divisible stuff "fundamental" is incredibly silly. Also, if 0 = 0 + 0i then 0D = 0D + 0Di.
Ignorance, arrogance, no balls, just obey masters and produce nonsense. They know true rules, but you can hide everything with indoctrination. Because elirereptilrdshtpsychos are in progress to wipe us out
